# TeV Particle Astrophysics 2017 (TeVPA 2017)

US/Eastern
Columbus, Ohio, USA

#### Columbus, Ohio, USA

Hosted by the Center for Cosmology and AstroParticle Physics (CCAPP), The Ohio State University
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Description

Videos: The TeVPA 2017 YouTube channel has videos of the plenary talks and video advertisements of some parallel talks

TeVPA is a five-day conference aiming at providing the stage for the most recent advances in the booming field of Astroparticle Physics, bringing together leading members of the scientific communities that are contributing to its success.

TeVPA 2017 will be hosted by the Center for Cosmology and AstroParticle Physics (CCAPP) of The Ohio State University.

First, to express your interest in attending, please register as participant. This is a non-binding expression of interest to attend TeVPA. At registration, you can also indicate if you are interested in taking part of the optional pre-conference mini-workshops on Sunday, August 6.

Second, to express your interest in presenting a talk, please submit an abstract. This is a non-binding expression of interest to attend and present a talk at TeVPA. All contributions will be oral, and we have scheduled many parallel talks to give students and postdocs the chance to present their work. Your submitted abstract will be reviewed by us and we will inform you as soon as we have made a decision on it. If your abstract is accepted and you confirm your participation (see below), you will be required to register as a participant (see above) if you have not yet done so.

Third and last, to confirm your participation in TeVPA --- regardless of whether or not you submitted an abstract --- please pay the conference fee.  After that, you should make travel and accommodation arrangements.

Undergraduate students are welcomed.  We want you to have the opportunity to get to know a community which you might join in the future. Therefore, you are free to attend TeVPA without having to pay the conference fee. However, you are still required to register as participant. You are welcome to attend the conference reception. However, attending the conference dinner requires payment of the conference fee (student rate, $250). In the registration form, please say yes to attending the reception (if you wish to attend) and no to attending dinner. Important dates  4 April 2017 Registration and abstract submission open; discounted rate booking at the DoubleTree hotel starts 2 June 2017 30 June 2017 Extended deadline for abstract submission and early-bird registration 6 July 2017 Deadline for discounted rate booking at the DoubleTree hotel 24 July 2017 Final deadline for abstract submission and registration 6 August 2017 Pre-conference mini-workshops (optional) 7 August 2017 Conference starts 11 August 2017 Conference ends Plenary speakers  Nima Arkani-Hamed (IAS Princeton) Victoria Kaspi (McGill U.) Anna Barnacka (Harvard) Marek Kowalski (DESY) Julia Becker Tjus (Ruhr U. Bochum) Elisabeth Krause (Stanford / SLAC) Veronica Bindi (U. Hawaii at Manoa) Mariangela Lisanti (Princeton U.) Esra Bulbul (MIT) Raffaella Margutti (Northwestern U.) Francis-Yan Cyr-Racine (Harvard) Miguel Mostafá (Penn State U.) Emma de Oña Wilhelmi (CSIC-IEEC) Hitoshi Murayama (UC Berkeley) Ralph Engel (KIT) Samaya Nissanke (Radboud U.) Gianluca Gregori (U. of Oxford) Tracy Slatyer (MIT) Daniele Gaggero (GRAPPA) Todd Thompson (Ohio State U.) Francis Halzen (U. of Wisconsin, Madison) Abigail Vieregg (U. of Chicago) Fiona Harrison (Caltech) Stephan Zimmer (U. of Geneva) Xiangdong Ji (Shanghai Jiao Tong U.) Kathryn Zurek (LBNL) Marc Kamionkowski (Johns Hopkins U.) Conveners Neutrinos: Markus Ahlers (NBI), Amy Connolly (Ohio State), Ke Fang (UMD), Sergio Palomares-Ruiz (IFIC) Cosmic rays: Ilias Cholis (Johns Hopkins), Foteini Oikonomou (Penn State), Nahee Park (U. Chicago), Michael Sutherland (OSU) Gamma rays: Marco Ajello (Clemson U.), Andrea Albert (SLAC), Michelle Hui (NASA), Yoshiyuki Inoue (JAXA) Multi-messenger: Shin'ichiro Ando (GRAPPA), Kohta Murase (Penn State), Maria Petropoulou (Purdue U.), Amanda Weinstein (Iowa State) Dark matter: Francesca Calore (CNRS), Eric Dahl (Northwestern U.), Kerstin Perez (MIT), Ben Safdi (U. of Michigan) Galactic sources: Yves Gallant (LUPM), Elena Orlando (Stanford), Pablo Saz Parkinson (Hong Kong U.), Pat Slane (Harvard) Extragalactic sources: Jay Gallagher (U. of Wisconsin, Madison), Vasiliki Pavlidou (U. of Crete), Emma Storm (GRAPPA), Tuguldur Sukhbold (OSU) Particle physics: Nicole Bell (U. Melbourne), Pavel Fileviez Perez (CWRU), Tongyan Lin (LBL), Haibo Yu (U. of California, Riverside) Cosmology: Martina Gerbino (Stockholm U.), Tom Giblin (Kenyon College), Dragan Huterer (U. of Michigan), Gordan Krnjaic (Perimeter Institute) Committees  Local Organizing Committee International Advisory Committee Katie Auchettl - Co-chair Felix Aharonian (DIAS & MPIK) John Beacom Laura Baudis (U. of Zurich) Mauricio Bustamante - Co-chair John Beacom (Ohio State U.) Tim Linden - Co-chair Lars Bergstrom (U. of Stockholm) Annika Peter Gianfranco Bertone (U. of Amsterdam) - Chair Elliott Bloom (KIPAC-SLAC) Marco Cirelli (LPTHE Jussieu, Paris) Joakim Edsjo (U. of Stockholm) Jonathan Feng (UC Irvine) Gian Giudice (CERN) Sunil K. Gupta (TIFR) Francis Halzen (U. of Wisconsin, Madison) Dan Hooper (Fermilab) Olga Mena (IFIC/CSIC-UV) Subir Sarkar (Oxford & NBI Copenhagen) Tim Tait (UC Irvine) Masahiro Teshima (ICRR) Registration Participant registration Participants • Aaron Pierce • Abhishek Mohapatra • Abigail Vieregg • Aishwarya Srivastava • Alan Coleman • Alex Drlica-Wagner • Alex McDaniel • Alexander Natale • Alexander van Engelen • Alexandra Davis • Alexandra Rahlin • Ali Kheirandish • Allan Hallgren • Amanda Weinstein • Ami Choi • Amy Connolly • Andrea Albert • Andrea Münster • Andreas Bachlechner • Andres Medina • Andrew Fogelis • Andrew Long • Andrew Ludwig • Angela Olinto • Anna Barnacka • Anna Kwa • Anna Nierenberg • Anne Zilles • Annika Peter • Anthony Readhead • Antonia Hubbard • Antonio Boveia • Asher Berlin • Ashley Ross • Azadeh Keivani • B. Theodore Zhang • Barbara Ryden • Barmak Shams Es Haghi • Bei Zhou • Ben Margalit • Ben Wibking • Benjamin Buckman • Benjamin Kreis • Benjamin Safdi • Biao Wang • Bibhushan Shakya • Binita Hona • Björn Eichmann • Brian Clark • Brian Humensky • Bryan Reynolds • Carl Pfendner • Carlos Arguelles • Carlos Blanco • Carsten Rott • Caterina Doglioni • Chad Finley • Chih-Liang Wu • Chris Hill • Christopher Cappiello • Christopher Hirata • Christopher Kochanek • Christopher Persichilli • Chung-Lin Shan • Colin Turley • Collin Farquhar • Corbin Covault • Cosmin Deaconu • Daan van Eijk • Damiano Caprioli • Dan Hooper • Daniel Biehl • Daniel Dutcher • Daniel Fiorino • Daniel Pfeffer • Daniel Scolnic • Daniel Shafer • Daniel Siegel • Daniele Gaggero • Daniella Roberts • David Curtin • David Robertson • David Weinberg • Demetrius Tuggle • Dimitrios Giannios • Donald Ellison • Donghui Jeong • Donglian Xu • Dragan Huterer • Edoardo Maria Farina • Elena Orlando • Elisabeth Krause • Emma de Oña Wilhelmi • Emma Storm • Emrah Tiras • Eric Braaten • Eric Dahl • Eric Oberla • Eric Zirnstein • Esra Bulbul • Estefany Nunez • Eugenio Bottacini • Evan Bucklin • Evan Johnson • Federico Nati • Fiona Harrison • Floyd Stecker • Foteini Oikonomou • Francesca Calore • Francesca Giovacchini • Francesco Capozzi • Francesco Forastieri • Francis Halzen • Francis-Yan Cyr-Racine • Gabriel Vasquez • Gaia Vanzo • Galo Gallardo Romero • Gareth Hughes • Gianluca Gregori • Giovanni M. Piacentino • Guanying Zhu • Gustavo Otero Y Garzon • Gwenael Giacinti • Hai-Bo Yu • Hans Niederhausen • Hao-Yi Wu • Hiren Patel • Hitoshi Murayama • Hongwan Liu • Hugo Ayala • Hui Kong • Humberto Gilmer • Ibrahim Safa • Ievgen Vovk • Ilias Cholis • Ioannis Myserlis • Isabel Oldengott • J. Colin Hill • Jacob Gordon • Jae Hyeok Chang • Jahmour Givans • Jaime Ruz Armendariz • James Beatty • James DeLaunay • James T. Linnemann • Jarrett Moon • Jatan Buch • Javier Mauricio Duarte • Jeremy Perkins • Jezabel R. García • Jianjie Zhang • Jo Bovy • Joachim Brod • Joel Zinn • Johanna Nagy • John Beacom • John Farmer • John Gallagher • John Hewitt • John Tomsick • Johnathon Jordan • Jonathan Brown • Jonathan Cornell • Jonathan Davis • Jordan Myslik • Jordan Potter • Jordi Salvado • Jorge Casaus • Jorge Torres • Joseph Bramante • Joseph J DeVito • Joshua Foster • Joshua Hiltbrand • Joshua Wood • Julia Katharina Vogel • Julia Tjus • Justin Shortino • Justin Vandenbroucke • Kalel Alsaeed • Karthik Ramanathan • Katelin Schutz • Kathryn Zurek • Katie Auchettl • Kazumi Kashiyama • Ke Fang • Keith Bechtol • Keith McBride • Kelly Malone • Kenny Chun Yu Ng • Kerstin Perez • Khalida Hendricks • Kimberly Boddy • Kimmy Wu • Kirsten Casey • Kohta Murase • Konstancja Satalecka • Laura Chang • Lina Necib • Linda Carpenter • Liz Kruesi • Lorenzo Marafatto • Lu Lu • Lucas Smith • Lukas Merten • Macy Huston • Manuel Meyer • Marc Kamionkowski • Marek Kowalski • Maria Petropoulou • Mariangela Lisanti • Markus Ahlers • Martin Stref • Martina Gerbino • Mary Hall Reno • Masahiro Takimoto • Massimiliano Lattanzi • Matteo Cerruti • Matteo Duranti • Matthew Digman • Matthew Strait • Matthew Szydagis • Matthias Lorentz • Mattia Di Mauro • Mauricio Bustamante • Mehr Un Nisa • Melanie Heil • Michael Kovacevich • Michael Sutherland • Michelle Hui • Miguel Escudero • Miguel Mostafa • Mike Kroll • Mike Richman • Moritz Hütten • Nachiketa Chakraborty • Nahee Park • Nancy Wandkowsky • Nassim Bozorgnia • Natalie Harrison • Nathaniel Tagg • Neil Goeckner-Wald • Nepomuk Otte • Ness Mayker • Nicholas Rodd • Nicole Bell • Nicole Hess • Nicole Man • Niki Klop • Nima Arkani-Hamed • Nirmal Raj • Norita Kawanaka • Oindree Banerjee • Olga Botner • Olivier Martineau • Omid Sameie • Oscar Macias • Pablo Saz Parkinson • Patrick Allison • Patrick Fitzpatrick • Patrick Slane • Paul Sutter • Paulo Montero Camacho • Pavel Fileviez Perez • Payel Kar • Peter Denton • Petra Huentemeyer • Qing Lin • Qingwen Tang • Rachel Mandelbaum • Radomir Smida • Raffaella Margutti • Ralph Richard Engel • Ranjan Dharmapalan • Ranjan Laha • Richard Bartels • Richard Miller • Richard Shaw • Rishabh Khandelwal • Rob Halliday • Robert Scherrer • Rui Wang • Russell Colburn • Ryan Edward Keeley • Ryan Farber • Ryan Thomas • Ryosuke Itoh • Ryosuke Sato • Samaya Nissanke • Samuel Marinelli • Sandip Pakvasa • Sanskriti Das • Sarah Mancina • Sarah McCleskey • Sarah Recchia • Saroj Adhikari • Saurabh Kumar • Savvas Koushiappas • Scott Fallows • Scott Locke • Scott Wakely • Sebastian Ingenhütt • Sergio Palomares-Ruiz • Shafeeq Rahman Thottoli • Shashank Jayakumar • Sheldon Campbell • Shigeo Kimura • Shin'ichiro Ando • Shirley Li • Siddharth Mishra-Sharma • Simon Kast • Srividya Suresh • Stacy Kim • Stefan Vogl • Stephan Zimmer • Stephanie Wissel • Stuart Raby • Sujeong Lee • Sunit Patil • Suren Gourapura • Szabolcs Marka • Takahiro Sudoh • Takashi Sako • Takashi Toma • Tansu Daylan • Tareq AbuZayyad • Thomas Fitoussi • Thomas Gaisser • Thomas Weiler • Thomas Weisgarber • Tianlu Yuan • Tim Huege • Tim Linden • Todd Thompson • Tolga Yapici • Tom Brantseg • Tom Giblin • Tonia Venters • Tova Yoast-Hull • Tracy Slatyer • Troy Porter • Tsuguo Aramaki • Tuguldur Sukhbold • Tyce DeYoung • Tyler White • Vasiliki Pavlidou • Vedran Brdar • Veronica Bindi • Victoria Kaspi • Vikram Dwarkadas • Wei-Hao Lai • Wendy Taylor • William Wester • Xavier Rodrigues • Xiangdong Ji • Xiao Fang • Xilu Wang • Yasuyuki Tanaka • Ying Zu • Yoichi Asaoka • Yong Yang • Yongchao Zhang • Yoshiyuki Inoue • Yu-Dai Tsai • Yuan-Hann Chang • Yue Zhang • Yves Gallant • Zachary Griffith • Zachary Slepian • ZJ Poh Contact • Sunday, August 6 • 10:00 AM 10:30 AM Welcome OSU Physics Research Building #### OSU Physics Research Building • 10:30 AM 5:00 PM Mini-workshops OSU Physics Research Building #### OSU Physics Research Building Topics to be defined Conveners: Alex Drlica-Wagner (Fermilab), Annika Peter (Ohio State University), Antonio Boveia (Ohio State University), Azadeh Keivani (The Pennsylvania State University), Carl Pfendner, Caterina Doglioni (Lund University (SE)), Cosmin Deaconu (UChicago), Dr Daniel Fiorino (University of Maryland College Park), Keith Bechtol (LSST), Kimberly Boddy (University of Hawaii), Lu Lu (Chiba University), Nassim Bozorgnia (GRAPPA, University of Amsterdam), Nicholas Rodd (Massachusetts Institute of Technology), Dr Norita Kawanaka (Kyoto University), Olivier Martineau (CNRS), Oscar Macias (Virginia Tech), Radomir Smida (Karlsruhe Institute of Technology), Ranjan Laha (Stanford University), Savvas Koushiappas (Brown University), Prof. Stephanie Wissel (Cal Poly), dan hooper, mattia di mauro (Stanford University) • 10:30 AM Morning discussion 2h • 12:30 PM Lunch 1h 30m • 2:00 PM Afternoon discussion 3h • Monday, August 7 • 8:00 AM 9:00 AM Welcome: Registration Davidson Theatre #### Davidson Theatre • 9:00 AM 9:10 AM Welcome: Opening remarks Davidson Theatre #### Davidson Theatre Convener: John Beacom (Ohio State University) • 9:00 AM Opening remarks 10m Speaker: John Beacom (Ohio State University) • 9:10 AM 12:10 PM Plenary session Davidson Theatre #### Davidson Theatre Conveners: John Beacom (Ohio State University), Tim Linden • 9:10 AM Challenges of particle physics theory 30m TBD Speaker: Nima Arkani-Hamed (IAS) • 9:40 AM Galactic cosmic ray sources: a multimessenger view 30m In this talk, the current state-of-the-art on our knowledge and ignorance of galactic cosmic ray sources will be presented. In particular, cosmic ray observables from MeV to (super-)PeV will be presented. This concerns a (potentially) direct view on the sources via ionization signatures, neutrinos and gamma-rays as well as those pieces of information provided by cosmic rays themselves, i.e. spectrum, composition and anisotropy. The latter heavily relies on the transport properties through the magnetized plasma of the interstellar medium, which will be a special focus of the talk. The different methods for Galactic propagation will be reviewed in the context of the interpretation of the data, discussion in particular the role of the diffusion tensor and advection and their contributions to a possible Galactic wind. Speaker: Julia Tjus • 10:10 AM Coffee break 30m Davidson Theatre #### Davidson Theatre • 10:40 AM Indirect Searches for Dark Matter 30m I will review the current status of indirect dark matter searches, and discuss possible future directions. Speaker: Tracy Slatyer • 11:40 AM Hidden-sector dark matter 30m We discuss the paradigm of dark matter from a hidden sector, and observational implications for colliders and direct detection experiments. Speaker: Kathryn Zurek (LBNL) • 12:10 PM 2:00 PM Lunch 1h 50m • 2:00 PM 3:30 PM Cosmic rays Macedonian Room (The Athenaeum) ### Macedonian Room #### The Athenaeum Convener: ILIAS CHOLIS (Johns Hopkins University) • 2:00 PM High-Energy Gamma-Rays from the Milky Way: Three-Dimensional Spatial Models for the Cosmic-Ray and Radiation Field Densities 15m High-energy gamma rays of interstellar origin are produced by the interaction of cosmic-ray (CR) particles with the diffuse gas and radiation fields in the Galaxy. The main features of this emission are well-understood and are reproduced by existing CR propagation models employing 2D Galactocentric cylindrically symmetrical geometry. However, the high-quality data from instruments like the Fermi Large Area Telescope reveal significant deviations from the model predictions on few to tens of degree scales indicating the need to include the details of the Galactic spiral structure and thus require 3D spatial modelling. In this contribution the high-energy interstellar emissions from the Galaxy are calculated using the newly released version of the GALPROP code (v55) employing 3D spatial models for the CR source and interstellar radiation field (ISRF) densities. The interstellar emission models that include arms and bulges for the CR source and ISRF densities provide plausible physical interpretations for features found in the residual maps from high-energy gamma-ray data analysis. The 3D models for CR and ISRF densities provide a more realistic basis that can be used for refined interpretation of the non-thermal interstellar emissions from the Galaxy. Speaker: Troy Porter (Stanford University) • 2:15 PM Propagation of TeV-energy cosmic rays using stochastic differential equations in CRPropa3.1 15m The propagation of charged cosmic rays through the Galactic environment influences all aspects of the observation at Earth. Energy spectrum, composition and anisotropy are changed due to deflections in magnetic fields and interactions with the interstellar medium. Today the transport is simulated with different simulation methods either based on the solution of a transport equation (multi-particle picture) or a solution of an equation of motion (single-particle picture). We developed a new module for the publicly available Propagation software CRPropa3.1, where we implemented an algorithm to solve the transport equation using stochastic differential equations. This technique allows us to use a diffusion tensor which is anisotropic with respect to an arbitrary magnetic background field, such as the well-known JF12 field. In this contribution, we present first studies on the influence of a anisotropic diffusion along the magnetic field line on the cosmic ray outflows and compare our results to observations. Speaker: Lukas Merten (Ruhr-University Bochum) • 2:30 PM Multi-wavelength Signatures of Cosmic Rays in the Milky Way 15m Cosmic rays propagate in the Milky Way and interact with the interstellar medium and magnetic fields. These interactions produce emissions that span the electromagnetic spectrum and are an invaluable tool for understanding the intensities and spectra of cosmic rays in different regions of the Milky Way. Hence observations of these emissions complement information from cosmic ray measurements. We present updates on the study of cosmic ray properties by combining multi-wavelength observations of this interstellar emission with latest accurate CR direct measurements. Speaker: Elena Orlando (Stanford University) • 2:45 PM Solar Modulation studies with the Alpha Magnetic Spectrometer 15m The Alpha Magnetic Spectrometer (AMS), on the International Space Station (ISS) since May 2011, has acquired the largest number of particles ever measured in space by a single experiment, performing the most precise measurement of galactic cosmic rays (GCR) to-date. The detailed time variation of multiple particle species fluxes measured in the first years of operations, during the ascending phase of solar cycle 24 and reversal of the Sun's magnetic field polarity (from negative A < 0 to positive A > 0). For all particles, the high energy spectrum remains stable versus time, while the low-energy range is strongly modulated by the solar activity. In addition, AMS measured several Forbush decreases (FD) and solar energetic particles (SEP) associated with the short term solar activity. Speaker: Veronica Bindi (University of Hawai'i at Manoa (US)) • 3:00 PM Cosmic ray propagation around the Sun 15m The Sun shadow can be measured with the IceCube detector and varies in depth corresponding to the magnetic field. Hence, we are given a possibility to understand cosmic ray propagation in the magnetic field of the Sun, for which a sufficiently good modelling is necessary. We investigate the field with its temporal deviations in strength and orientation. In times of low solar activity, the field can be approximated by a dipole structure. During higher activities, however, the field becomes increasingly inhomogeneous, especially in regions near the solar surface. These regions are spatially constrained and can reach magnetic field strengths of up to 50 Gauss. In this work, we simulate protons with energies up to Ep, max = 40 TeV. This energy is the median energy of those cosmic rays that are used in IceCube’s Sun shadow analysis. Its data allows to determine the Sun shadow at different times in the solar cycle and compare the results to our simulation. We obtain solar magnetic field data within the PFSS model from the GONG data archive. Speaker: Mike Kroll (Ruhr-Universität Bochum) • 3:15 PM Observation of the Moon and Sun with HAWC 15m The Sun and Moon produce deep deficits in the nearly isotropic flux of TeV cosmic rays measured at Earth. Observations of these cosmic-ray deficits, or "shadows," can provide unique measurements of the solar and Galactic environment. For example, the displacement of the shadow of the Moon in the geomagnetic field allows for charge discrimination of high-energy Galactic cosmic rays. The Sun shadow varies strongly with the solar cycle, and multi-year measurements enable precise tests of coronal magnetic field models. Moreover, the Sun may also be a TeV gamma ray source due to interactions of Galactic cosmic rays in its photosphere. The High Altitude Water Cherenkov (HAWC) Observatory, a wide field-of-view detector of TeV cosmic rays and gamma rays, performs unbiased high-statistics measurements of the Sun and Moon each day. Using measurements of the Moon shadow with two years of data from the complete HAWC array, we will present strong limits on the flux of antiprotons above 1 TeV. We will also present the first upper limits on the flux of gamma rays above 1 TeV from the solar disk. Speaker: Mehr Un Nisa (University of Rochester) • 2:00 PM 3:30 PM Cosmology Spartan Room (The Athenaeum) ### Spartan Room #### The Athenaeum Convener: Martina Gerbino • 2:00 PM Observing the Polarization of the Cosmic Microwave Background with SPIDER 15m SPIDER is a balloon-borne telescope designed to characterize the linear polarization of the cosmic microwave background at degree angular scales, and in particular to place constraints on the$B$-mode angular power spectrum arising from primordial gravitational waves. For the inaugural flight in January 2015, SPIDER observed approximately 12% of the sky with nearly 2000 detectors at frequencies of 95 GHz and 150 GHz in order to characterize the CMB power spectrum over the range$30 < \ell < 300$. In combination with Planck data at higher frequencies, the relatively large sky coverage over multiple frequency bands also enables characterization of foreground contributions from Galactic dust. A second flight in December 2018 will include several high-frequency instruments to further constrain Galactic foregrounds in our region of the sky. In this talk, we present preliminary analysis of data from the first flight, as well as science prospects for the second flight. Speaker: Alexandra Rahlin (Fermi National Accelerator Laboratory) • 2:15 PM A New Limit on CMB Circular Polarization from SPIDER 15m I will present a new upper limit on CMB circular polarization from the 2015 flight of SPIDER, a balloon-borne telescope designed to search for B-mode linear polarization from cosmic inflation. Although the level of circular polarization in the CMB is predicted to be very small, experimental limits provide a valuable test of the underlying models. By exploiting the non-zero circular-to-linear polarization coupling of the half-wave plate polarization modulators, data from SPIDER's 2015 Antarctic flight provides a constraint on Stokes V at 95 and 150 GHz from 33 < l < 307. No other limits exist over this full range of angular scales, and SPIDER improves upon the previous limit by several orders of magnitude. As linear CMB polarization experiments become increasingly sensitive, similar techniques can be applied to obtain even stronger constraints on circular polarization. Speaker: Dr Johanna Nagy (Case Western Reserve University) • 2:30 PM SPT-3G: A new instrument on the South Pole Telescope 15m The South Pole Telescope is a 10-meter diameter telescope located at the NSF Amundsen-Scott South Pole Station in Antarctica, designed for high-precision measurements of the temperature anisotropy and polarization properties of the cosmic microwave background. The third-generation camera on the telescope, SPT-3G, was deployed in the 2016-2017 austral summer season and represents a significant technological upgrade over previous instruments. The secondary optics, receiver cryostat, readout electronics, and detectors have all been redesigned and replaced with significantly improved versions. The SPT-3G focal plane consists of over 2700 trichroic, dual-polarization pixels with observing bands centered at 95, 150, and 220 GHz for a total of over 15,000 detectors on-sky. The higher detector count and larger focal plane footprint will yield a ~20x faster mapping speed and ~5x lower noise compared to the previous camera, SPTpol. The increased sensitivity and resolution of SPT-3G will yield high signal-to-noise maps of lensing B-modes, and when combined with other experiments could constrain the sum of the neutrino masses to within 0.06 eV, directly probing the neutrino mass hierarchy. I will discuss the technology of the upgraded instrument, its installation onto the telescope, and what we’ve learned in the few months since deployment. Speaker: Daniel Dutcher (Kavli Institute for Cosmological Physics, University of Chicago & Department of Physics, University of Chicago) • 2:45 PM Measuring the Cosmic Microwave Background B-mode Polarization with the POLARBEAR Experiment 15m The odd-parity (B-mode) polarization anisotropy of the Cosmic Microwave Background (CMB) provides a unique window into the history and contents of the universe. At sub-degree scales this polarization is primarily created by the gravitational lensing of the CMB due to intervening large scale structure while at degree scales B-mode polarization can indicate the presence of primordial gravitational waves predicted by the theory of inflation. We present an update on the analysis of data taken by the POLARBEAR experiment. We show the B mode power spectrum inferred from two seasons of data taken between 2012 and 2014 on an effective sky area of 25 square degrees over a range of multipole moments$500 \leq \ell \leq 2100$. The measured amplitude of lensing B modes after subtraction of galactic foregrounds is found to be$A_L = 0.60 ^{+0.26} _{-0.24} ({\rm stat}) ^{+0.00} _{-0.04}({\rm inst}) \pm 0.14 ({\rm foreground}) \pm 0.04 ({\rm multi})$where$A_L = 1$corresponds to$\Lambda CDM$cosmology. In mid 2014 POLARBEAR deployed a continuously rotating half wave plate polarization modulator and began scanning a 700 effective square degree patch to measure degree angular scale B-mode polarization. We present the status of this analysis and outline considerations for future experiments designed to operate in this configuration including the Simons Array and Simons Observatory. Speaker: NEIL GOECKNER-WALD (University of California Berkeley) • 3:00 PM High Accuracy Calibration Sources for Cosmic Microwave Background Polarimeters: POLOCALC 15m I will describe a novel method to measure the absolute orientation of the polarization plane of the CMB with arcsecond accuracy, that will enable unprecedented measurements for cosmology and fundamental physics. Existing and planned CMB polarization instruments looking for primordial B-mode signals need an independent, experimental method for systematics control on the absolute polarization orientation. The lack of such a method limits the accuracy of the detection of inflationary gravitational waves, the constraining power on the neutrino sector through measurements of gravitational lensing of the CMB, the possibility of detecting Cosmic Birefringence, and the ability to measure primordial magnetic fields. Sky signals used for calibration and direct measurements of the detector orientation cannot provide an accuracy better than 1 deg. Self-calibration methods provide better accuracy, but may be affected by foreground signals and rely heavily on model assumptions. The POLarization Orientation CALibrator for Cosmology, POLOCALC, will dramatically improve instrumental accuracy by means of an artificial calibration source flying on balloons and aerial drones. A balloon-borne calibrator will provide far-field source for larger telescopes, while a drone will be used for tests and smaller polarimeters. POLOCALC will also allow a unique method to measure the telescopes' polarized beam. It will use microwave emitters between 40 and 150 GHz coupled to precise polarizing filters. The orientation of the source polarization plane will be registered to sky coordinates by star cameras and gyroscopes with arcsecond accuracy. Any CMB experiment observing our calibrator will enable measurements of the polarization angle in absolute sky coordinates. Speaker: Dr Federico Nati (University of Pennsylvania) • 3:15 PM Status and Recent Results from the BICEP Suite of Experiments at the South Pole 15m Increasingly precise maps of the polarization of the CMB are a unique and powerful tool for understanding new physics, including inflation, the superluminal expansion of the universe during the first moments after the Big Bang. I will discuss constraints on inflation, set using the BICEP series of experiments at the South Pole (BICEP2, The Keck Array, and BICEP3). I will then discuss projections for the future of the BICEP program, including BICEP Array. Speaker: Prof. Abigail Vieregg (University of Chicago) • 2:00 PM 3:30 PM Dark matter Small Theater (The Athenaeum) ### Small Theater #### The Athenaeum Convener: Lina Necib (MIT) • 2:00 PM Diverse Galactic Rotation Curves and Self-Interacting Dark Matter 15m The rotation curves of spiral galaxies exhibit a diversity that has been difficult to understand in the cold dark matter (CDM) paradigm. In this talk, I will show that the self-interacting dark matter (SIDM) model provides excellent fits to the rotation curves of a sample of galaxies with asymptotic velocities in the 25 to 300 km/s range that exemplify the full range of diversity. We only assume the halo concentration-mass relation predicted by the CDM model and a fixed value of the self-interaction cross section. The impact of the baryons on the SIDM halo profile and the scatter from the assembly history of halos as encoded in the concentration-mass relation can explain the diverse rotation curves of spiral galaxies. I will also discuss other smoking-gun signatures of SIDM in astrophysical observations. Speaker: Hai-Bo Yu (University of California, Riverside) • 2:15 PM Can Self-interacting Dark Matter Solve the 'Diversity Problem' in Galactic Rotation Curves? 15m While the$\Lambda$CDM paradigm has been extremely successful in matching observations of dark matter structure at large scales, several discrepancies between observations of dark matter structures at smaller scale (galactic and below) and$\Lambda$CDM's predictions have motivated particle physicists to consider an self-interacting dark matter (SIDM) as a possible solution. In this talk I will focus on how SIDM may solve the so-called 'diversity problem', in which the wide range of dark matter density profiles as inferred through the rotation curves of nearby galaxies are difficult to reproduce through baryonic feedback in$\Lambda$CDM. SIDM allows for a wide range of scatter in the core sizes of dark matter halos in the following ways: (1) Collisional scatterings between dark matter particles thermalize the inner regions of the dark matter halo and let its density profile adjust in response to the baryonic gravitational potential; and (2) scatter in the concentration-mass relation leads to scatter in the halo core size at fixed halo mass. Taking these two effects into account ,we fit the SIDM scattering cross section and galaxy parameters for nearby galaxies in the SPARC sample. We find a clear preference for the SPARC rotation curves to be fit with SIDM cross sections >$\mathcal{O}(0.1)$cm$^2$/g. Speaker: Anna Kwa (UC Irvine) • 2:30 PM Constraining Self-Interacting Dark Matter through Equal Mass Galaxy Cluster Mergers 15m While the LCDM model has been wildly successful at explaining structure on large scales, it fails to do so on small scales---dark matter halos of scales comparable to that of galaxy clusters and smaller are more cored and less numerous than LCDM predicts. One potential solution challenges the canonical assumption that dark matter is collisionless and instead assumes that it is self-interacting. The most stringent upper limits on the dark matter self-interaction cross section have come from observations of merging galaxy clusters. Self-interactions cause the merging dark matter halos to evolve differently from the galaxies, which are effectively collisionless. It has been hypothesized that this leads to a spatial offset between the peaks in the dark matter and galaxy distributions. We show that in equal mass mergers, offsets matching those observed do not develop except under a narrow range of merger conditions that promote extreme dark mass loss during collision. Furthermore, offset formation cannot be described by a drag force nor by tail formation alone, as has previously been claimed. Self-interactions have a significant influence on other aspects of merger evolution, which can be exploited to derive stronger constraints on the self-interaction cross section. In particular, we expect a large fraction of BCGs to be miscentered by order 100s of kpc with cross sections greater than 1 cm^2/g; the lack of such large miscenterings implies a cross section no larger than 0.1 cm^2/g. Speaker: Stacy Kim (Ohio State University) • 2:45 PM SIMPs with Vector Mediators 15m A general mechanism for thermal production of dark matter (DM) via 3-to-2 scatterings, or other higher-order interactions, allows for sub-GeV dark matter and strong self-interactions that meet existing constraints but have the potential to explain mysteries with cold DM and structure formation. In such models, so-called Strongly Interacting Massive Particles (SIMPs), a correct thermal average is important. These SIMP mechanism can exist in models with multiple scalars or in a strongly coupled gauge theory where the Weiss-Zumino-Witten term generates the 3-to-2 interaction. Particularly, a two-scalar model with a residual$Z_5$discrete symmetry and a model with a dark QCD sector can produce parameter spaces where the SIMP paradigm is realized. In both models, the importance of vector mediators in the SIMP mechanism, and how these vector mediators affect the thermal average, is discussed. Speaker: Alexander Natale (Korea Institute for Advanced Study) • 3:00 PM Enabling Forbidden Dark Matter 15m The thermal relic density of dark matter is conventionally set by two-body annihilations. We point out that in many simple models, 3→2 annihilations can play an important role in determining the relic density over a broad range of model parameters. This occurs when the two-body annihilation is kinematically forbidden, but the 3→2 process is allowed; we call this scenario "Not-Forbidden Dark Matter". We illustrate this mechanism for a vector portal dark matter model, showing that for a dark matter mass of mχ ∼ MeV - 10 GeV, 3→2 processes not only lead to the observed relic density, but also imply a self-interaction cross section that can solve the cusp/core problem. This can be accomplished while remaining consistent with stringent CMB constraints on light dark matter, and can potentially be discovered at future direct detection experiments. Speaker: Hongwan Liu (Massachusetts Institute of Technology) • 3:15 PM Chiral Effective Theory of Dark Matter Direct Detection 15m The existence of dark matter is one of the few solid hints for physics beyond the standard model. If dark matter has indeed particle nature, then direct detection via scattering on atomic nuclei is one of the most promising discovery channels. In order to connect this nonrelativistic process with astrophysical and collider searches, as well as UV model building, a consistent setup of effective field theories for the different energy scales is necessary. I will present our work on the explicit connection between these energy scales, from the UV down to the nuclear scale. I will, in particular, discuss previously neglected chiral effects that can change the cross section by more than an order of magnitude. Speaker: Joachim Brod (TU Dortmund) • 2:00 PM 3:30 PM Gamma rays Corinthian Room (The Athenaeum) ### Corinthian Room #### The Athenaeum Convener: Michelle Hui • 2:00 PM Very High Energy Astrophysics with VERITAS 15m For more than a decade VERITAS, an imaging atmospheric-Cherenkov telescope array, has been probing the Northern very-high-energy (VHE; >100 GeV) gamma-ray sky. Located in Southern Arizona, VERITAS consists of four 12-m diameter reflectors and is one of the worlds most sensitive detectors of gamma rays between 85-GeV to 30-TeV. Over 50 galactic and extra-galactic sources have been detected at these energies many in conjunction with multi-wavelength and multi-messenger partners. Areas of investigation include the acceleration and propagation of cosmic rays in both galactic and extra-galactic sources, fundamental physics topics including the study of dark matter candidates, and an active multi-messenger follow up program for triggers received from electromagnetic, neutrino, and gravitational wave partners. Speaker: Dr Gareth Hughes (Harvard-Smithsonian CFA) • 2:15 PM Highlights from MAGIC 30m For more than a decade the MAGIC Collaboration is delivering outstanding results in the field of very high energy gamma-ray physics. The two 17m telescope system is one of the best performing instruments in its class, especially at low energies, crucial for observations of e.g. high redshift sources, pulsars and GRBs. This talk will discuss recent key results from Galactic and extragalactic observation campaigns, including our fundamental physics (e.g. dark matter, Lorentz Invariance Violation) and cosmic ray (e.g. earth-skimming tau-neutrinos) programs. The basic instrumental features and challenges will also be presented. Finally, a perspective on the future of the experiment will be given. Speaker: Dr Konstancja Satalecka (DESY Zeuthen, Germany) • 2:45 PM An energy cutoff in the TeV gamma ray spectrum of the SNR Cassiopeia A 15m It is widely believed that Galactic Cosmic Rays (CR) are accelerated in Supernova Remnants (SNRs) through the process of diffusive shock acceleration. In this scenario, particles should be accelerated up to energies around 1 PeV (the so-called 'Knee') and emit gamma rays. To test this hypothesis, precise measurements of the gamma-ray spectra of young SNRs at TeV energies are needed. Among the already known SNRs, Cassiopea A (Cas A) appears as one of the best candidates for such studies. It is relatively young (about 300 years) and it has been largely studied in radio and X-ray bands, which constrains essential parameters for testing emission models, such as the magnetic field. We will present the results of a multi-year campaign of Cas A with the MAGIC Imaging Atmospheric Cherenkov Telescopes for a total of 158 hours of good-quality data. We obtained a spectrum of the source from 100 GeV to 10 TeV and fit it assuming it follows a power-law distribution, with and without an exponential cut-off. We found, for the first time in Very High Energy (VHE, E>100GeV), observational evidence for the presence of a cut-off in Cas A. Assuming that TeV gamma rays are produced by hadronic processes and that there is no significant cosmic ray diffusion, this indicates that Cas A is not a PeVatron (PeV accelerator) at its present age. Speaker: Emma de Ona Wilhelmi (CSIC-IEEC) • 3:00 PM A First Look at the Very Highest-Energy Gamma-Ray Sky from HAWC 15m TeV observations of gamma-ray sources are very important probes of cosmic-ray accelerators, as leptonic and hadronic spectra differ in this energy range. The High Altitude Water Cherenkov (HAWC) Observatory, located in Puebla, Mexico, is capable of detecting air showers initiated by gamma rays in the multi-TeV energy range. The upper end of this range is previously unexplored. The detector consists of 300 water Cherenkov tanks located at an altitude of 4100m, each instrumented with 4 PMTs. Because its instantaneous field of view is ~2sr and it has a duty cycle > 95% percent, the array is well-suited to performing all-sky surveys. I will present a method to reconstruct energy of the primary gamma rays on an event-by-event basis by measuring the charge density as a function of distance to the air shower axis. This greatly improves the dynamic range compared to the current method used by HAWC, which assigns a mean energy value for all events of a given shower size. I will use the method to show the latest HAWC observations of gamma-ray sources above 50 TeV, which are among the highest-energy gamma rays ever studied. Speaker: Kelly Malone (Pennsylvania State University) • 3:15 PM Search for PeV Photons with IceTop and IceCube 15m We present results of a search for galactic PeV gamma rays with the IceCube observatory, presently the most sensitive facility for PeV gamma-ray sources in the Southern Hemisphere. This includes a search for point sources over IceCube’s field of view, as well as tests for correlations with TeV sources detected by H.E.S.S. and neutrino events from IceCube’s high energy starting event sample, with the goal to constrain the Galactic component to the astrophysical neutrino flux observed by IceCube. In addition, we search for correlations of PeV gamma rays with the Galactic plane, using the pion decay component of the Fermi-LAT diffuse emission model as a spatial template. As cosmic rays producing such gamma rays are necessarily an order of magnitude greater in energy, this result provides a new constraint on the galactic source contribution to the cosmic ray flux above the “knee”. Speaker: Zachary Griffith (IceCube Collaboration, University of Wisconsin - Madison) • 2:00 PM 3:30 PM Neutrinos Athenian Room (The Athenaeum) ### Athenian Room #### The Athenaeum Convener: Carsten Rott (Sungkyunkwan University) • 2:00 PM Observing supernova neutrinos to late times 15m The next Galactic supernova (SN) will probably occur while current or next generation neutrino experiments are online. It is crucial to have correct understanding of the basic characteristics of the expected neutrino signals. The nominal expectation of the duration of the neutrino signal is ~ 10 s; this expectation guided both theoretical and experimental effort. We simulate SN neutrino emission at late times and predict the detected neutrino signals in large neutrino experiments. We find that neutrino signals from a SN should be detected out to ~ 1 min. We will discuss how this will change future theoretical and experimental effort in SN studies. Speaker: Shirley Li (The Ohio State University) • 2:15 PM Neutrino flavour conversions near the supernova core 15m Supernova neutrinos can experience “fast” self-induced flavor conversions almost immediately above the core, with important implications for the explosion mechanism and nucleosynthesis. Very recently, a novel method has been proposed to investigate these phenomena, in terms of the dispersion relation for the complex frequency and wave number (ω, k) of disturbances in the mean field of the νe-νx flavour coherence. I discuss a systematic approach to such instabilities, originally developed in the context of plasma physics. Instabilities are typically seen to emerge for complex ω, and can be further characterized as convective (moving away faster than they spread) and absolute (growing locally), depending on k-dependent features. The analytical classification of both unstable and stable modes leads not only to qualitative insights about their features but also to quantitative predictions about the growth rates of instabilities. Speaker: Francesco Capozzi (The Ohio State University) • 2:30 PM Neutrino astronomy: Measuring the size of the Sun's core 15m I introduce the idea of using neutrinos as probes for measuring the size of the solar core. I review previous work showing that neutrinos from galactic supernovae, detected in water Cherenkov experiments such as Super Kamiokande, can be used to locate their sources. Using these ideas I discuss my recent work in Phys.Rev.Lett. 117 (2016) 211101 on the prospects for measuring the size of the solar core using 8B neutrinos, for Super Kamiokande and future experiments such as Hyper Kamiokande. I show using a maximum likelihood analysis, that it is possible to actually locate neutrino emission within the solar core with approximately 4 years of data from an experiment like Hyper Kamiokande. I am also submitting an abstract to the track Multi-messenger. Speaker: Dr Jonathan Davis (King's College London) • 2:45 PM Muon-induced spallation backgrounds in DUNE 15m Galactic supernovae are rare, just a few per century, so it is important to be prepared. If we are, then the long-baseline detector DUNE could detect thousands of events, compared to the tens from SN 1987A. An important question is backgrounds from muon-induced spallation reactions. We simulate particle energy-loss processes in liquid argon, and compare relevant isotope yields with those in the water-Cherenkov detector SuperK. Our approach will help optimize the design of DUNE and further benefit the study of supernova neutrinos. Speaker: Guanying Zhu (The Ohio State University) • 3:00 PM Showering Muons in Super Kamiokande 15m Super-Kamiokande (SK), the world's largest underground water Cherenkov detector, observes about 2 muons a second passing through it at a depth of 1 km. A fraction of these muons shower, and sometimes create radioactive isotopes (spallation). Those isotopes live anywhere from microseconds to several seconds, forming a dominant background to neutrino searches above 6 MeV and below 20 MeV. Detection of Cherenkov light from the showers points to the location of potential spallation products. Spallation is predominantly produced by neutrons and pions interacting with oxygen in the water. Therefore the detection of neutrons produced by muons serves both as an effective tag as well as an independent position measurement of spallation production. Recently, these neutrons were successfully detected in SK. The development of this technique may prove critical for future water Cherenkov detectors with less overburden, such as Hyper Kamiokande. The addition of water soluble gadolinium salt will improve the neutron detection efficiency and muon time correlation. Speaker: Mr Scott Locke (University of California, Irvine) • 3:15 PM Astrophysics with the NOvA neutrino experiment 15m NOvA is a long-baseline neutrino oscillation experiment with the primary goals of discovering CP violation in the neutrino sector, determining the neutrino mass hierarchy and constraining the mixing angle$\theta_{23}$. NOvA also has a rich program of cosmic ray and astrophysical measurements. We will set competitive limits on the flux of magnetic monopoles as well as for neutrinos resulting from dark matter annihilation in the Sun. Both the NOvA near and far detectors are capable supernova observatories. The NOvA near detector has confirmed a puzzling reversal, first seen by MINOS, of the usual seasonal trend of cosmic rays underground in the case of multiple muons. Several other astrophysical topics will also be discussed. Speaker: Dr Matthew Strait (University of Minnesota) • 3:30 PM 4:00 PM Coffee break 30m Oak Room (The Athenaeum) ### Oak Room #### The Athenaeum • 4:00 PM 6:00 PM Cosmic rays Macedonian Room (The Athenaeum) ### Macedonian Room #### The Athenaeum Convener: ILIAS CHOLIS (Johns Hopkins University) • 4:00 PM Latest results from AMS on the Space Station 30m The Alpha Magnetic Spectrometer (AMS) is a multi-purpose magnetic spectrometer measuring cosmic rays up to TeV energies on the International Space Station (ISS) since 2011. Its precision, large acceptance and ability to identify particle types over a wide energy range during its long duration mission in Space make it unique in astro-particle physics. To date AMS has collected over 100 billion charged cosmic ray events. The latest AMS results will be presented. Speaker: Melanie Heil (Massachusetts Inst. of Technology (US)) • 4:30 PM Antiproton Flux and Antiproton-to-Proton Flux Ratio in Primary Cosmic Rays Measured with AMS on the Space Station 15m Precision measurements by AMS of the antiproton flux and the antiproton-to-proton flux ratio in primary cosmic rays in the absolute rigidity range from 1 to 450 GV are presented based on$3.49 \times 10^5$antiproton events and$2.42 \times 10^9$proton events. At$~20$GV the antiproton-to-proton flux ratio reaches a maximum. Unexpectedly, above 60 GV the antiproton spectral index is consistent with the proton spectral index and the antiproton-to-proton flux ratio shows no rigidity dependence in the rigidity range from$~60$to$~500$GV. This unexpected observation requires new explanation of the origin of cosmic ray antiprotons. Speaker: Andreas Bachlechner (Rheinisch-Westfaelische Tech. Hoch. (DE)) • 4:45 PM Precision Measurement of the Combined Electron and Positron Flux in Primary Cosmic Rays with AMS on the ISS 15m We present the latest measurement of the combined electron and positron flux in cosmic rays based on the analysis of all the AMS data collected during more than 5 years of operations. The multiple redundant identification of electrons and positrons, and the match of energy measured by the 17 radiation lengths calorimeter and the momentum measured by the tracker in the magnetic field enable us to select a clean electron and positron sample up to the highest energies. The extensive calibration of the detector in the test beam at CERN verifies the energy scale and the proton rejection power. These latest results, based on twice the statistics of our previous publication, disagree with the results of other experiments, especially at high energies. Our results in the region from 30 to 1000 GeV can be described accurately by a single power law dependence. Speaker: Matteo Duranti (Universita e INFN, Perugia (IT)) • 5:00 PM Cosmic-Ray Lithium Production at a Type Ia Supernova Following a Nova Eruption 15m Recent direct measurements of cosmic-ray (CR) light nuclei (protons, helium, and lithium) by AMS-02 have shown that the flux of each element has an unexpected hard component above$\sim 300~{\rm GeV}$, and that the spectral indices of those components are almost the same. This implies that there are some primary sources that produce CR lithium nuclei, which have been believed to be produced via spallation of heavier nuclei in the ISM (secondary origin). We propose the nearby Type Ia supernova following a nova eruption from a white dwarf as the origin of CR Li. Speaker: Dr Norita Kawanaka (Kyoto University) • 5:15 PM Measurement of anisotropies in cosmic ray arrival directions with the Alpha Magnetic Spectrometer on the International Space Station 15m Analysis of anisotropies in the arrival directions of galactic protons, electrons and positrons has been performed by AMS on the International Space Station. An absolute anisotropy measurement has been performed with protons, electrons and positrons. These, together with the results of the anisotropy analysis of the electron to proton, positron to proton, and the positron to electron ratios will be presented. Speaker: Jorge Casaus (Centro de Investigaciones Energéti cas Medioambientales y Tecno) • 5:30 PM Properties of Elementary Particle Flux Ratios in Primary Cosmic Rays 15m We report the measurements of the fluxes of elementary particles: electrons, positrons, protons, and antiprotons, in the cosmic rays by the AMS experiment. The measured spectra show distinctive features that cannot be explained by ordinary cosmic ray models. In particular, in spite of the different production and propagation properties of protons, antiprotons and positrons, the antiproton-to-proton and positron-to-proton flux ratios are rigidity independent above 60 GV, while the electron flux shows completely different rigidity dependence. To explain these unexpected features, new understandings of elementary particles in the cosmic rays are needed. Speaker: Yuan-Hann Chang (National Central University (TW)) • 5:45 PM Cosmic ray driven winds in the Galactic environment and the cosmic ray spectrum 15m Cosmic Rays escaping the Galaxy exert a force on the interstellar medium directed away from the Galactic disc. If this force is larger than the gravitational pull due to the mass embedded in the Galaxy, then galactic winds may be launched. Such outflows may have important implications for the history of star formation of the host galaxy, and in turn affect in a crucial way the transport of cosmic rays, both due to advection with the wind and to the excitation of waves by the same cosmic rays, through streaming instability. The possibility to launch cosmic ray induced winds and the properties of such winds depend on environmental conditions, such as the density and temperature of the plasma at the base of the wind and the gravitational potential, especially the one contributed by the dark matter halo. In this paper we make a critical assessment of the possibility to launch cosmic ray induced winds for a Milky-Way-like galaxy and how the properties of the wind depend upon the conditions at the base of the wind. Special attention is devoted to the implications of different conditions for wind launching on the spectrum of cosmic rays observed at different locations in the disc of the galaxy. We also comment on how cosmic ray induced winds compare with recent observations of Oxygen absorption lines in quasar spectra and emission lines from blank-sky, as measured by XMM-Newton/EPIC-MOS. Speaker: Sarah Recchia • 4:00 PM 6:00 PM Cosmology Spartan Room (The Athenaeum) ### Spartan Room #### The Athenaeum Convener: Dragan Huterer (University of Michigan) • 4:00 PM Cosmology with the HETDEX survey 30m HETDEX (Hobby-Eberly Telescope Dark Energy eXperiment) is a galaxy survey targeting Lyman-alpha emitters (LAEs) at high redshifts (1.9<z<3.5). Starting from late 2017, the survey will observe about a million LAEs over ~400 sq. degrees, which corresponds to ~10Gpc^3 in volume. The main science goal of HETDEX is to measure the angular diameter distance and the Hubble expansion rate at high redshifts (z~2.5 and z~3) within a percent accuracy, so that we can measure the dark energy density better than 3-sigma. In this talk, I will introduce the HETDEX survey, summarize the survey design, observing strategy, as well as some result from the commissioning data. Speaker: Dr Donghui Jeong (The Pennsylvania State University) • 4:30 PM CMB Foregrounds: Problems, Parameterizations, and Progress 15m The next frontiers in cosmic microwave background (CMB) science include a detailed mapping of the CMB polarization field, with goals of detecting the inflationary B-mode signal and constructing high-fidelity maps of the matter distribution via CMB lensing reconstruction, as well as a first detection of CMB spectral distortions. At these levels of precision (~nK), Galactic and extragalactic foregrounds may be the ultimate limiting factor in deriving cosmological constraints. In this context, I will discuss recent work focused on extending CMB foreground parameterizations in a systematic, flexible way, with applications to both polarization and spectral distortion measurements. I will apply this methodology to spectral distortion detection forecasts for the Primordial Inflation Explorer, showing that high-significance measurements of the Compton-y and relativistic thermal Sunyaev-Zel’dovich signals can be expected. I will conclude with a discussion of foregrounds in CMB lensing measurements, focusing on the kinematic Sunyaev-Zel’dovich effect, as well as recent progress in B-mode delensing, in which the CMB lensing signal itself represents a foreground for inflationary B-mode constraints. Speaker: James Colin Hill (Columbia University) • 4:45 PM CMB Polarization B-mode Delensing with SPTpol and Herschel 15m Inflation generically predicts a background of primordial gravitational waves, which generate a primordial B-mode component in the polarization of the cosmic microwave background (CMB). The measurement of such a B-mode signature would lend significant support to the paradigm of inflation and be important for development of quantum gravity theories. Observed B modes also contain a component from the gravitational lensing of primordial E modes, which can obscure the measurement of the primordial B modes. If the amplitude of primordial B modes is sufficiently small, the lensing component will need to be cleaned using a process called ‘delensing.’ Delensing has been studied theoretically and with simulations but has not been demonstrated with data until recently. I will present delensing of a measurement of the CMB B-mode power spectrum from SPTpol using data from Herschel as a tracer of the lensing potential. The measured B-mode power is reduced by 28 percent on sub-degree scales, in agreement with predictions from simulations, and the null hypothesis of no delensing is ruled out at 6.9 sigma. Furthermore, we develop and use a suite of realistic simulations to investigate and validate the delensing process. This work represents a crucial step on the road to detecting primordial gravitational waves. Speaker: W.L. Kimmy Wu (UC Berkeley) • 5:00 PM Cosmology with the Lyman-alpha Forest 15m The Lyman-alpha forest provides a powerful probe of cosmic structure at z = 2-4, with physics that is relatively straightforward. I will discuss current constraints on dark energy from baryon acoustic oscillation measurements in the 3-d Lya forest and on neutrino masses from the 1-d Lya forest power spectrum, with measurements coming from the Baryon Oscillation Spectrosopic Survey (BOSS). I will discuss prospects and challenges ahead, with emphasis on accurate modeling and anticipated measurements from DESI. Speaker: Prof. David Weinberg (Ohio State University) • 5:15 PM Cosmological Results from BOSS and eBOSS 15m I will present results from the completed Sloan Digital Sky Survey (SDSS)-III Baryon Oscillation Spectroscopic Survey (BOSS) and initial results from the SDSS-IV extended BOSS (eBOSS). These experiments have obtained spectroscopic redshifts for nearly 2 million galaxies and quasars, allowing the creation of 3 dimensional maps spanning most of the history of the Universe. In addition to other key science results, I will explain how the baryon acoustic oscillation (BAO) feature can be located in these maps and used as a "standard ruler" to allow distance measurements and powerful tests of dark energy. Speaker: Ashley Ross (Ohio State University) • 5:30 PM Emulating galaxy clustering and galaxy-galaxy lensing into the deeply nonlinear regime 15m We model galaxy-galaxy lensing and clustering into nonlinear scales with a suite of N-body simulations, and we project significantly tighter cosmological parameter constraints possible within the ΛCDM parameter space and a HOD galaxy biasing model by using small scales. To include possible assembly bias effects, we introduce a two-halo environmental density dependence parameter into our model and show that fully-marginalized cosmological constraints should improve by greater than a factor of two using scales$0.5 < r_p < 30$Mpc h$^{−1}$compared to using only scales > 5 Mpc h$^{−1}$. We forecast that combining clustering information from the BOSS LOWZ sample and galaxy-galaxy lensing from SDSS imaging can constrain the combined cosmological parameter$\sigma_8 \Omega_M^{0.3}to 2.4 per cent, and full-depth DES imaging may improve this constraint to 1 per cent (assuming 10 galaxies per square arcminute). Speaker: Ben Wibking (Ohio State University) • 5:45 PM Extremely Efficient Cosmological Perturbation Theory with FAST-PT 15m Cosmological perturbation theory is a powerful tool to model observations of large-scale structure in the weakly non-linear regime. However, even at next-to-leading order, it results in computationally expensive mode-coupling integrals. In this talk, I will focus on the physics of our extremely efficient algorithm, FAST-PT. I will show how the algorithm can be applied to calculate 1-loop power spectra for several cosmological observables, including the matter density, galaxy bias, galaxy intrinsic alignments, the Ostriker-Vishniac effect, the secondary CMB polarization due to baryon flows, and redshift-space distortions. Our public code is written in Python and is easy to use and adapt to additional applications. Speaker: Xiao Fang (The Ohio State University) • 4:00 PM 6:00 PM Dark matter Small Theater (The Athenaeum) ### Small Theater #### The Athenaeum Convener: C Eric Dahl (Northwestern University) • 4:00 PM Measurement of low energy ionization signals from Compton scattering in a CCD dark matter detector 15m An important source of background in direct searches for low-mass dark matter particles are the energy deposits by small-angle scattering of environmental γ rays. We report detailed measurements of low-energy spectra from Compton scattering of γ rays in the bulk silicon of a charge-coupled device (CCD). Electron recoils produced by γ rays from 57Co and 241Am radioactive sources are measured between 60 eV and 4 keV. The observed spectra agree qualitatively with theoretical predictions, and characteristic spectral features associated with the atomic structure of the silicon target are accurately measured for the first time. A theoretically-motivated parametrization of the data that describes the Compton spectrum at low energies for any incident γ-ray flux is derived. The result is directly applicable to background estimations for low-mass dark matter direct-detection experiments based on silicon detectors, in particular for the DAMIC experiment down to its current energy threshold. Speaker: Karthik Ramanathan (University of Chicago) • 4:15 PM The LDMX Experiment 15m The Light Dark Matter eXperiment (LDMX) proposes a high-statistics search for low- mass dark matter at a new experimental facility, Dark Sector Experiments at LCLS-II (DASEL), at SLAC. LDMX employs the missing momentum technique, where electrons scattering in a thin target can produce dark matter via “dark bremsstrahlung” that are not observed in the detector. To identify these rare signal events, LDMX individually tags incoming beam-energy electrons, unambiguously associates them with low energy, moderate transverse-momentum recoils of the incoming electron, and establishes the absence of any ad- ditional forward-recoiling charged particles or neutral hadrons. LDMX will employ low mass tracking to tag incoming beam-energy electrons with high purity and cleanly reconstruct recoils. A high-speed, granular calorimeter with MIP sensitivity is used to reject the high rate of bremsstrahlung background at trigger level while working in tandem with a hadronic calorimeter to veto rare photo nuclear reactions. Ultimately, LDMX aims to probe thermal dark matter over most of the viable sub-GeV mass range to a decisive level of sensitivity. This talk will summarize the current status of the LDMX design and performance studies and progress in developing the DASEL beamline. Speaker: Joshua Hiltbrand (University of Minnesota (US)) • 4:30 PM The DAMIC experiment at SNOLAB 15m Charge-coupled devices (CCDs) are excellent particle detectors with the ability to probe a wide range of low-mass dark matter candidates. Initially developed for use in astronomy, CCDs have low per-pixel noise and excellent spatial resolution, giving them unique background discrimination and low (<100eV) energy thresholds. I will present the status of the DAMIC100 experiment, an ongoing direct dark matter search consisting of an array of 16 megapixel CCDs operated in the low radioactivity environment of the SNOLAB underground laboratory. Speaker: Ryan Thomas (University of Chicago) • 4:45 PM Recent Results and Current Status of SuperCDMS 15m SuperCDMS (Cryogenic Dark Matter Search) has been one of the leading direct dark matter search experiments using low-temperature semiconductor detectors. The recoil energy induced by dark matter scattering inside the detector is measured using phonon (lattice vibration) and ionization signals. CDMSlite (low-ionization threshold experiment) within SuperCDMS Soudan has the best dark matter-nucleon scattering cross section limits in the world for low-mass dark matter particles with masses between 2-5GeV/c2. With unique discovery potential for low-mass dark matter and complementary to higher-mass dark matter searches with other experiments, SuperCDMS plays a vital role in the search for dark matter. We are now moving forward with SuperCDMS SNOLAB, a DOE/NSF/CFI funded direct detection dark matter search experiment. In this talk, I will present the recent results from SuperCDMS Soudan as well as an overview and the current status of SuperCDMS SNOLAB. Speaker: Dr Tsuguo Aramaki (SLAC) • 5:00 PM MiniBooNE Dark Matter Search 15m The MiniBooNE experiment at Fermilab performed the first dedicated search for accelerator proton beam produced dark matter. By steering the 8 GeV beam into an iron beam dump, the neutrino production from charged meson decay was suppressed while the photon production from neutral mesons remained unchanged. According to hidden-sector vector portal models, the Standard Model photons kinetically mix with dark photons that decay into dark matter and travel towards the MiniBooNE detector. The experiment looked for dark matter particles scattering elastically off of nucleons in the detector medium and set new limits for the existence of sub-GeV dark matter within a vector portal model. In this talk, the experimental setup, analysis methods and ongoing analyses will be discussed. The results from MiniBooNE show that Fermilab could be at the forefront of searches for sub-GeV dark matter. Speaker: Ranjan Dharmapalan (Argonne National Laboratory) • 5:15 PM Scintillating Bubble Chamber for Dark Matter and CEνNS Detection 15m Scintillating bubble chambers are demonstrated to have clean separation between electron recoils and nuclear recoils down to a thermodynamic “Seitz” threshold of 2 keV with a prototype liquid xenon chamber developed at Northwestern University, as the former only produce scintillation light while the later produce both scintillation light and bubble nucleation. This clean separation is expected to extend down to the thermal stability limit of the target fluid, enabling the realization of WIMP or CEvNS detectors with sub-keV threshold. The demonstrated behavior for liquid xenon is expected to hold for other noble liquids such as argon, which expands the physics reach of the new technology. The prototype chamber is instrumented with a CCD camera for near-IR bubble imaging, a solar-blind PMT to detect 175-nm xenon scintillation light, and piezoelectric acoustic transducers to detect the ultrasonic emission from a growing bubble. Speaker: Jianjie Zhang (Northwestern University) • 5:30 PM Recent results from the MAJORANA DEMONSTRATOR 15m The MAJORANA DEMONSTRATOR is an experiment constructed to search for neutrinoless double-beta decays in germanium-76 and to demonstrate the feasibility to deploy a large-scale experiment in a phased and modular fashion. It consists of two modular arrays of natural and 76Ge-enriched germanium detectors totalling 44.1 kg, located at the 4850' level of the Sanford Underground Research Facility in Lead, South Dakota, USA. While crucial for its neutrinoless double-beta decay search, the ultra-low backgrounds and excellent energy resolution of the MAJORANA DEMONSTRATOR also allow it to probe additional physics beyond the Standard Model. This includes searches for dark matter and solar axions. This talk will discuss the results to date from the neutrinoless double-beta decay and beyond the Standard Model searches, as well as the future prospects of the MAJORANA DEMONSTRATOR. Speaker: Dr Jordan Myslik (Lawrence Berkeley National Laboratory) • 5:45 PM Free 15m • 4:00 PM 6:00 PM Dark matter Athenian Room (The Athenaeum) ### Athenian Room #### The Athenaeum Convener: dan hooper • 4:00 PM Flavoured Dark Matter in Dark Minimal Flavour Violation 15m We study simplified models of flavoured dark matter in the framework of Dark Minimal Flavour Violation. In this setup the coupling of the dark matter flavour triplet to SM quark triplets constitutes the only new source of flavour and CP violation. The parameter space of the model is restricted by LHC searches with missing energy final states, by neutral meson mixing data, by the observed dark matter relic abundance, and by the absence of signal in direct detection experiments. We consider all of these constraints in turn, studying their implications for the allowed parameter space. Especially interesting is the combination of all constraints, reveling a non-trivial interplay. Large parts of the parameter space are excluded, most significantly in light of future bounds from upcoming experiments. Speaker: Simon Kast (Karlsruhe Institute for Technology) • 4:15 PM Enhancing Dark Matter Annihilation Rates with Dark Bremsstrahlung 15m Many dark matter interaction types lead to annihilation processes which suffer fromp$-wave suppression or helicity suppression, rendering them sub-dominant to unsuppressed$s$-wave processes. We demonstrate that the natural inclusion of dark initial state radiation can open an unsuppressed$s$-wave annihilation channel, and thus provide the dominant dark matter annihilation process for particular interaction types. We illustrate this effect with the bremsstrahlung of a dark pseudoscalar or vector boson from fermionic dark matter,$\overline{\chi}\chi\rightarrow \overline{f}f\phi$or$\overline{f}fZ'$. The dark initial state radiation process, despite having a 3-body final state, proceeds at the same order in the new physics scale$\Lambda$as the annihilation to the 2-body final state$\overline{\chi}\chi\rightarrow \overline{f}f$. This is lower order in$\Lambda$than the well-studied lifting of helicity suppression via Standard Model final state radiation, or virtual internal bremsstrahlung. This dark bremsstrahlung process should influence LHC and indirect detection searches for dark matter. Speaker: Nicole Bell (University of Melbourne) • 4:30 PM Dark Forces in the Sky: Signals from Z' and the Dark Higgs 15m We consider the indirect detection signals for models containing a fermionic DM candidate, a dark gauge boson, and a dark Higgs field. Compared with a model containing only a dark matter candidate and vector mediator, the addition of the scalar provides a mass generation mechanism for the dark sector particles which, in some cases, is required in order to avoid unitarity violation at high energies. We demonstrate that the dark matter interaction types, and hence the annihilation processes relevant for relic density and indirect detection, are strongly dictated by the mass generation mechanism chosen for the dark sector particles, and the requirement of gauge invariance. We outline important phenomenology of such two-mediator models, which is missed in the usual single-mediator simplified model approach. In particular, the inclusion of the two mediators opens up a new, dominant, s-wave annihilation channel that does not arise when a single mediator is considered in isolation. Speaker: Nicole Bell (University of Melbourne) • 4:45 PM Dark Matter Models for the Galactic Center Excess 15m The origin of the Galactic Center Gamma-Ray excess still remains unclear. Astrophysical interpretations have been proposed, but these explanations require either a significant degree of tuning or a large population of millisecond pulsars that have a very different population than that observed in globular clusters or near the Milky Way. If the dark matter annihilation interpretation is assumed, one should expect additional signatures at colliders and at direct detection experiments. In this talk I will present the current constraints on dark matter models that are able to successfully explain the Galactic Center excess. Speaker: Miguel Escudero (IFIC-University of Valencia) • 5:00 PM Sharp spectral features from light dark matter decay via gravity portals 15m So far, all evidence for the existence of dark matter is based on its gravitational interactions with the observable sector, and its precise particle nature remains mysterious. However, even if dark matter is stable against decay in flat spacetime, as commonly assumed in the literature, the presence of nonminimal couplings to gravity of the dark matter field can spoil this stability in curved spacetime, with potentially remarkable phenomenological implications. More specifically, a scalar dark matter candidate with a mass in the MeV-GeV region, destabilized through a linear coupling to the Ricci scalar, can decay into electron-positron pairs and photons. This has implications for both the thermal history of the Universe and the present-day gamma-ray spectrum observed at Earth. Observations of the cosmic microwave background by the Planck satellite and of the extragalactic isotropic gamma-ray background by COMPTEL, EGRET and Fermi LAT can be used to constrain the size of the nonminimal coupling parameter. Speaker: Sebastian Ingenhütt • 5:15 PM Cooling sterile neutrino dark matter 15m Sterile neutrinos produced through resonant or non-resonant oscillations are a well motivated dark matter candidate, but recent constraints from observations have ruled out most of the parameter space. Based on general considerations we find a thermalization mechanism which can increase the yield after resonant and non-resonant production. At the same time, it alleviates the growing tensions with structure formation and X-ray observations and even revives simple non-resonant production as a viable way to produce sterile neutrino dark matter. We investigate the parameters required for the realization of the thermalization mechanism in a representative model and find that a simple estimate based on energy- and entropy conservation describes the mechanism well. Speaker: Dr Stefan Vogl • 5:30 PM Phase Method for the evaluation of Sommerfeld Enhancement 15m In this talk, I will present the application of Calogero's Variable Phase method for the determination of Sommerfeld Enhancement factors relevant for dark matter cross section calculations. In contrast to directly solving the radial Schrodinger equation, the evaluation using the Variable Phase Method offers a rapid and stable evaluation, even for multichannel systems. Time permitting, I will outline strategies for obtaining new analytic results by looking for asymptotic approximations to the variable phase equations. Speaker: Dr Hiren Patel (UMass Amherst) • 5:45 PM Au Genesis From Cogenesis: Heavy Asymmetric Dark Matter Makes Gold 15m The early universe could feature multiple reheating events, leading to jumps in the visible sector entropy density that dilute both particle asymmetries and the number density of frozen-out states. In fact, late time entropy jumps are usually required in models of Affleck-Dine baryogenesis, which typically produces an initial particle-antiparticle asymmetry that is much too large. An important consequence of late time dilution, is that a smaller dark matter annihilation cross section is needed to obtain the observed dark matter relic density. For cosmologies with high scale baryogenesis, followed by radiation-dominated dark matter freeze-out, the perturbative unitarity mass bound on thermal relic dark matter is relaxed to thousands of PeV. An extensive direct detection search program is necessary to uncover such dark matter. Intriguingly, within the dilute thermal relic framework, PeV mass asymmetric dark matter could be responsible for the production of heavy r-process elements, including gold. Speaker: Joseph Andrew Bramante • 4:00 PM 6:00 PM Galactic sources Corinthian Room (The Athenaeum) ### Corinthian Room #### The Athenaeum Convener: Patrick Slane (Harvard-Smithsonian Center for Astrophysics) • 4:00 PM Supernova Remnant Studies with Fermi LAT 30m Supernova remnants (SNRs) have been studied at GeV energies using the Fermi Large Area Telescope (LAT) for nearly a decade. The detection of the pion bump in four SNRs demonstrates that these are sources of cosmic ray protons. However, the detailed physics of particle acceleration (or re-acceleration) and diffusion remain undetermined. To determine the Galactic cosmic ray contribution from SNRs requires both a larger gamma-ray sample of Galactic SNRs and detailed spectral and spatial studies at GeV and TeV energies. Recently released Pass 8 data significantly improves the sensitivity and angular resolution of GeV studies of SNRs. A complete search for extended sources located along the Galactic plane at energies above 10 GeV has detected 46 extended sources, 16 of which are newly identified and likely to be either SNRs or pulsar wind nebulae. Joint studies with observatories at TeV energies — HAWC, MAGIC and VERITAS - characterize spectra of 16 new unassociated HAWC sources at TeV energies and spatially resolve shock-cloud interaction regions of the well-studied SNR IC 443. Such multi-instrument studies promise to uncover the origins of SNRs as cosmic accelerators. Speaker: John Hewitt (University of North Florida) • 4:30 PM Multi-year observations of the Galactic Center region with the MAGIC telescopes 15m The Galactic Center region is one of the primary targets for observations with the current generation of gamma-ray telescopes. This attention is primarily caused by the presence of a black hole of 4 million solar masses, which provides a rare opportunity to study the interaction of a super-massive black hole with surrounding matter at a relatively close distance. Recently the interest to this region was increased by a series of exciting discoveries: the large, extended bubbles detected with Fermi/LAT, the envisioned burst of high-energy emission due to the passage of the G2 gas cloud, the likely pevatron nature of the primary source unveiled with H.E.S.S. and the discovery of a new source in the region, reported by the major Cherenkov telescopes MAGIC, H.E.S.S. and VERITAS. All these underline the complex physics of the region, revealed by deep gamma-ray observations. In this talk I will present the results of the multi-year observational program of the Galactic Center region with the MAGIC telescopes, conducted at large zenith angle. I will discuss in detail the morphology of this region and compare it with predictions of several different models. Speaker: Ievgen Vovk • 4:45 PM Evidence Against a Dark Matter Explanation of the Galactic Center Excess 15m An anomalous, apparently diffuse, gamma-ray signal not readily attributable to known Galactic sources has been found in Fermi space telescope data covering the central ~10 degrees of the Galaxy. This "Galactic Center Gamma-Ray Excess" (GCE) signal has a spectral peak at ~2 GeV and reaches its maximum intensity at the Galactic Centre (GC) from where it falls off as a radial power law ~r^{-2.4}. Given its morphological and spectral characteristics, the GCE is ascribable to self-annihilation of dark matter particles governed by an Navarro-Frenk-White-like density profile. However, it could also be composed of many dim, unresolved point sources for which millisecond pulsars (MSPs) or pulsars would be natural candidates given their GeV-peaked spectra. Statistical evidence that many sub-threshold point sources contribute up to 100% of the GCE signal has recently been claimed. We have developed a novel analysis that exploits hydrodynamical modelling to better register the position of gamma-ray emitting gas in the Inner Galaxy. Our improved analysis reveals that the excess gamma-rays are spatially correlated with both the X-shaped stellar over-density in the Galactic bulge and the nuclear stellar bulge. Given these correlations, we argue that the excess is not a dark matter phenomenon but rather associated with the stellar population of the X-shaped bulge and the nuclear bulge. Speaker: Oscar Macias (Virginia Tech) • 5:00 PM Characterizing the population of pulsars in the Galactic bulge with the Fermi Large Area Telescope 15m Several groups have demonstrated the existence of an excess in the gamma-ray emission around the Galactic Center (GC) with respect to the predictions from a variety of Galactic Interstellar Emission Models (GIEMs) and point source catalogs. The origin of this excess, peaked at a few GeV, is still under debate. A possible interpretation is that it comes from a population of unresolved Millisecond Pulsars (MSPs) in the Galactic bulge. We investigate the detection of point sources in the GC region using new tools which the Fermi-LAT Collaboration is developing in the context of searches for Dark Matter (DM) signals. These new tools perform very fast scans iteratively testing for additional point sources at each of the pixels of the region of interest. We show also how to discriminate between point sources and structural residuals from the GIEM. We apply these methods to the GC region considering different GIEMs and testing the DM and MSPs intepretations for the GC excess. Our analysis is capable of finding the characteristics of this putative population of MSPs in the Galactic bulge of our Galaxy. Additionally, we create a list of promising MSP candidates that could represent the brightest sources of a MSP bulge population. Speaker: mattia di mauro (Stanford University) • 5:15 PM The Galactic-Center excess and 511 keV Bulge emission: two sides of the same coin? 15m A clear excess at ~2 GeV, known as the Galactic-Center Excess (GCE), has been detected in the Galactic Bulge region by the Fermi telescope. In addition, the Galactic Bulge is characterised by the annihilation of positrons resulting in a 511 keV line. Both signals look morphologically similar, but so far a detailed comparison has been lacking from the literature. We model the GCE using the new gamma-ray modelling code SkyFact and compare the results to spatial models of the 511 keV excess. We find that the GCE and 511 keV excess are compatible with identical source distributions and speculate about potential common origins in terms of population synthesis. In addition, we discuss future directions that can potentially test whether the GCE and 511 keV signal are connected. Speaker: Richard Bartels (University of Amsterdam) • 5:30 PM Free 15m • 5:45 PM Free 15m Free • 6:30 PM 8:30 PM Conference reception OSU Physics Research Building #### OSU Physics Research Building 191 W. Woodruff Ave. • Tuesday, August 8 • 9:00 AM 12:00 PM Plenary session Davidson Theatre #### Davidson Theatre Convener: Mauricio Bustamante (Ohio State University) • 9:00 AM Neutrinos in the Era of Multimessenger Astronomy 30m We will review the status of the observations of cosmic neutrinos and the model-independent constraints on the properties of the sources where they originate. We will emphasize the multimessenger relations connecting neutrino, gamma ray, and cosmic-ray observations and conclude that neutrinos are ubiquitous in the nonthermal universe suggesting a more significant role than previously anticipated. We will discuss the prospect of observing individual point sources, as well as the “guaranteed” flux of cosmogenic neutrinos. Speaker: Francis Halzen (University of Wisconsin) • 9:30 AM Radio Detection of the Highest Energy Neutrinos 30m Searches for ultra-high energy neutrinos ($E>10^{17}$eV) probe the nature of the highest energy universe in a unique way and test our understanding of particle physics at energies much greater than those achievable at particle colliders. I will discuss the range of strategies used to search for the highest energy neutrinos via radio emission from neutrino-induced showers, and the current status of measurements. The future of high energy neutrino detection lies with ground-based radio arrays, which would represent an enormous leap in sensitivity and may be able to push the energy threshold for radio detection down to overlap with the energy range probed by IceCube. Speaker: Abigail Vieregg (University of Chicago) • 10:00 AM Coffee break 30m • 10:30 AM Neutrino Astronomy - Fast Forward 30m I will review some of the open questions in high-energy neutrino astronomy raised by the observations of IceCube in concert with cosmic ray and gamma-ray observatories, and how they can be addressed through a new generation of neutirno observatories. Speaker: Mr Marek Kowalski (HU Berlin and DESY) • 11:00 AM Very high-energy emission from transients 30m I briefly review the status of high-energy emission from astronomical transients concentrating on current efforts to detect high-energy emission from strongly interacting shocks of young stellar explosions (both ordinary and superluminous). In particular, I will present the case of the search for high-energy emission from the remarkable SN2014C. SN2014C evolved from a normal Type I core-collapse SN into a strongly interacting SN of Type II, violating the traditional classification scheme of type I vs. type II stellar explosions. Speaker: Raffaella Margutti • 11:30 AM Connections to Compact Dark Matter 30m The elusive nature of dark matter calls for new ideas. An old but largely overlooked possibility is compact dark matter—perhaps primordial black holes—with masses comparable to the masses of stars. Null microlensing searches rule out fairly robustly masses below ten solar masses. Constraints to higher masses are, however, a bit trickier but have been the subject of considerable recent study. I will review the motivation for this exploration, current constraints (and their uncertainties), and some possible future probes. The work discussed makes connections with gravitational-wave astrophysics, high-energy astrophysics, stellar dynamics, the cosmic microwave background, and cosmology at much earlier and much later times. Speaker: Prof. Marc Kamionkowski (Johns Hopkins University) • 12:00 PM 2:00 PM Lunch 2h • 2:00 PM 3:30 PM Cosmology Spartan Room (The Athenaeum) ### Spartan Room #### The Athenaeum Convener: Dragan Huterer (University of Michigan) • 2:00 PM Massive neutrinos in cosmology 30m Cosmological observations represent a powerful tool to constrain neutrino physics, complementary to laboratory experiments. In particular, observations of the cosmic microwave background (CMB) have the potential to constrain the properties of relic neutrinos, as well as of additional light relic particles in the Universe. I will present current constraints on neutrino properties, focusing on their mass and effective number, from the most recent Planck data, possibly in combination with other cosmological probes, especially galaxy surveys. I will also discuss prospects from future experiments, both from the ground and from space. Speaker: Massimiliano Lattanzi (Istituto Nazionale di Fisica Nucleare) • 2:30 PM Interacting neutrinos in cosmology: exact description and constraints 15m We study and constrain the impact of non-standard neutrino interactions on the CMB angular power spectrum. Starting from the collisional Boltzmann equation, we derive the Boltzmann hierarchy for neutrinos including interactions with a massive scalar particle. In contrast to the Boltzmann hierarchy for photons, our interacting neutrino Boltzmann hierarchy is momentum dependent, which reflects non-negligible energy transfer in the considered neutrino interactions. We implement this Boltzmann hierarchy into the Boltzmann solver CLASS and compare our results with known approximations in the literature. We thereby find a very good agreement between our exact approach and the relaxation time approximation (RTA). The popular$\left( c_{\text{eff}}^2,c_{\text{vis}}^2 \right)$-parametrization however does not reproduce the correct signal in the CMB angular power spectrum. Using the RTA, we furthermore derive constraints on the effective coupling constant$G_{\text{eff}}$from currently available cosmological data. Our results reveal a bimodal posterior distribution, where one mode represents the standard$\Lambda$CDM limit, and the other a scenario of neutrinos self-interacting with$G_{\rm eff} \simeq 3 \times 10^9 \, G_{\rm F}$(where$G_{\text{F}}$is the Fermi coupling). Speaker: Isabel M. Oldengott (Bielefeld University) • 2:45 PM Constraints on secret interactions among sterile neutrinos from Planck 2015 data 15m Light sterile neutrinos with eV mass have been suggested by different anomalies observed in short-baseline neutrino experiments. These particles would have been produced in the Early Universe changing the amount of relativistic energy density by increasing the effective number of relativistic species ($N_{\rm{eff}}$). This results in a conflict with existing cosmological bounds on primordial radiation density and neutrino mass. In order to alleviate these discrepancies, basically avoiding the thermalization of eV sterile neutrinos in the early Universe, secret interactions in the sterile sector mediated by a massive vector boson ($M_X < M_W$) have been proposed. Secret interactions reduce the effective mixing angle generating a large matter potential in the sterile neutrino sector and suppressing the active-sterile oscillations. In particular if the interactions are mediated by a gauge boson having$M_X < 10$MeV, the sterile neutrino productions is suppressed for$T > 0.1$eV; this behaviour seems to ameliorate the conflict between the cosmological constraints and laboratory experiments. Observations of the cosmic microwave background (CMB) radiation represent a powerful and unique tool to test this model in more detail. During my presentation I will show results of a dedicated study presenting constraints on the strength of the secret interaction and the corresponding mass bounds using the latest CMB Planck 2015 data. Finally I will discuss the status of the sterile neutrino secret interaction scenario after this work. Speaker: Francesco Forastieri (University of Ferrara) • 3:00 PM Neutrinos with CMB and CMB lensing 15m A number of ground-based CMB surveys are currently in the planning stages that will provide significant new information on properties of physics beyond the standard model. Measurements of the lensing of the CMB are expected to provide evidence for neutrino mass in the case of a minimal mass as expected from neutrino oscillation experiments. Meanwhile measurements of the phase of the acoustic plasma will provide constraints on particles that are in equilibrium with the standard model prior to decoupling. After reviewing the prospects for these measurements I will discuss some of the technical challenges involved. Speaker: Dr Alexander van Engelen • 3:15 PM Cosmological searches for a non-cold dark matter component 15m The standard$\Lambda$CDM cosmological model has successfully explained large scale cosmological observations. However, there are some discrepancies between the$\Lambda$CDM predictions and measurements at small scales. Even though these discrepancies could be due to unaccounted effects on weak lensing analyses and/or numerical simulations, in this talk, I will explore the possibility of extending the standard cosmological model with an additional, subdominant, non-cold dark matter component. In particular, I will show the impact of such a scenario on various cosmological probes, including the CMB (Planck), weak lensing surveys measurements (KIDS) and the number of satellite galaxies in the Milky Way. Speaker: Miguel Escudero (IFIC-University of Valencia) • 2:00 PM 3:30 PM Dark matter Small Theater (The Athenaeum) ### Small Theater #### The Athenaeum Convener: Francesca Calore (LAPTh, CNRS) • 2:00 PM Testing Cold Dark Matter with Strong Gravitational Lensing of AGN 15m Strong gravitational lensing provides a means of measuring the halo mass function into regimes below which baryons are reliable tracers of structure. In this low mass regime (M_vir<10^9 M_sun), the microscopic characteristics of dark matter affect the predicted abundance of dark matter halos. Strong gravitational lensing has been limited by the small number of systems which can be used to detect dark matter substructure. I will discuss the narrow-line lensing technique, which enables a significant increase in the number of systems which can be used to measure the subhalo mass function, and the projected constraint on Cold vs. Warm Dark Matter with just the current sample of known strong gravitational lenses. Speaker: Anna Nierenberg • 2:15 PM Searching for dark disks using Gaia 15m Astrometry in the Gaia era will give an unprecedented amount of information about the full 6D phase space distribution of the local galactic halo. In this talk, I will use an analysis of vertical motions to show how the Gaia data will be sensitive to the presence of structures including dark disks (either from novel dark matter microphysics or from baryonic dragging.) Speaker: KATELIN SCHUTZ (UC Berkeley) • 2:30 PM Dwarf Galaxy Population of a Nearby Star-Forming Galaxy and Implications for Dark Matter 15m We present our first results from a deep LBT survey of dwarf satellites of nearby star-forming galaxies outside the local group. We present our candidates and report the number and distribution of satellites for our first system. We are sensitive to deep within the ultra faint dwarf and ultra diffuse galaxy regime outside. We discuss the implications of these new observations on the dark matter halo distribution function and dark matter models. Speaker: Alexandra Davis (Ohio State University) • 2:45 PM Searching for ultra-faint galaxies in three years of data from the Dark Energy Survey 15m Deep optical imaging surveys have revealed a population of extremely low luminosity and dark matter dominated galaxies orbiting the Milky Way. The total number of Milky Way satellite galaxies and the demographics of this population are still largely unknown, in part, because of complex selection effects that limit our ability to detect the lowest surface brightness galaxies. The Dark Energy Survey (DES) has now finished a complete reprocessing of data from the first three observing seasons, yielding a dataset with substantially improved depth, homogeneity, and photometric precision. We will describe progress towards a more robust statistical search for Milky Way satellite galaxies in DES data with the ultimate goal of constraining the luminosity function of the faintest galaxies as a test of galaxy formation and dark matter physics. Speaker: Keith Bechtol (LSST) • 3:00 PM Black Mergers, Quiet Kilonovae, and r-Process Afterglow Donuts From Dark Matter 15m We identify new astrophysical signatures of NS-imploding DM, which could decisively test these hypotheses in the next few years. First, NS-imploding DM forms ≪10−10 solar mass black holes inside NSs, thereby converting NSs into ∼1.5 solar mass BHs. This decreases the number of NS mergers seen by LIGO/VIRGO (LV) and associated merger kilonovae seen by telescopes like DES, BlackGEM, and ZTF, instead producing a population of "black mergers" containing ∼1.5 solar mass black holes. Second, DM-induced NS implosions create a new kind of kilonovae that lacks a detectable, accompanying gravitational signal. Using DES data and the Milky Way's r-process abundance, we set bounds on these DM-initiated "quiet-kilonovae." Third, the spatial distribution of merger kilonovae, quiet kilonovae, and fast radio bursts in galaxies can be used to detect dark matter. NS-imploding DM destroys most NSs at the centers of mature disc galaxies, so that NS merger kilonovae would appear mostly in a donut at large radii. We find that as few as ten NS merger kilonova events, located to ∼1 kpc precision could validate or exclude DM-induced NS implosions at 2σ confidence, exploring DM-nucleon cross-sections over an order of magnitude below current limits. Similarly, NS-imploding dark matter as the source of fast radio bursts can be tested at 2σ confidence once 20 bursts are located in host galaxies by radio arrays like CHIME and HIRAX. URL: https://arxiv.org/abs/1706.00001 I am also submitting an abstract to the track Particle Physics. Speaker: Yu-Dai Tsai (Cornell University) • 3:15 PM Dark Fires in the Sky: Model-Independent Dark Matter Detection via Kinetic Heating of Neutron Stars 15m A largely model-independent probe of dark matter-nucleon interactions is proposed. Accelerated by gravity to relativistic speeds, local dark matter scattering against old neutron stars deposits kinetic energy that heats them to infrared blackbody temperatures. The resulting radiation could be detected by next generation telescopes such as James Webb, the Thirty Meter Telescope and the European Extremely Large Telescope. While underground direct detection searches are not (or poorly) sensitive to dark matter with sub-GeV masses, higher-than-weak-scale masses, scattering below neutrino floors, spin-dependent scattering well below nuclear cross-sections, pseudoscalar-mediated scattering, and inelastic scattering for inter-state transitions exceeding O(100 keV), dark kinetic heating of neutron stars advances these frontiers by orders of magnitude, and should vastly complement these searches. Popular dark matter candidates previously suspected challenging to probe, such as thermal Higgsinos, may be discovered. Speaker: Nirmal Raj • 2:00 PM 3:30 PM Galactic sources Macedonian Room (The Athenaeum) ### Macedonian Room #### The Athenaeum Convener: Elena Orlando (Stanford University) • 2:00 PM Unexpectedly bright: high energy emission from mixed morphology SNRs 30m Supernova remnants (SNRs) are the long lived structures that result from the explosive end of a massive star. The expanding shock-front produced by the supernova explosion heats stellar ejecta and swept-up ISM to X-ray emitting temperatures, and are sites in which populations of relativistic particles can be efficiently accelerated to the knee of the Cosmic-ray spectrum. For SNRs that are born in regions of high density, the interaction between the SNR with this dense molecular material has a profound effect on the morphology and emission properties of these objects. Until recently, most studies have focused on individual sources, however, in this talk I will focus on the importance of systematically studying the properties of these objects. In particular, I will highlight current investigations into the high energy emission of these remnants using X-ray and gamma-ray satellites, and discuss the insights these studies have provided us with in regards to the properties of their progenitor, and their surrounding environment, as well as their ability to accelerate particles. Speaker: Katie Auchettl • 2:30 PM Complexities of a Mid-Life Crush: A Study of the Pulsar Wind Nebula Vela X 30m The Vela supernova remnant is a canonical example of a middle-aged composite system in which the SNR reverse shock has disrupted the central pulsar wind nebula, Vela X. Due to a non-uniform ambient medium, the shock has propagated asymmetrically, crushing the northern part of the PWN. The result is a complex structure characterized by nonthermal X-rays from the pulsar wind, thermal X-rays from ejecta mixed into the nebula, and gamma-ray emission in both the GeV and TeV bands, for which the morphology shows striking differences. Here we report on an XMM Large Project to study Vela X. We study variations in the spectral index of the nonthermal X-ray emission, along with the distribution and thermal properties of the shocked ejecta, and correlate these with the gamma-ray properties of the PWN. We evaluate these properties using hydrodynamical simulations in the context of the evolution of PWNe in composite SNRs, with a view to the ultimate fate of the relativistic particles produced in these systems. Speaker: Patrick Slane • 3:00 PM Studies of pulsar wind nebulae in TeV gamma-rays with H.E.S.S. 30m The survey of the Galactic plane in TeV gamma-rays by H.E.S.S. allows a systematic study of the population of pulsar wind nebulae (PWNe) in this energy domain. We find a mild trend of decreasing TeV luminosity with age, or decreasing spin-down power, as well as a trend of increasing size with age. Older TeV PWNe are generally displaced from the pulsar position, with offsets larger than can plausibly be explained by pulsar proper motion, which could be due to PWN interaction with the reverse shock in an asymmetric environment. The observed gamma-ray spectra can be ascribed to inverse Compton scattering of ambient photons, in which the Galactic far-infrared background often predominates; this may explain why luminous TeV PWNe are more readily detected in the inner spiral arms than in the outer Galaxy. We also present a more detailed morphological study of the TeV emission from the PWN in the composite supernova remnant MSH 15-52. We compare its gamma-ray morphology with that in synchrotron emission, obtained from archival X-ray observations, and discuss the implications for the magnetic field in the nebula. We also discuss potential extended gamma-ray emission beyond the X-ray PWN. Such an extended morphological component could come from electrons and positrons which have escaped the PWN, which would have implications for scenarios of PWNe as sources of leptonic cosmic rays. Speaker: Yves Gallant (LUPM, CNRS/IN2P3, U. de Montpellier) • 2:00 PM 3:30 PM Gamma rays Corinthian Room (The Athenaeum) ### Corinthian Room #### The Athenaeum Convener: Gareth Hughes (Smithsonian Center for Astrophysics) • 2:00 PM The Rise of the Leptons: Pulsar Emission Dominates the TeV Gamma-Ray Sky 15m Recent HAWC observations have found extended TeV emission coincident with the Geminga and Monogem pulsars. In this talk, I will show that these detections have significant implications for our understanding of pulsar emission. The isotropic nature of this emission provides a new avenue for detecting nearby pulsars with radio beams that are not oriented towards Earth. Additionally, I will show that the total emission from all unresolved pulsars produces the majority of the TeV gamma-ray flux observed from the Milky Way. Speaker: Tim Linden • 2:15 PM Are Starburst Galaxies Proton Calorimeters? 15m Several starburst galaxies have been observed in the GeV and TeV bands; in this regime, gamma-rays are mainly produced by cosmic-ray interactions with the interstellar medium ($p_{\rm cr}p_{\rm ism} \to \pi^{0} \to \gamma\gamma$). Furthermore, the dense environments of starbursts may act as proton "calorimeters" where collisions dominate losses, so that a substantial fraction of cosmic-ray energy input is emitted in gamma rays. Here we build a one-zone, "thick-target" model implementing calorimetry and placing a firm upper bound on gamma-ray emission from cosmic-ray interactions. The model assumes that cosmic rays are accelerated by supernovae, and all suffer nuclear interactions rather than escape. Our model has only two free parameters: the cosmic-ray proton acceleration energy per supernova$\epsilon_{\rm cr}$, and the proton injection spectral index$s$. We calculate the pionic gamma-ray emission from 10 MeV to 10 TeV, and derive thick-target parameters for six galaxies with Fermi, H.E.S.S., and/or VERITAS data. Our model provides good fits for the M82 and NGC 253, and yields$\epsilon_{\rm cr}$and$s$values suggesting that supernova cosmic-ray acceleration is similar in starbursts and in our Galaxy. We find that these starbursts are indeed nearly if not fully proton calorimeters. For NGC 4945 and NGC 1068, the models are consistent with calorimetry but are less well-constrained due to the lack of TeV data. However, the Circinus galaxy and the ultraluminous infrared galaxy Arp 220 exceed our pionic upper-limit; possible explanations will be discussed. Speaker: Xilu Wang (University of Illinois) • 2:30 PM The Multiwavelength Properties of Arp 220 15m When analyzed together, radio and gamma-ray observations make for a very powerful tool for studying and diagnosing extragalactic cosmic ray populations. The recent gamma-ray detection of the ultra-luminous galaxy Arp 220 is well above past predictions, indicating evidence of a very large cosmic ray population. Whether the star formation or an active galactic nucleus is the source of the additional cosmic, there is a clear excess of gamma-ray emission in comparison to the observed radio flux. Here, we analyze the amount of energy necessary to power the observed gamma-ray flux and compare with traditional tracers of the star-formation rate. We also explore possible mechanisms for lowering the corresponding radio flux and check for consistency with observed properties of the interstellar medium. Speaker: Dr Tova Yoast-Hull (Canadian Institute for Theoretical Astrophysics) • 2:45 PM A hadronic origin of the high-energy gamma rays from LMC 15m It has been suggested that high-energy gamma-ray emission ($>100MeV ) of nearby star-forming galaxies may be produced predominantly by cosmic rays colliding with the interstellar medium through neutral pion decay. The pion-decay mechanism predicts a unique spectral signature in the gamma-ray spectrum, characterized by a fast rising spectrum and a spectral break below a few hundreds of MeV. We here report the evidence of a spectral break around 500 MeV in the disk emission of Large Magellanic Cloud (LMC), which is found in the analysis of the gamma-ray data extending down to 60 MeV observed by {\it Fermi}-Large Area Telescope. The break is well consistent with the pion-decay model for the gamma-ray emission, although leptonic models, such as the electron bremsstrahlung emission, cannot be ruled out completely. Speaker: Dr Qingwen Tang (Nanchang University & CCAPP) • 3:00 PM Connecting Superluminous Supernovae, Gamma-ray Bursts, and Fast Radio Bursts to the Birth of Millisecond Magnetars 15m The repeating fast radio burst (FRB) 121102 was recently localized to a star-forming region in a dwarf host galaxy remarkably similar to those of superluminous supernovae (SLSNe) and long gamma-ray bursts (GRB), both of which were previously proposed to be powered by the birth of a millisecond magnetar. We demonstrate how a single magnetar engine can power both a SLSN and GRB, depending on the engine lifetime and the misalignment angle between the magnetar's rotation and magnetic axes. We also show that the production of a successful relativistic jet may be ubiquitous in engine-powered SLSNe, and describe several observational tests of this connection, including orphan radio afterglows and early optical signatures in the SLSN light curve. Finally, we describe recent results on the time-dependent ionization structure of the expanding supernova ejecta on timescales of decades following the explosion, due to photo-ionization by the nascent ‘magnetar wind nebula’. We precisely quantify when a fast radio burst can escape through the ejecta; create probability distributions of the local dispersion measure; and make predictions for the synchrotron radio emission from the magnetar wind nebula (analogous to the quiescent radio counterpart to FRB 121102). Speaker: Ben Margalit (Columbia University) • 3:15 PM RoboPol: Revealing the connection between gamma-ray activity in blazars and optopolarimetric rotations 15m Optical Synchrotron emission from blazars is significantly polarized and the polarization probes the magnetic field structure in the jet. Rotations of the polarization angle in blazars reveal important information about the evolution of disturbances responsible for blazar flares. Early results indicated that such rotations might be coincident with unusual gamma-ray activity of such sources. The RoboPol program for the polarimetric monitoring of statistically complete samples of blazars was developed in 2013 to systematically study this class of events and their possible connection with gamma-ray flares. RoboPol uses an innovative polarimeter installed at the 1.3m telescope of the University of Crete, and it is a collaboration between the University of Crete, Caltech, the Max-Planck Institute for Radio Astronomy, the Inter-University Centre for Astronomy and Astrophysics in India, and the Nicolaus Copernicus University in Poland. I will review the results of the 4-year aggressive, high-cadence gamma-ray—loud blazar monitoring with RoboPol, including the classification of the optopolarimetric properties of gama-ray—loud blazars, the statistical properties of polarization rotations, and their, now confirmed, relation to gamma-ray activity in blazar jets. Speaker: Ioannis Myserlis (Max-Planck-Institut für Radioastronomie) • 2:00 PM 3:30 PM Neutrinos Athenian Room (The Athenaeum) ### Athenian Room #### The Athenaeum Convener: Markus Ahlers (Niels Bohr International Academy, Niels Bohr Institute) • 2:00 PM Prompt neutrinos from heavy flavors 30m Neutrinos from charmed hadrons produced by cosmic ray interactions with air nuclei are the main background to high energy astrophysical neutrino flux measurements. Recent evaluations of the prompt neutrino flux from charm will be reviewed, including approaches using next-to-leading order QCD, the dipole model and kT factorization. Nuclear corrections and the impact of multi-component models of the incident cosmic ray flux will be discussed. Speaker: Mary Hall Reno • 2:30 PM New Measurement of Atmospheric Neutrino Oscillations with IceCube 15m The DeepCore infill array of the IceCube Neutrino Observatory enables observations of atmospheric neutrinos with energies as low as 5 GeV. Using a set of 40,000 neutrino events with energies ranging from 5.6 - 56 GeV recorded during three years of DeepCore operation, we measure the atmospheric oscillation parameters\theta_{23}$and$\Delta m^2_{32}$with precision competitive with long-baseline neutrino experiments, by observing distortions in the neutrino energy-zenith angle distribution. Our measurements are consistent with those made at lower energies, and prefer a value of$\theta_{23}$close to maximal. Speaker: Tyce DeYoung (Michigan State University) • 2:45 PM Solar Atmospheric Neutrinos: A New Neutrino Floor for Dark Matter Searches 15m As is well known, dark matter direct detection experiments will ultimately be limited by a "neutrino floor," due to the scattering of nuclei by MeV neutrinos from, e.g., nuclear fusion in the Sun. Here we point out the existence of a new "neutrino floor" that will similarly limit indirect detection with the Sun, due to high-energy neutrinos from cosmic-ray interactions with the solar atmosphere. We have two key findings. First, solar atmospheric neutrinos ≲1 TeV cause a sensitivity floor for standard WIMP scenarios, for which higher-energy neutrinos are absorbed in the Sun. This floor will be reached once the present sensitivity is improved by just one order of magnitude. Second, for neutrinos ≳1 TeV, which can be isolated by muon energy loss rate, solar atmospheric neutrinos should soon be detectable in IceCube. Discovery will help probe the complicated effects of solar magnetic fields on cosmic rays. These events will also be backgrounds to WIMP scenarios with long-lived mediators, for which higher-energy neutrinos can escape from the Sun. Speaker: Kenny Chun Yu Ng (Weizmann Institute of Science) • 3:00 PM Search for Solar Atmospheric Neutrinos with IceCube 15m High-energy neutrinos are expected to be produced in cosmic-ray interactions with the solar atmosphere. The resulting neutrino flux is expected to offer insights into cosmic ray transport in the inner solar system and on solar magnetic fields. Besides the high theoretical interest in solar atmospheric neutrinos, an observed signal could be the first high-energy neutrino point source and valuable for calibration. Preliminary selection criteria and optimization studies will be discussed. We present sensitivities and the prospects to observe the solar atmospheric neutrino signal with IceCube data. The interplay with on-going dark matter searches from the Sun will be discussed. Speaker: Carsten Rott (Sungkyunkwan University) • 3:15 PM High energy neutrinos from the Sun 15m In this talk I will discuss the production of high-energy neutrinos from interactions of cosmic rays with the solar atmosphere. Production of solar atmospheric neutrinos has been previously considered in the literature both as a potential source of high-energy neutrinos and as an irreducible background for dark matter searches. In our new calculation we estimate the uncertainties that arise from the solar atmosphere and hadronic interaction models. We further improve on previous calculations by considering neutrino oscillations in the propagation of neutrinos through the Sun. We predict that current event selections should observe ~ 1 event per year in detectors such as IceCube or the proposed mediterranean neutrino observatory, Km3Net. Finally, we put this rate in the context of indirect dark matter searches from the Sun by calculating the high-energy solar neutrino floor, which is analogous to the low-energy solar neutrino floor in dark matter direct detection experiments. Speaker: Carlos Arguelles (MIT) • 3:30 PM 4:00 PM Coffee break 30m Oak Room (The Athenaeum) ### Oak Room #### The Athenaeum • 4:00 PM 6:15 PM Dark matter Small Theater (The Athenaeum) ### Small Theater #### The Athenaeum Convener: C Eric Dahl (Northwestern University) • 4:00 PM LUX, and the Combatting of the WIMP Lamppost Effect 15m New results from the Large Underground Xenon (LUX) detector, a 100-kg-scale, 2-phase xenon direct dark matter search experiment, will be shared. Dark matter, the missing ~25% of the mass-energy content of the universe, is sought in new ways, using effective field theory operators to extend the search to higher-mass Weakly Interacting Massive Particles (WIMPs), spin-dependent interaction operators, and electron instead of nuclear recoil, to seek axions. In addition, 2-neutrino double electron capture of 124Xe will be explored. Lastly, both old and new calibrations and position and energy reconstruction techniques will be reviewed, in the context of the new background and signal models being developed by LUX which will be expanded to higher energies and with inclusion of pulse-shape discrimination. Speaker: Prof. Matthew Szydagis (University at Albany) • 4:15 PM The Next-Generation Dark Matter Project, LUX-ZEPLIN 15m Xenon-based dark matter experiments have been leading the field of direct detection for a decade now, as realized most recently by the PandaX, LUX, and now XENON1T results, setting increasingly stringent limits on WIMP scattering. The near-future commencement of construction of LUX and ZEPLIN’s 10-ton-scale scale-up, next-generation successor, LZ, will be discussed here. We plan on achieving our baseline sensitivity of 2.3 x 10^-48 cm^2 for a WIMP of 40 GeV/c^2 rest mass, with a 5.6-ton fiducial mass in a two-phase xenon time-projection chamber. LZ has recently passed its final CD-2/3 approvals from the DOE, and unveiled its design details, background estimates, and projected sensitivities for different types of dark matter in its technical design Report. These will all be presented. Speaker: Prof. Matthew Szydagis (University at Albany, SUNY) • 4:30 PM First result of XENON1T 15m Understanding the properties of dark matter particle is a fundamental problem in particle physics and cosmology. The search of dark matter particle scattering off nuclei target using ultra-low background detector is one of the most promising technology to decipher the nature of dark matter. The XENON1T experiment, which is a dual phase detector with ~2.0 tons of xenon running at the Gran Sasso Laboratory in Italy, is designed to lead the field of dark matter direct detection. Since November 2016, the XENON1T detector is continuously taking data, with a background rate of more than one order of magnitude lower than any current generation dark matter search experiment. In this talk, I will present the first dark matter search results from XENON1T. Details about the XENON1T detector as well as the data analysis techniques will also be covered. Speaker: Dr Lin Qing (Columbia University) • 4:45 PM Dark matter search results from the PandaX-II experiment 15m The PandaX project consists of a series of xenon-based experiments, located at China JinPing underground Laboratory. The current experiment, PandaX-II, is a direct dark matter search experiment with a 500 kg-scale liquid xenon dual-phase time projection chamber. PandaX-II started physics data taking in 2016. In this talk we report latest results and the current status of the PandaX-II experiment. Speaker: Prof. Yong Yang (Shanghai Jiao Tong University (CN)) • 5:00 PM Direct dark matter search with the CRESST-III experiment 15m The CRESST (Cryogenic Rare Event Search with Superconducting Thermometers) experiment aims at the direct detection of dark matter particles via their elastic scattering off nuclei. The target material consists of scintillating CaWO$_4$single crystals operated as cryogenic detectors at a temperature of ~10mK. For several years, these crystals have successfully been produced within the collaboration at the Technical University of Munich (TUM) and a significant improvement in radiopurity could be achieved. In CRESST-II Phase 2, an extended physics run between 2013 and 2015, the experiment demonstrated its leading sensitivity in the field of direct searches for dark matter masses below ~1.7GeV/c$^2$. A further detector optimization for the search of low-mass dark matter particles was performed for CRESST-III, whose Phase 1 started taking data in summer 2016. In this contribution the performance of the CRESST-III detectors as well as preliminary results will be presented. Requirements and perspectives for the upcoming CRESST-III Phase 2, in particular with respect to radiopurity, will be discussed. Speaker: Andrea Münster (Technical University of Munich (TUM)) • 5:15 PM Dark matter searches with the PICO bubble chambers 30m The PICO collaboration uses superheated fluid detectors to attempt to directly detect interactions between dark matter particles and ordinary matter. These detectors can be operated in conditions under which they are insensitive to gamma and beta radiation, typically the dominant backgrounds for direct dark matter searches. The PICO-60 bubble chamber is located 2km underground at SNOLAB in Sudbury, Ontario, where neutron backgrounds from cosmic rays are strongly suppressed. These backgrounds are further suppressed by a water tank surrounding the chamber, and by the selection and clean handling of very radiopure components. Piezoacoustic transducers detect the sound of bubble nucleation, which can be used to distinguish between nuclear recoils and U/Th chain alpha decays, the predominant background in superheated fluid dark matter searches. During its first physics run the PICO-60 C$_3$F$_8$bubble chamber was operated at a thermodynamic energy threshold of 3.3 keV, acquiring a background-free WIMP-search exposure of 1167 kg-days. A similar exposure was then acquired at 2.4 keV and is currently under analysis. Its successor, PICO-40L, will begin commissioning in the latter part of 2017. This detector has an inverted vertical orientation, intended to eliminate potential backgrounds caused by water droplets, particulates, and surface tension effects in previous chambers. It is intended to act as a prototype and proof-of-principle for the proposed ton-scale bubble chamber PICO-500. Speaker: Scott Fallows (University of Alberta) • 5:45 PM Search for hidden-photon Dark Matter with FUNK 15m Many extensions of the Standard Model of particle physics predict a parallel sector of at least one new U(1) symmetry, giving rise to hidden photons. If produced non-thermally in the early universe, these hidden photons can be candidate particles for cold Dark Matter. Hidden photons are expected to kinetically mix with regular photons. If hidden photons pass through a conducting surface a tiny electromagnetic signal is produced. Due to the kinematics of the process, these photons are emitted almost perpendicularly to the surface. The corresponding photon frequency is given by the mass of the hidden photons. In this contribution we present results of a search for dark photons in the mass range from 2 to 8 eV using a spherical metallic mirror of 14 m^2 area. We will also discuss future Dark Matter searches in the eV and sub-eV range by application of different detectors for electromagnetic radiation. Speaker: Ralph Richard Engel (KIT - Karlsruhe Institute of Technology (DE)) • 4:00 PM 6:00 PM Galactic sources Macedonian Room (The Athenaeum) ### Macedonian Room #### The Athenaeum Convener: Yves Gallant (LUPM, CNRS/IN2P3, U. de Montpellier) • 4:00 PM New insights on particle acceleration at non-relativistic shocks 30m I present the results of large kinetic simulations of particle acceleration at non-relativistic collisionless shocks, which allow an ab-initio investigation of diffusive shock acceleration (DSA) at the blast waves of supernova remnants, the most prominent sources of Galactic cosmic rays (GCRs). Ion acceleration efficiency and magnetic field amplification are obtained as a function of the shock properties and compared with theoretical predictions and multi-wavelength observations of individual remnants. In particular, I will focus on two new results: 1) the origin of the chemical enhancement of heavy elements observed in GCRs as naturally due to DSA, and 2) the re-acceleration of energetic particle “seeds” and its phenomenological implications. Speaker: Prof. Damiano Caprioli (University of Chicago) • 4:30 PM Fermi Acceleration in Relativistic Shocks 15m I will discuss cosmic ray production at relativistic shocks. I will emphasize the differences expected for relativistic shocks compared to non-relativistic ones and examine possible applications such as relativistic supernovae and gamma ray bursts. Speaker: Donald Ellison • 4:45 PM Particle acceleration at pulsar-wind termination shocks 15m The X-ray emission from pulsar wind nebulae arises from particles accelerated at the shock that terminates the relativistic, strongly magnetized pulsar wind. However, conventional theories of particle acceleration break down at this shock, because the combination of low particle density and strong magnetic field places it outside the domain of validity of MHD. We first discuss how particles are, nevertheless, injected into a first-order-Fermi-like process and accelerated. We then study their acceleration in the equatorial region of the termination shock. To do so, we integrate the individual trajectories of electrons and positrons, in the test-particle limit, in the background electromagnetic fields present in that region. We find that the spectrum of accelerated electrons (or positrons, depending on the polarity) is significantly harder than$E^{-2.2}$. We calculate the resulting synchrotron spectrum, and compare our results with Chandra observations of the X-ray spectrum of the Crab nebula. I am also submitting an abstract to the track "cosmic rays". Speaker: Gwenael Giacinti (MPIK Heidelberg) • 5:00 PM Pulsars with MAGIC 15m MAGIC is a stereoscopic system of two imaging atmospheric Cherenkov telescopes, located at the Roque de los Muchachos Observatory, in La Palma (Spain) sensitive to gamma rays from few tens of GeV to tens of TeV. Pulsar physics is one of important topics in the MAGIC scientific program. In 2008, MAGIC for the first time detected VHE gamma-rays demission above 25 GeV from the Crab pulsar. Ever since, crab observations with MAGIC have beenIn this talk, we will present the recent scientific results derived from observations of the Crab pulsar, we will describe the technical innovations of MAGIC for the study of pulsars at a few tens of GeV, and will give an outlook to future pulsar observations at very-high-energy gamma rays and their relevance to understanding these extreme celestial objects. providing important results for the understanding of pulsar physics. Speaker: Jezabel Rodriguez Garcia (Max-Planck-Institut fuer Physik) • 5:15 PM The Sun as a new laboratory for cosmic rays, gamma rays, neutrinos, and dark matter 15m The Sun must shine brightly in GeV—TeV gamma rays and neutrinos. These particles are produced by the interactions of cosmic rays with solar matter and radiation. Additional fluxes may be caused by the annihilation of dark matter in the solar core, perhaps with the eventual particles produced outside of the Sun through the decay of metastable mediators. Importantly, a new generation of experiments is reaching the sensitivity required to detect the Sun at high energies. In gamma rays, the Sun has been detected in the GeV range by Fermi and will soon be studied in the TeV range by ARGO-YBJ, HAWC, and LHAASO. In neutrinos, IceCube is nearing the sensitivity required to detect TeV neutrinos. I will detail the physics prospects for what these observations will teach us about cosmic rays in the inner solar system, solar magnetic fields, and dark matter. This talk will highlight work from our group, including arXiv:1508.06276, arXiv:1612.02420, arXiv:1703.04629, arXiv:1703.10280, as well as the rapid growth in interest from other groups. Speaker: Bei Zhou (CCAPP, OSU) • 5:30 PM VERITAS Observations of Galactic Binary Systems 15m Only a handful of High Mass X-ray Binaries (HMXB) in our galaxy are known emitters of TeV gamma rays. The variable VHE emission from these sources are generally attributed to modulation by their orbital periods but the particle acceleration and gamma-ray production processes in these HMXBs are not well understood. In its 10 years of operation, VERITAS has observed 2 of these TeV emitting HMXBs, LS I +61 303 and HESS J0632+057 for more than 450 hours, conducting many multi-wavelength campaigns. The results from recent observations, long-term monitoring and multi-wavelength study with X-ray (Swift-XRT) and GeV (Fermi-LAT) for LS I +61 303 and HESS J0632+057 are discussed. Besides these two TeV binaries, an outline of the binary discovery program by VERITAS is presented with particular emphasis on PSR J2032+4127, the long period (45-50 years) binary in a highly eccentric orbit with the Be star MT91 213. This system could be the origin of very high energy emission from the unidentified source TeV J2032+4130. We present the status of observations of PSR J2032+4127, preliminary results and the plan for continued monitoring through periastron in 2017. Speaker: Payel Kar (University of Utah, VERITAS Collaboration) • 5:45 PM Finale of a Quartet: Hints on Supernova Formation 15m Supernovae (SNe) and their remnants are important cosmic ray sources. However, the origin of one major type of SNe, the Type Ia, is still not well understood. Two most popular hypotheses are the single-degenerate scenario, where one white dwarf (WD) accretes matter from its giant companion until the Chandrasekhar limit is reached, and the double-degenerate scenario, where two WDs merge and explode. We focus on the second scenario. It has long been realized that binary WD systems normally take extremely long time to merge via gravitational waves and it is still unclear whether WD mergers can fully account for the observed SN Ia rate. Recent effort has been devoted to the effects of introducing a distant tertiary to the binary system. The standard “Kozai-Lidov” mechanism can lead to high eccentricities of the binary WDs, which could lead to direct collisions or much efficient energy dissipation. Alternatively, we investigate the long-term evolution of the hierarchical quadruple systems, i.e. WD binary with a binary companion, which are basically unexplored, yet they should be numerous. We explore their interesting dynamics and find that the fraction of reaching high eccentricities is largely enhanced, which hints on a higher WD merger rate than predicted from triple systems with the same set of secular and non-secular effects considered. Considering the population of quadruple stellar systems, the quadruple scenario might contribute significantly to the overall rate of Ia SNe. Speaker: Xiao Fang (The Ohio State University) • 4:00 PM 6:00 PM Gamma rays Corinthian Room (The Athenaeum) ### Corinthian Room #### The Athenaeum Convener: Maria Petropoulou (Purdue University) • 4:00 PM Gamma-ray and optical polarimetric monitoring of GeV bright blazars 15m Blazars are thought to possess a relativistic jet that is pointing toward the direction of the Earth and the effect of relativistic beaming enhances its apparent brightness. Although numerous measurements have been performed, the mechanisms behind jet variability, creation, and composition are still debated. We performed simultaneous gamma-ray and optical photopolarimetry observations of 45 blazars with Fermi/LAT and Kanata telescope between 2008 July and 2014 December to investigate the mechanisms of variability and search for a basic relation between the several subclasses of blazars. Consequently, we found that a correlation between the gamma-ray and optical flux might be related to gamma-ray luminosity and the maximum polarization degree might be related to gamma-ray luminosity or the ratio of gamma-ray to optical flux. These results imply that low gamma-ray luminosity blazars emit from multiple regions. Speaker: Dr Ryosuke Itoh (Tokyo Institute of technology) • 4:15 PM Blazar Radio and Optical Survey (BROS): A New Catalog of Blazar Candidates 15m By using deep radio source catalogs currently available, we present a new blazar candidate catalog, BROS, which includes 56314 sources located at declination$\delta > -40^{\circ}$and outside the Galactic Plane ($|b| > 10^{\circ}$). We picked up flat-spectrum radio sources of$\alpha > -0.5$($\alpha$is defined as$F_{\nu} \propto \nu^{\alpha}$) from 0.15 GHz TGSS and 1.4 GHz NVSS catalogs. Then, we identified their optical counterparts by cross-matching with the Pan-STARRS1 data. Color-color and color-magnitude plots for the selected flat-spectrum radio sources clearly showed two populations, “quasar-like” and “elliptical-galaxy-like” sequences. We emphasize that the latter population emerged for the first time and is missed by previous CRATES catalog because of the higher radio flux threshold. We found that the color-magnitude relation of nearby bright elliptical galaxies up to z=0.3 follows the “elliptical-galaxy-like" sequence. The index of the logN-logS distribution for this sample is$1.44\pm0.06$, supporting the interpretation of "nearby" because the measurement is consistent with a value for a static Euclidean universe. This BROS catalog is useful to search for electromagnetic counterparts of ultra-high-energy cosmic rays as well as PeV neutrions recently detected by IceCube, thus a powerful catalog in the era of multi-messenger astronomy. We also emphasize that this BROS catalog includes nearby ($z \leq 0.3$) BL Lac objects, a fraction of which would be TeV emitters and detectable by future Cherenkov Telescope Array. We will soon make this catalog available once published. Speaker: Dr Yasuyuki Tanaka (Hiroshima University) • 4:30 PM Challenges in reconciling observations and theory of the brightest high-energy flare ever of 3C 279 15m Recent high-energy missions have allowed keeping watch over quasars in flaring states, which provide deep insights into the engine powered by supermassive black holes. However, having a quasar caught in a very bright flaring state is not easy requiring long surveys. Therefore, the observation of such flaring events represents a goldmine for theoretical studies. Such a flaring event was captured by the INTEGRAL mission in June 2015 while performing its today’s deepest extragalactic survey when it caught the prominent quasar 3C 279 in its brightest flare ever recorded at gamma-ray energies. The flare was simultaneously recorded by the Fermi-LAT mission, by the Swift mission, and by observations ranging from UV, through optical to the near-IR bands. The derived snapshot of this broad spectral energy distribution of the flare has been modeled in the context of a one-zone radiation transfer leptonic and lepto-hadronic models constraining the single emission components. I will discuss results and challenges faced by trying to reconcile these observations and theory. Also implications for the detection of VHE gamma rays by Atmospheric Cherenkov Telescopes for such a flare will be discussed. Speaker: Eugenio Bottacini (University of Padova) • 4:45 PM Flat-Spectrum Radio-Quasars with H.E.S.S. II 15m With the installation of a fifth 28-m diameter telescope in the center of the array, the H.E.S.S. telescope array is now in its phase II, characterized by a low energy threshold below 100 GeV. The low-energy window is particularly appealing for extragalactic gamma-ray astronomy, because it allows the study of more distant sources, as well as sources characterized by softer spectra. In particular, flat-spectrum radio-quasars (FSRQs), which dominate the Fermi-LAT extragalactic sky but are rarer in the very-high-energy (VHE) gamma-ray band due to their low-frequency SED peak, are among the most interesting targets for H.E.S.S. II observations. In this contribution I will review some recent results from H.E.S.S. II observations on FSRQs, including the discovery of VHE emission from PKS 0736+017, the detection of 3C 279 during the 2015 outburst, and the detection of PKS 1510-089 during the 2016 outburst. Speaker: Matteo Cerruti (CNRS, LPNHE) • 5:00 PM High-Energy Gamma Rays and Neutrinos from Nearby Radio Galaxies 15m Radio Galaxies are the most likely class of sources for the diffuse flux of high-energy neutrinos reported by the IceCube Collaboration as suggested by multi-messenger data. Here, the gamma-ray spectrum from four nearby radio galaxies (Centaurus A, PKS 0625-35, NGC 1275, and IC 310) is analyzed in order to constrain the spectral shape and intensity of their respective injected emission. Our analysis handles gamma ray propagation though galactic and extragalactic environments accounting for the effects of electromagnetic cascades. Assuming interactions of cosmic ray protons with gas are the origin of this gamma-ray emission, we calculate the resulting neutrino flux for the selected sources. While the predicted neutrino fluxes are consistent with constraints published by the IceCube and ANTARES Collaborations, they consistently fall within an order of magnitude below the current point source sensitivity. The prospects appear very encouraging for the future detection of neutrino emission from the nearest radio galaxies.predicted from each of these sources. Although this scenario is consistent with the constraints published by the IceCube and ANTARES Collaborations, the predicted fluxes consistently fall within an order of magnitude of the current point source sensitivity. The prospects appear very encouraging for the future detection of neutrino emission from the nearest radio galaxies. Speaker: Mr Carlos Blanco (University of Chiago, Department of Physics) • 5:15 PM The Compton Spectrometer and Imager: Results from the 2016 Super-Pressure Balloon Campaign 15m The Compton Spectrometer and Imager is a 0.2-5 MeV Compton telescope capable of imaging, spectroscopy and polarimetry of astrophysical sources. Such capabilities are made possible by COSI's twelve germanium cross-strip detectors, which provide for high efficiency, high resolution spectroscopy, and precise 3D positioning of photon interactions. In May 2016, COSI took flight from Wanaka, New Zealand on a NASA super-pressure balloon. For 46 days, COSI floated at a nominal altitude of 33.5 km, continually telemetering science data in real-time. The payload made a safe landing in Peru, and the hard drives containing the full raw data set were recovered. Analysis efforts have resulted in detections of various sources such as the Crab Nebula, Cyg X-1, Cen A, Galactic Center e+e- annihilation, and the long duration gamma-ray burst GRB 160530A. In this presentation, I will provide an overview of our main results, which include measuring the polarization of GRB 160530A, and our image of the Galactic Center at 511 keV. Additionally, I will summarize results pertaining to our detections of the Crab Nebula, Cyg X-1, and Cen A. Speaker: John Tomsick • 5:30 PM Spectral and Temporal Behaviour of Mrk 501 in Gamma Rays 15m The blazar Mrk 501 is a well-known BL-Lac type object emitting very high energy photons interacting with the EBL despite the modest redshift and is highly variable across wavelengths down to timescales of a few minutes at TeV energies. This makes it an excellent laboratory for studying particle acceleration and radiative emission processes in jets through the spectral and temporal properties of the observed emission. It also allows us to constrain the Extragalactic Background Light (EBL) and Lorentz Invariance Violation (LIV). H.E.S.S. has observed Mrk 501 during some of its active states at the highest energies in 2014, triggered by FACT which continuously monitors it, profiling its long-term TeV behaviour as Fermi-LAT does at GeV energies. Here, we present the temporal and spectral behaviour of Mrk 501 at gamma ray energies. We compute the gamma ray power spectral density as well as the energy spectrum for the highest TeV flux state observed by H.E.S.S. and FACT in June 2014 that shows rapid variability and contrast it with the long term average behaviour. We also derive strong constraints on the LIV scale via the non-detection of EBL opacity modifications and from time-of-flight studies from the H.E.S.S. flare data. Speaker: Dr Nachiketa Chakraborty (Max-Planck-Institut fuer Kernphysik) • 5:45 PM Free 15m Free • 4:00 PM 6:00 PM Neutrinos Athenian Room (The Athenaeum) ### Athenian Room #### The Athenaeum Convener: Markus Ahlers (Niels Bohr International Academy, Niels Bohr Institute) • 4:00 PM Measurement of neutrino events above 1 TeV with contained vertices in IceCube 15m IceCube is a cubic kilometer scale detector in the deep antarctic ice. The 5160 deployed digital optical modules lead to the unambiguous detection of astrophysical neutrinos using events starting inside the detector with deposited energies above 60 TeV. Lowering the energy threshold down to 1 TeV, while maintaining a >90% neutrino-pure sample, greatly increases statistics. We will present the latest results of this data sample, containing more than 7000 all-sky neutrino-induced cascades and tracks. The data set allows a more precise measurement of the astrophysical spectrum, down to the atmospherically dominated region. Astrophysical models involving a second power-law component will be tested. Furthermore, we will present improved limits on the contribution of neutrinos from charmed mesons to the atmospheric flux. Having a significant contribution of both tracks and cascades in the same data sample allows to constrain the neutrino flavor space. Speaker: Nancy Wandkowsky (University of Wisconsin-Madison) • 4:15 PM High Energy Astrophysical Neutrino Flux Measurement Using Neutrino-induced Cascades Observed in 4 Years of IceCube Data 15m We report a new measurement of the diffuse flux of high energy extraterrestrial neutrinos from the whole sky with energies of O(1 TeV) and above, that is predominantly sensitive to electron and tau flavors. We analyzed 4 years of IceCube data recorded from 2012-2015 focusing on neutrino-induced cascades. Cascades provide good energy resolution and have a lower atmospheric neutrino background contribution than muon neutrinos. A new event selection has been developed combining straight cuts with gradient boosted multi-class decision trees to isolate cascades with increased efficiency over previous methods, resulting in the largest cascade sample obtained by IceCube to date. Our methods achieve a neutrino purity of better than 90%. At energies above 20 TeV the contribution of muon neutrinos to the total number of expected astrophysical neutrinos in this cascade sample is estimated to be 10%. At these energies the extra-terrestrial component dominates the observed spectrum and is well described by a single, unbroken power-law. We will discuss preliminary fit results and study the possibility of a spectral hardening at the upper end of the spectrum by allowing a second power-law component to enter our flux model. Speaker: Mr Hans Niederhausen (Stony Brook University) • 4:30 PM Searches for astrophysical sources of neutrinos using cascade events in IceCube 15m The IceCube neutrino observatory has observed a flux of high-energy astrophysical neutrinos using both track events from muon neutrino interactions and cascade events from interactions of all neutrino flavors. Searches for astrophysical neutrino sources have focused on track events due to the significantly better angular resolution of track reconstructions. To date, no such sources have been confirmed. In this talk we turn our attention to complementary and statistically-independent source searches using cascade events with deposited energies as small as 1 TeV. Compared to the classic approach using tracks, the cascade channel offers improved sensitivity to sources in the southern sky, especially if the emission is spatially extended or follows a soft energy spectrum. We will show results from a first search using 263 cascades collected from May 2010 to May 2012, as well as projected sensitivity estimates for an upcoming analysis of six years of data. Speaker: Mike Richman • 4:45 PM A new search for multi-flavour PeV neutrinos with IceCube 15m PeV neutrinos detected by the IceCube observatory are the highest-energy extraterrestrial elementary particles ever seen on Earth. More knowledge on PeV neutrinos such as seeing a spectral cut-off would help understand the possible connection to the sources of ultra-high energy cosmic rays. A new selection has been developed for PeV neutrinos which are not selected by the existing high-energy searches. The new channel has been optimised for partially-contained cascades generated via Glashow resonance. It has then been combined with samples of high-energy starting events and extremely-high-energy tracks to determine the characteristics of the high-energy end of the diffuse spectrum. In this talk, results on the cut-off energy will be shown and constraints on scenarios which predict cosmogenic PeV neutrinos will be discussed. Speaker: Lu Lu (Chiba University) • 5:00 PM Improving the angular resolution in IceCube cascade reconstruction 15m Neutrino interactions occurring in IceCube require accurate reconstruction techniques to quantify the neutrino's energy and arrival direction. At the highest energies, the angular resolution of IceCube is limited primarily by ice property uncertainties. Previous studies have shown that a perfect knowledge of the ice may improve cascade angular resolutions by a factor of two or more. We present a new method for evaluating the effect of ice model uncertainties and explore several channels by which the reconstructed angular resolution may be improved. Speaker: Tianlu Yuan (UW Madison) • 5:15 PM A new IceCube starting track event selection and realtime stream 15m IceCube analyses which look for an astrophysical neutrino signal in the southern sky face a large background of atmospheric neutrinos and muons created in cosmic ray air showers. Earlier, it was found that rejecting events that deposit energy in the outer region of the detector reduces not only the muon background, but also the atmospheric neutrino background in the southern sky due to the atmospheric self-veto effect. However, using outer layer fiducial cuts reduces the size of the detector and leads to a selection optimized for cascades. In this event sample, we select for muon tracks which have a starting vertex contained inside the detector. By using the improved directional reconstruction from muons, the selection determines a veto region behind the starting vertex for each event and calculates the likelihood for not observing a hit on the IceCube optical modules (DOMs) in the veto region. These cuts give a selection which has a high astrophysical neutrino purity above 10 TeV in the southern sky. We will present our most recent results from our neutrino point source and diffuse flux searches and provide a first look at the realtime events stream derived from the selection. Speaker: Sarah Mancina (University of Wisconsin -- Madison) • 5:30 PM IceCube Search for Galactic Neutrino Sources using the HAWC 2HWC Catalog 15m We present prospects for IceCube to detect neutrino emission from Galactic TeV gamma-ray sources outlined in the HAWC Observatory's recently published 2HWC catalog. We do this by evaluating the sensitivity of two analyses using IceCube data. The first is a stacked analysis of promising point sources from the catalog which are chosen based on their high TeV photon fluxes and lack of association with known pulsar wind nebula. Here we assume the highest energy photons originate from the decay of charged pions produced by hadronic interactions at each source. The second is a template analysis using the full Galactic plane morphology measured by HAWC. This morphology should trace neutrino emission if pion decay predominantly occurs in the environment surrounding identified HAWC sources. Speaker: Joshua Wood (University of Wisconsin, Madison) • 5:45 PM Free 15m Free • 4:00 PM 6:00 PM Particle physics Spartan Room (The Athenaeum) ### Spartan Room #### The Athenaeum Convener: Nicole Bell (University of Melbourne) • 4:00 PM New Direct Detection Signals from Dark Matter Bound States 15m I will discuss new signatures in direct detection experiments if part or all of the dark matter particles in nature are in the form of bound states. It will allow the sub-GeV dark matter candidates to be much more visible at dark matter and neutrino detectors. Speaker: Yue Zhang • 4:15 PM Capture and Decay of Electroweak WIMPonium 15m The spectrum of Weakly-Interacting-Massive-Particle (WIMP) dark matter generically possesses bound states when the WIMP mass becomes sufficiently large relative to the mass of the electroweak gauge bosons. The presence of these bound states enhances the annihilation rate via resonances in the Sommerfeld enhancement, but they can also be produced directly with the emission of a low-energy photon. I will present a calculation of the rate for SU(2)-triplet dark matter (the wino) to bind into WIMPonium -- which is possible via single-photon emission for wino masses above 5 TeV for relative velocity v < O(10^{-2}) -- and the subsequent decays of these bound states. I will also present results with applications beyond the wino case, e.g. for dark matter inhabiting a general nonabelian dark sector. Speaker: Patrick Fitzpatrick (Center For Theoretical Physics, Massachusetts Institute of Technology) • 4:30 PM The LHC Dark Matter Working Group 15m The LHC Dark Matter Working Group (LHC DM WG) brings together theorists and experimentalists to provide the benchmark models, interpretation, and characterisation needed for a robust and broad set of searches for dark matter at the LHC. I will discuss the work of the LHC DM WG, and its predecessor the ATLAS/CMS Dark Matter Forum---the interaction between theory and experiment, the types of signals being considered for LHC Run-2 searches, the evolving interpretation of the LHC results alongside direct and indirect detection, and the future. Speaker: Antonio Boveia (Ohio State University) • 4:45 PM Search for long-lived particles at CMS 15m New particles with long lifetimes are introduced by many extensions to the standard model and would produce striking and non-conventional signatures in collider experiments such as long-lived charged particles, highly displaced jets, and particles that come to a rest within the detector and later decay. We present the results of several recent searches for long-lived particles with the CMS experiment in Run II of the LHC. Speaker: Brian Francis (Ohio State University (US)) • 5:00 PM Search for low mass dijet resonances at CMS 15m We present several complementary searches for low mass dijet resonances using a 35.9 inverse femtobarn data set of proton-proton collisions at 13 TeV collected with the CMS experiment at the LHC in 2016. One search uses the CMS scouting data stream concept to record larger data rates than otherwise possible. Another search uses an initial state radiation jet to overcome trigger thresholds and search for boosted dijet resonances, whose decay products are merged into a single jet. Novel jet substructure techniques are used to avoid sculpting the distribution of the jet mass distribution and the dominant background is estimated from data. Both searches are interpreted in the context of leptophobic vector resonances and simplified models of dark matter with a leptophobic mediator. This approach has also been extended to the search for boosted Higgs bosons decaying to bottom quark-antiquark pairs. Speaker: Javier Mauricio Duarte (Fermi National Accelerator Lab. (US)) • 5:15 PM Rare, Exotic, and Invisible Higgs Decays at CMS 15m We present the latest results in the search for rare, exotic, and invisible Higgs boson decays in proton-proton collision events collected with the CMS detector at the LHC. The rich experimental program we describe, which includes searches for lepton flavor violation and decays to dark matter and light scalars, provides a wide ranging probe for physics beyond the standard model. Speaker: Ben Kreis (Fermi National Accelerator Lab. (US)) • 5:30 PM Global Fits of the MSSM with GAMBIT 15m The wide range of probes of physics beyond the standard model (BSM) lead to the need for tools that consistently combine experimental results to make the most robust possible statements about the validity of new physics theories and the preferred regions of their parameter space. In this talk, I will introduce a new publicly released code for such studies: GAMBIT, the Global and Modular BSM Inference Tool. GAMBIT is a flexible and extensible framework for global fits of essentially any BSM theory. The code currently incorporates constraints from the dark matter relic density, direct and indirect dark matter searches, limits on production of new particles from the LHC and LEP, complete flavor constraints from LHCb, LHC Higgs production and decay measurements, and various electroweak precision observables. I will discuss the code’s capabilities and results of scans of the parameter space of the Minimal Supersymmetric Standard Model. Speaker: Jonathan Cornell (McGill University) • 5:45 PM Collider and Indirect Singatures of Non-Minimal Dark Matter sectors 15m Recent Fermi-LAT observations of dwarf spheroidal galaxies in the Milky Way have placed strong limits on the gamma-ray flux from dark matter annihilation. In order to produce the strongest limit on the dark matter annihilation cross-section, the observations of each dwarf galaxy have typically been “stacked” in a joint-likelihood analysis, utilizing optical observations to constrain the dark matter density profile in each dwarf. These limits have typically been computed only for singular annihilation final states, such as b ̄ b or τ + τ . In this paper, we generalize this approach by producing an independent joint-likelihood analysis to set constraints on models where the dark matter particle annihilates to multiple final state fermions. We interpret these results in the context of the most popular simplified models, including those with s- and t-channel dark matter annihilation through scalar and vector mediators. We present our results as constraints on the minimum dark matter mass and the mediator sector parameters. Additionally, we compare our simplified model results to those of Effective Field Theory contact interactions in the high-mass limit. Speaker: Linda Carpenter (Ohio State University) • Wednesday, August 9 • 9:00 AM 12:18 PM Plenary session Davidson Theatre #### Davidson Theatre Conveners: Prof. Annika Peter (Center for Cosmology and AstroParticle Physics, The Ohio State University), James Beatty (Ohio State University) • 9:00 AM Fast Radio Bursts and CHIME 30m I review our present observational understanding of the mysterious new phenomenon of Fast Radio Bursts -- short (few ms) bursts of radio waves arriving from apparently cosmological distances -- as well as models for what these sources may be. I also describe the CHIME telescope, currently being built in Canada, and how it will impact this interesting puzzle. Speaker: Victoria Kaspi (McGill University) • 9:30 AM The new era of galactic cosmic rays 30m A new era in galactic cosmic rays physics has started with the precise and continuous observations from space experiments such as PAMELA and AMS-02. Their invaluable results are rewriting the theory of acceleration and propagation of cosmic rays. Both at high energies, where several new behaviors have been measured, challenging the accuracy of theoretical models, as well as at low energies, in the region affected by the solar modulation. These precise measurements are improving our knowledge of galactic cosmic rays, allowing detailed studies of acceleration, propagation and composition as it has never been done before. These measurements will serve as a high-precision baseline for distinguishing the background from the signal of possible exotic sources. In this review, the status of the latest measurements in galactic cosmic rays together with the current open questions and the future prospects are presented. Speaker: Veronica Bindi (University of Hawai'i at Manoa (US)) • 10:00 AM Coffee break 30m • 10:30 AM Ultra-High-Energy Cosmic Rays 30m In this talk I will review the status and prospects of understanding the physics of ultra-high-energy cosmic rays. Focusing on the progress made thanks to data of the Pierre Auger Observatory and Telescope Array, observations are discussed in the context of their implications for various source scenarios and remaining uncertainties are highlighted. The talk concludes with a summary of ongoing efforts to upgrade existing cosmic ray detectors and developing new ones with even larger aperture. Speaker: Ralph Engel (KIT - Karlsruhe Institute of Technology (DE)) • 11:00 AM Cosmological magnetic fields and particle acceleration in the laboratory 30m Magnetic fields are ubiquitous in the Universe. The energy density of these fields is typically comparable to the energy density of the fluid motions of the plasma in which they are embedded. Magnetic fields are also essential for the production of high energy cosmic rays. The standard theoretical model for the origin of these strong magnetic fields is through the amplification of tiny seed fields via turbulent dynamo to the level consistent with current observations. Here we demonstrate, using laser-produced colliding plasma flows, that turbulence is indeed capable of rapidly amplifying seed fields to equipartition with the turbulent fluid motions. These results support the notion that turbulent dynamo is responsible for the observed present-day magnetization of the Universe. We also show that such turbulent and magnetized plasmas can drive plasma instabilities that energize electrons above the thermal background, thus providing a possible injection mechanism for cosmic ray acceleration. We conclude by discussing future experiments at the National Ignition Facility laser to study second order Fermi acceleration. Speaker: Gianluca Gregori (University of Oxford) • 11:30 AM Cosmic-ray and gamma-ray anomalies and their interpretations 18m I will review several interesting anomalies in cosmic-ray (CR) and gamma-ray data and discuss possible interpretations, focusing on what they can reveal about the nature of CR sources and the physics of CR transport in the Galaxy. Speaker: Daniele Gaggero • 11:48 AM Dark Energy Survey Year 1 Cosmology Results 30m The first year of the Dark Energy Survey observations imaged 1321 square degree of the Southern sky in griz. We present measurements of galaxy clustering and weak gravitational lensing from this data set, and cosmological parameters inferred from these these two-point correlation functions in a blind analysis. Speaker: Dr Elisabeth Krause (Stanford) • 12:18 PM 2:00 PM Lunch 1h 42m • 2:00 PM 3:30 PM Cosmic rays Macedonian Room (The Athenaeum) ### Macedonian Room #### The Athenaeum Convener: nahee park (University of Chicago) • 2:00 PM Precision Measurement of 3He-to-4He ratio in Cosmic Rays with the Alpha Magnetic Spectrometer on the International Space Station 15m Knowledge of the energy dependence of the 3He-to-4He flux ratio (3He/4He) is important in understanding the propagation of cosmic rays. As 3He is assumed to be produced by interactions of heavier nuclei with the interstellar matter, the 3He/4He ratio is a powerful tool for determining the amount of interstellar material traversed by cosmic rays. AMS results are based on 9 million 3He events and 56 million 4He events collected in the first five years of operation onboard the ISS. The precise measurement of the 3He/4He ratio from 0.7 GeV/n to 10GeV/n is presented for the first time. The AMS results are unique and distinct from all the previous data. Speaker: Dr Francesca Giovacchini (CIEMAT (SPAIN)) • 2:15 PM Evidence for Stochastic Acceleration of Secondary Antiprotons by Supernova Remnants 15m Supernova remnants are known to be the main sources of galactic cosmic-rays. They could also be a possible explanation for rise of the positron fraction, if secondary positrons are produced and then accelerated around the supernova shock front. Yet, if secondary positrons are stochastically accelerated in such shocks, other secondary cosmic ray species will also be accelerated. Using recent measurements of the cosmic-ray antiproton and proton fluxes in the energy range of 1 – 1000 GeV, we study the contribution to the antiproton to proton ratio from stochastically accelerated secondary antiprotons in SNRs. We consider several well-motivated models for cosmic-ray propagation in the interstellar medium and marginalize our results over the uncertainties related to the antiproton production cross section and the time-, charge-, and energy-dependent effects of solar modulation. We find that the increase in the antiproton to proton ratio at energies above 100 GeV cannot be accounted for within the context of conventional cosmic-ray propagation models and that there is statistical evidence for an additional component that could be provided by the stochastically accelerated secondary antiprotons. Under the same conditions in SNRs, we show that accelerated secondary positrons, can account for a significant fraction of the observed positron flux excess. Speaker: Dr ILIAS CHOLIS (Johns Hopkins University) • 2:30 PM Impact of Cosmic Ray Transport on Galactic Winds 15m The role of cosmic rays generated by supernovae and young stars has very recently begun to receive significant attention in studies of galaxy formation and evolution due to the realization that cosmic rays can efficiently accelerate galactic winds. Microscopic cosmic ray transport processes are fundamental for determining the efficiency of cosmic ray wind driving. Previous studies focused on modeling of cosmic ray transport either via a constant diffusion coefficient or via streaming proportional to the Alfven speed. However, in predominantly neutral gas, cosmic rays can propagate faster than in the ionized medium and the effective transport can be substantially larger; i.e., cosmic rays can decouple from the gas. We perform three-dimensional magnetohydrodynamical simulations of patches of galactic disks including the effects of cosmic rays. Our simulations include the decoupling of cosmic rays from the neutral interstellar medium. We find that, compared to the ordinary diffusive cosmic ray transport case, accounting for the decoupling leads to significantly different wind properties such as the gas density and temperature, significantly broader spatial distribution of cosmic rays, and larger wind speed. These results have implications for X-ray, gamma-ray and radio emission, and for the magnetization and pollution of the circumgalactic medium by cosmic rays. Speaker: Ryan Farber (University of Michigan, Ann Arbor) • 2:45 PM Secondary production of cosmic ray anti-deuteron and anti-Helium3 15m We evaluated flux of cosmic ray anti-deuteron and anti-Helium3 from secondary astrophysical production. The production cross section at proton-proton collision is one of the most important input parameter to determine the secondary cosmic ray flux. However, composite (anti-)nuclei production cross section is very small and the cross section data at collider experiments is quite limited. That is why proton-heavy ion and heavy ion-heavy ion collision data are often used to determine anti-nuclei production cross sections in the literature. In heavy ion collision, physical volume of hadron emission region is larger than that of proton-proton collision. Also, in nuclear physics, it is known that composite nuclei production rate obeys a scaling law with the volume of emission region. However, this point has been neglected in the calculation of cosmic ray flux. We applied this scaling law to calculate anti-deuteron and anti-Helium3 flux. Our result is larger than the previous works by 1-2 orders of magnitudes. In particular, secondary anti-Helium3 flux could be within the reach of a five-year exposure of AMS-02. Speaker: Ryosuke Sato (Weizmann Institute of Science) • 3:00 PM Nearby Pulsars and The Cosmic Ray Positron Excess 15m Measurements of the Geminga and B0656+14 pulsars by HAWC and Milagro indicate that these objects generate significant fluxes of very high-energy electrons. From the very high-energy gamma-ray intensity and spectrum of these pulsars, one can calculate their expected contributions to the local cosmic-ray positron spectrum. From these considerations, we find that pulsars produce a flux of high-energy positrons that is similar in spectrum and magnitude to the positron fraction measured by PAMELA and AMS-02. In light of this result, we conclude that it is very likely that pulsars provide the dominant contribution to the long perplexing cosmic-ray positron excess. I will also discuss the implications of these results for pulsars in the Galactic Center region. Speaker: Prof. DAN HOOPER (Fermilab) • 3:15 PM CALET : Summary of the First Two-Year on Orbit 15m The CALorimetric Electron Telescope (CALET) space experiment, which has been developed by Japan in collaboration with Italy and the United States, is a high-energy astroparticle physics mission to be installed on the International Space Station (ISS). The primary goals of the CALET mission include investigating possible nearby sources of high energy electrons, studying the details of galactic particle propagation and searching for dark matter signatures. During a two-year mission, extendable to five years, the CALET experiment will be measureing the flux of cosmic-ray electrons (including positrons) to 20 TeV, gamma-rays to 10 TeV and nuclei with Z=1 to 40 up to 1,000 TeV. The instrument consists of two layers of segmented plastic scintillators for the cosmic-ray charge identification (CHD), a 3 radiation length thick tungsten-scintillating fiber imaging calorimeter (IMC) and a 27 radiation length thick lead-tungstate calorimeter (TASC). CALET has sufficient depth, imaging capabilities and excellent energy resolution to allow for a clear separation between hadrons and electrons and between charged particles and gamma rays. The instrument was launched on August 19,2015 to the ISS. Since the start of operation, a continuos observation has successfully being kept. We will have a summary of the CALET observation: 1) Electron energy spectrum, 2) Proton and Nuclei spectrum, 3) Gamma-ray observation, with results of the performance study on orbit. We also present the results of observations of the electromagnetic counterparts to LIGO-VIRGO gravitational wave events. Speaker: Yoichi Asaoka (Waseda University (JP)) • 2:00 PM 3:30 PM Cosmology Spartan Room (The Athenaeum) ### Spartan Room #### The Athenaeum Convener: Tom Giblin (Kenyon College) • 2:00 PM Sensitivity of cosmological data to the neutrino mass hierarchy 15m Present measurements are not able to firmly single out nature’s choice for the neutrino mass hierarchy. Consequently, in the absence of a robust measurement of the neutrino mass ordering, a desirable bound on the neutrino mass would be one which relies on the less informative possible assumption about the hierarchical distribution of the total mass among the three eigenstates. We will discuss a novel method to quantify the sensitivity of cosmological data to the neutrino mass hierarchy in the context of Bayesian analysis. Speaker: Martina Gerbino • 2:15 PM Cosmological Observables Beyond Linear Gravity 15m In recent years, advances in numerical methods have allowed us to calculate precision observables with fewer assumptions. Here I will discuss two of these observables, Hubble Diagrams and the Weak Lensing Convergence Power Spectrum. I will comment on the role that inhomogeneities, entering at high order, effects cosmological measurements. Speaker: Tom Giblin (Kenyon College) • 2:30 PM Primordial non-Gaussianity and statistical anisotropy 15m I will describe how statistical anisotropies, such as dipole modulations of the cosmic microwave background temperature and polarization fluctuations, are more likely if the primordial fluctuations are non-Gaussian. I will then discuss the implications of this effect for observations in the cosmic microwave background temperature and polarization anisotropies, and how such observations can be used to constrain the level of non-Gaussianities in the primordial fluctuations. In particular, I will focus on how the addition of statistical anisotropy information from E-mode polarization can help tighten current primordial non-Gaussianity constraints. Speaker: Saroj Adhikari (University of Michigan) • 2:45 PM CLUMPY: A public code for γ-ray and ν signals from Dark Matter structures 15m In this talk we will present the latest development of the CLUMPY code. The first version aimed at the calculation of the astrophysical J-factors from dark matter annihilation/decay in any galaxy or galaxy cluster dark matter halo including substructures. While refining on several aspects of the first version (halo-to-halo concentration scatter, multi-level boost factors, and triaxiality), the second release additionally provides i) a full refactoring of the I/O, ii) skymaps for γ-ray and ν fluxes from generic annihilation/decay spectra and the associated angular power spectrum, and iii) a Jeans analysis module to obtain dark matter density profiles and J-factors from kinematic data in relaxed spherical systems (e.g., dwarf spheroidal galaxies). After presenting some examples of these functionalities, we will also discuss the ongoing development of a third release that will include the overall extragalactic γ-ray flux from cosmic dark matter structure. Speaker: Moritz Hütten (DESY/Humboldt-Universität Berlin) • 3:00 PM Dark Matter Imprints of Heavy Long-Lived Particles 15m Particles present in the early Universe can leave observable imprints if they affect dark matter properties after dark matter has gone out of equilibrium with the thermal bath. We will investigate such possibilities and their associated observable signatures in several well-motivated dark matter frameworks. Speaker: Bibhushan Shakya (Cincinnati/Michigan) • 3:15 PM Searching for the Darkest Galaxies: Covering the Entire Southern Sky with DECam 15m Milky Way satellite dwarf galaxies are among the oldest, smallest, and most dark matter dominated galaxies in the known Universe. The study of these tiny galaxies can help shed light on the nature of dark matter and the mysteries of galaxy formation. Over the last two years, efforts using the Dark Energy Camera (DECam) have nearly doubled the known population of Milky Way satellite galaxies. However, to date, only a fraction of the southern sky has been uniformly imaged by DECam. We will present results from two new surveys, the Magellanic Satellites Survey (MagLiteS) and the Blanco Imaging of the Southern Sky (BLISS) survey, which are using DECam to image the southern sky to unprecedented depths. Speakers: Alex Drlica-Wagner (Fermilab), Keith Bechtol (LSST) • 2:00 PM 3:30 PM Dark matter Small Theater (The Athenaeum) ### Small Theater #### The Athenaeum Convener: Kerstin Perez (MIT) • 2:00 PM Improving the search for extragalactic dark matter using N-body simulations 15m Extragalactic galaxies and galaxy clusters are expected to be some of the brightest sources of dark matter annihilation on the sky. Further, catalogs such as the 2MASS survey, tell us where thousands of these objects are. The challenge, however, is that catalogs only detail a subset of the baryonic properties of these galaxies. In this talk I will outline how to map from a catalog of galaxies to map of the extragalactic dark matter distribution on the sky. I will show how the biases and systematics of the method can be understood in the context of an N-body simulation, and demonstrate that the projected sensitivity of this method at Fermi-LAT could produce limits comparable with those coming from the Milky Way Dwarfs. Speaker: Nicholas Rodd (Massachusetts Institute of Technology) • 2:15 PM A search for dark matter annihilation in nearby galaxy groups 15m We perform a search for dark matter (DM) annihilation in nearby galaxies using 413 weeks of publicly-available Fermi Pass 8 gamma-ray data, utilizing a novel method that takes advantage of recently-developed galaxy group catalogs based on the 2MASS Redshift Survey. Having validated our method using N-body simulations, we construct nearly all-sky maps of an expected DM annihilation signal in the local (z < 0.03) universe and look for this structure in the Fermi data, probing theoretically well-motivated regions of parameter space for conservative assumptions about substructure enhancement. I will present the results of our analysis, discussing the effect of modeling uncertainty and implications for the DM interpretation of the Galactic Center excess. Speaker: Siddharth Mishra Sharma (Princeton University) • 2:30 PM Searching for Dark Matter Annihilation in Milky Way Satellite Galaxies 15m Milky Way dwarf spheroidal satellite galaxies are the most dark-matter-dominated galaxies known. Due to their proximity, high dark matter content, and lack of astrophysical backgrounds, dwarf spheroidal galaxies are one of the most promising targets for the indirect detection of dark matter annihilation via gamma rays. Indeed, Fermi-LAT observations of previously known dwarf galaxies have robustly constrained the dark matter annihilation cross section to be less than the generic thermal relic cross section for dark matter particles with mass < 100 GeV. Recently, large optical surveys, such as the Dark Energy Survey and Pan-STARRS, have nearly doubled the known population of confirmed and candidate dwarf galaxies. We will present an updated gamma-ray analysis combining previously known and recently discovered dwarf galaxies, and discuss how current and future optical surveys will improve the sensitivity of gamma-ray searches for dark matter annihilation in dwarf galaxies. Speakers: Alex Drlica-Wagner (Fermilab), Keith Bechtol (LSST), Andrea Albert (Los Alamos National Lab) • 2:45 PM Sommerfeld-Enhanced J-Factors For Dwarf Spheroidal Galaxies 15m For models in which dark matter annihilation is Sommerfeld-enhanced, the annihilation cross section increases at low relative velocities. Dwarf spheroidal galaxies (dSphs) have low characteristic dark matter particle velocities and are thus ideal candidates to study such models. We model the dark matter phase space of dSphs as isotropic and spherically-symmetric and determine the$J$-factors for several of the most important targets for indirect dark matter searches. For Navarro-Frenk-White density profiles, we quantify the scatter in the$J$-factor arising from the astrophysical uncertainty in the dark matter potential. We show that, in Sommerfeld-enhanced models, the ordering of the most promising dSphs may be different relative to the standard case of velocity-independent cross sections. This result can have important implications for derived upper limits on the annihilation cross section, or on possible signals, from dSphs. Speaker: Kimberly Boddy (University of Hawaii) • 3:00 PM Investigating what the Milky Way's dwarfs have to tell us about the Galactic Center extended excess 15m The Milky Way's Galactic Center may harbor the signal of annihilating dark matter in a gamma-ray excess, though dwarf galaxies remain dark in their expected commensurate emission. We incorporate Milky Way dark matter halo profile uncertainties, as well as an accounting of diffuse gamma ray emission uncertainties in dark matter annihilation models for the Galactic Center Extended gamma-ray excess (GCE) detected by the Fermi Gamma Ray Space Telescope. The range of particle annihilation rate and masses expand when including these unknowns. However, two of the most precise empirical determinations of the Milky Way halo's local density and density profile leave the signal region to be in considerable tension with dark matter annihilation searches from combined dwarf galaxy analyses for single-channel dark matter annihilation models. Accordingly, we quantify this tension in a joint likelihood analysis. We also show that astrophysical models and a representative self-interacting dark matter model avoid the tensions between the GCE signal and lack of a signal from the dwarfs. Since these arguments disfavor the intepretation of the GCE as prompt annihilation of dark matter, we set limits on the cross section for that process. Speaker: Ryan Keeley (UC, Irvine) • 3:15 PM Searching for dark matter annihilation in Galactic substructure with photon statistics 15m We propose a novel method to search for signatures of dark matter annihilation in Galactic substructure using gamma-ray data from the$\it Fermi$Large Area Telescope. The method takes advantage of the fundamentally different photon-count statistics that describe dark matter annihilation from a population of subhalos versus from the smooth Milky Way halo. In addition, it exploits differences in the spatial distribution of subhalos and other astrophysical populations to improve the sensitivity to the substructure signature. We apply this analysis method to simulated$\it Fermidata and derive the projected sensitivity to dark matter annihilation in substructure. We can probe theoretically well-motivated regions of parameter space, providing a complementary method to existing dark matter searches. Speaker: Laura Chang (Princeton University) • 2:00 PM 3:30 PM Gamma rays Corinthian Room (The Athenaeum) ### Corinthian Room #### The Athenaeum Convener: Yoshiyuki Inoue (ISAS/JAXA) • 2:00 PM EBL constraints using TeV blazars observed with the MAGIC telescopes 15m Recent results on the Extragalactic Background Light (EBL) intensity obtained from a combined likelihood analysis of blazar spectra detected by the MAGIC telescopes are reported. The EBL is the optical-infrared diffuse background light accumulated during galaxy evolution, directly and/or reprocessed by dust, which provides unique information about the history of galaxy formation. The low energy photons from the EBL may interact with very high energy (VHE, E > 100 GeV) photons from blazars, which are a subclass of Active Galactic Nuclei whose relativistic jets point towards Earth. This interaction between the EBL and the gamma-ray photons leaves an energy-dependent imprint of the EBL on the VHE gamma-ray spectra of the blazars. Therefore, the study of their spectra can be used to constrain the EBL density at different wavelengths and its evolution in time. The MAGIC telescopes are a stereoscopic system of two Imaging Atmospheric Cherenkov Telescopes of 17 m diameter each, situated in La Palma, Spain, and sensitive to gamma-ray photons with energies larger than about 50 GeV. In the last few years the MAGIC telescopes obtained accurate measurements of the spectra of 12 blazars in the redshift range from z=0.03 to z=0.944 for over 300 hours of observation. This allows us to improve upon previous constraints on EBL by MAGIC, compatible with the state-of-the-art EBL models. Speaker: Gaia Vanzo (Instituto de Astrofísica de Canarias) • 2:15 PM Determining the Intergalactic Photon Densities from Deep Galaxy Surveys and the Gamma-ray Opacity of the Universe 15m We have calculated the extragalactic IR-UV photon density as a function of redshift, and the resulting IR-UV spectrum of the extragalactic background light. Our empirically-based approach is based on local-to-deep galaxy survey data obtained in different wavelength bands using many space-based telescopes. This approach allowed us, for the first time, to obtain a completely model independent determination of extragalactic photon densities, and also to quantify their uncertainties. Using our photon density results, we were able to place 68% confidence upper and lower limits on the opacity of the universe to gamma-rays as a function of energy and redshift. We compared our results with Fermi analyses of the spectra of extragalactic gamma-ray sources. Speaker: Floyd Stecker (NASA Goddard Space Flight Center) • 2:30 PM Time dependence of AGN pair echo, and halo emission as a probe of weak extragalactic magnetic fields 15m Gamma-rays with energy exceeding 100 GeV emitted by extragalactic sources initiate cascades in the intergalactic medium. The angular and temporal distribution of the cascade photons that arrive at the Earth depend on the strength and configuration of extragalactic magnetic fields in the line of sight. For weak enough fields, extended emission around the source (halo) is expected to be detectable, and the characteristics (angular size, energy dependence, and shape) of this emission are a sensitive probe of EGMF strength and correlation length. We model the expected specta and angular profiles of blazars, and misaligned active galactic nuclei (radio-galaxies) in a wide range of parameter space of the extra-galactic magnetic field strength and correlation length, which is unconstrained by existing measurements. Our calculations focus on the time dependence of such halo emission, which is being discussed for the first time in this work. We present the competitive bounds on/measurement of the extragalactic magnetic field strength and correlation length that are implied by the absence/detection of such, extended emission, in stacked searches of GeV halo emission by blazars, and radio-galaxies. Speaker: Foteini Oikonomou (Penn State University) • 2:45 PM Searches for Angular Extension in High Latitude Fermi-LAT Sources 15m We report on the Fermi High-Latitude Extended Source Catalog (FHES), a systematic search for spatial extension of gamma-ray point sources detected with the Fermi Large Area Telescope (LAT) at Galactic latitudes |b| > 5 degrees. Point sources listed in the 3FGL and 3FHL catalogs are used for this search. While the majority of high-latitude LAT sources are extragalactic blazars that appear point-like within the LAT angular resolution, there are several physics scenarios that predict the existence of populations of spatially extended sources. If dark matter consists of weakly interacting massive particles, the annihilation or decay of these particles in subhalos of the Milky Way would appear as a population of unassociated gamma-ray sources with finite angular extent. Gamma-ray emission from blazars could also be extended (so-called pair halos) due to the deflection of electron-positron pairs in the intergalactic magnetic field (IGMF). The pairs are produced in the absorption of gamma rays in the intergalactic medium and subsequently up-scatter photons of background radiation fields to gamma-ray energies. The measurement of pair halos would constrain the strength and coherence length scale of the IGMF. We report on new extended source candidates and their associations found in the FHES as well as limits on the IGMF based on the non-observation of the cascade. Speaker: Manuel Meyer (Stanford University) • 3:00 PM Probing extragalactic magnetic fields with the gamma-ray spectrum of PG 1553+113 15m The very high energy (E > 100 $GeV) gamma-ray flux from extragalactic sources is attenuated due to$e^+e^-$pair production on the extragalactic background light (EBL). This attenuation process can lead to the development of electromagnetic cascades from the inverse-Compton scattering of background photons by the produced$e^+e^-$pairs. The cascade secondary gamma-ray emission is reprocessed at lower energies and its spectral and temporal behavior depends on the properties of the extragalactic magnetic field (EGMF) along the line of sight due to the deflections of the charged component of the cascade. The temporal and spectral energy distribution structure of the gamma-ray emission from blazars can then be used to probe the EGMF. In this contribution the gamma-ray blazar PG 1553+113 is identified as a promising target to search for secondary emission, based on H.E.S.S. and Fermi-LAT energy spectra. Monte-Carlo simulations of cascades using the public code ELMAG are performed to derive EGMF constraints under different assumptions on the intrinsic spectrum and the time span of the gamma-ray activity of the source. Prospects to take advantage of the quasi-periodic modulation seen in the activity of PG 1553+113 to look for secondary gamma-ray emission are also presented. Speaker: Matthias Lorentz (IRFU - CEA Saclay) • 3:15 PM Probing faint gamma-ray point sources in the inner Milky Way using PCAT 15m Poisson regression of the Fermi-LAT data in the inner Milky Way reveals an extended gamma-ray excess. An important question is whether the signal is coming from a collection of unresolved point sources, possibly old recycled pulsars, or constitutes a truly diffuse emission component. Previous analyses have relied on non-Poissonian template fits or wavelet decomposition of the Fermi-LAT data, which find evidence for a population of faint point sources just below the 3FGL flux limit. In order to test this hypothesis, we use a Bayesian, transdimensional, and hierarchical inference framework, PCAT (Probabilistic Cataloger), by sampling from the posterior catalog space of faint point sources consistent with the observed gamma-ray emission in the inner Milky Way. By marginalizing over faint point sources, we constrain their spatial and spectral distributions. We then compare the performance of probabilistic cataloging with that of fluctuation analysis when inferring unresolved point sources in the low signal-to-noise limit. Speaker: Tansu Daylan (Harvard University) • 2:00 PM 3:30 PM Multi-messenger Athenian Room (The Athenaeum) ### Athenian Room #### The Athenaeum Convener: Kohta Murase (Penn State University) • 2:00 PM Astronomy's "Next Big Thing:" What can we expect from direct gravitational-wave observations? 30m Advanced LIGO's ongoing observation runs provided humanity with the first direct detection of gravitational waves, just in time for the 100th anniversary of Einstein's prediction. Beyond the discovery, there is a growing focus on incorporating gravitational waves as a new window on questions from violent transients to cosmology. I will discuss some aspects of (i) the instrumental breakthroughs that enabled the unprecedented sensitivity reached by Advanced LIGO and (ii) the key scientific directions in which gravitational wave searches can be utilized, directly as well as in the context of multimessenger astronomy. Speaker: Prof. Szabolcs Marka (Columbia University in the City of New York) • 2:30 PM A "nu" look at gravitational waves: The black hole birth rate from neutrinos combined with the merger rate from LIGO 15m I present my recent paper arXiv:1704.05073 on making projections for measuring the black hole birth rate from the diffuse supernova neutrino background (DSNB) by future neutrino experiments, and the information which can be gained by combining this with the merger rate from LIGO. The DSNB originates from neutrinos emitted by all the supernovae in the Universe, and is expected to be made up of two components: neutrinos from neutron-star-forming supernovae, and a sub-dominant component at higher energies from black-hole-forming "unnovae". We perform a Markov Chain Monte Carlo analysis of simulated data of the DSNB in an experiment similar to Hyper Kamiokande, focusing on this second component. Since the only evidence for unnovae comes from simulations of collapsing stars, we choose two sets of priors: one where the unnovae are well-understood and one where their neutrino emission is poorly known. By combining the black hole birth rate from the DSNB with projected measurements of the black hole merger rate from LIGO, we show that the fraction of black holes which lead to binary mergers observed today ϵ could be constrained to be within the range 8⋅10^−4≤ϵ≤5⋅10^−3, after ten years of running an experiment like Hyper Kamiokande. Speaker: Dr Jonathan Davis (King's College London) • 2:45 PM Gravitational waves from bubble dynamics: Beyond the Envelope 15m We study gravitational wave (GW) production from bubble dynamics during a cosmic first-order phase transition by using the method of relating the GW spectrum to the two-point correlation function of the energy-momentum tensor < T(x) T(y) >. We adopt the thin-wall approximation but not the envelope approximation, and take the (long-lasting) non-envelope parts into account by assuming free propagation after collision. We first write down the analytic expressions for the spectrum, and then evaluate them with numerical methods. As a result, the growth and saturation of the spectrum are observed as a function of the duration time of the non-envelope parts. It is found that the IR region of the spectrum shows a significant enhancement compared to the one with the envelope approximation, growing from$f^3$to$f^1$in the long-lasting limit. In addition, we find saturation in the spectrum in the same limit, indicating a decrease in the correlation of the energy-momentum tensor at late times. Our results are relevant to GW production from bubble collisions and sound waves. Speaker: Masahiro Takimoto (Weizmann Institute of Science) • 3:00 PM Neutron star mergers and multi-messenger astronomy 30m With the discovery of binary black hole mergers by LIGO, the era of gravitational wave (GW) astronomy and multi-messenger astronomy including GWs has begun. As the advanced LIGO and Virgo detectors approach design sensitivity in the next few years, exciting discoveries are expected to be made, including neutron star mergers, which are among the most promising GW events for multi-messenger astronomy. In this talk, I will present recent results from general-relativistic magnetohydrodynamic simulations of the merger and long-term post-merger evolution, and discuss how multi-messenger observations of NS mergers may represent the key to understand and solve several long-standing problems in astrophysics; these include the origin and generation of GWs and accompanied electromagnetic transients across the electromagnetic spectrum including short gamma-ray bursts and kilonovae, the properties of nuclear matter at high densities, and the origin of the heavy elements in the universe. Speaker: Dr Daniel Siegel • 3:30 PM 4:00 PM Coffee break 30m Oak Room (The Athenaeum) ### Oak Room #### The Athenaeum • 4:00 PM 5:00 PM Cosmic rays Macedonian Room (The Athenaeum) ### Macedonian Room #### The Athenaeum Convener: nahee park (University of Chicago) • 4:00 PM Recent results from the Pierre Auger Observatory 15m The objectives of the Pierre Auger Observatory are to probe the origin and characteristics of cosmic rays above$10^{17}$eV and to study the interactions of these, the most energetic particles observed in nature. The Observatory design features an array of water Cherenkov stations deployed over a surface of$3000$km$^2$overlooked by fluorescence telescopes. This design and a sophisticated data analysis pipeline provide us with a large set of high quality data, which has led to major breakthroughs in the last decade. The Observatory has recorded data from an exposure exceeding$60,000$km$^2$sr yr since its beginning in 2004. The latest results together with systematic uncertainties are discussed in this talk. A major upgrade, known as AugerPrime, with an emphasis on improved mass composition determination using the surface detector is also presented. Speaker: Dr Radomir Smida (Karlsruhe Institute of Technology) • 4:15 PM Recent results from the Telescope Array Experiment 15m The Telescope Array (TA) measures the properties of ultra high energy cosmic ray (UHECR) induced extensive air showers. TA employs a hybrid detector comprised of a large surface array of scintillator detectors overlooked by three fluorescence telescopes stations. The TA Low Energy extension (TALE) detector has operated as a monocular Cherenkov/fluorescence detector for nearly three years, and has just been complemented by a closely spaced surface array to commence data taking in hybrid mode. The TAx4 upgrade is underway and aims to, as the name suggests, quadruple the size of the surface array to improve statistics at the highest energies (post-GZK events). status of In this talk we will describe the experiment and it's various upgrades, and we will summarize the latest results on the energy spectrum, composition, and anisotropy of UHECR, obtained with nine years of observation. The energy spectrum measured by the TALE FD, extending from a low energy of 4 PeV to a high of few EeV, will be presented in some detail. Speaker: Dr Tareq AbuZayyad (University of Utah) • 4:30 PM The cosmic ray flux spectrum above 300 PeV of the Pierre Auger Observatory 15m The flux of cosmic rays is observed at the Pierre Auger Observatory spanning almost three decades in energy. This energy range is possible by combining the measurements from the nested 1500 m and 750 m surface detector arrays. The energy scale relies on the almost calorimetric energy measurements performed with Auger's fluorescence detectors. With a total exposure of about 52000 [km^2 sr yr] the observatory has accumulated large statistics which allows for a precise measurement of the flux spectrum above 300 PeV. A spectral shape, motivated by potential cosmic ray source models, is used to identify the spectral features including the ankle and the suppression at the highest energies. The shape of the spectrum is discussed along with its implications. Speaker: Alan Coleman (Penn State University) • 4:45 PM First results from the full-scale prototype for the Fluorescence detector Array of Single-pixel Telescopes 15m The Fluorescence detector Array of Single-pixel Telescopes (FAST) is a design concept for the next generation of Ultra-High-Energy Cosmic Ray (UHECR) observatories, addressing the requirements for a large-area, low-cost detector suitable for measuring the properties of the highest energy cosmic rays. In the FAST design, a large field of view is covered by a few pixels at the focal plane of an optical apparatus. Motivated by the successful detection of UHECRs using a prototype comprised of a single 200 mm PMT and a 1 square meter Fresnel lens system, we have developed a new full-scale prototype consisting offour 200 mm PMTs at the focus of a 1.6m segmented mirror. In October 2016 we installed the full-scale prototype at the Telescope Array site in central Utah, USA, and began steady data acquisition. We report on first results of the full-scale FAST prototype, including measurements of artificial light sources, distant ultraviolet lasers, and UHECRs. Speaker: John Farmer (University of Chicago) • 4:00 PM 5:00 PM Cosmology Spartan Room (The Athenaeum) ### Spartan Room #### The Athenaeum Convener: Tom Giblin (Kenyon College) • 4:00 PM Science with the Hyper Suprime-Cam Survey 30m The WFIRST high-latitude survey (HLS) will provide an exciting dataset for constraining dark energy through a variety of measurement methods. In this talk, I will describe the current plans for the WFIRST HLS and the potential for competitive constraints on dark energy with weak lensing. I will also discuss the potential synergies with other surveys during the same time-frame, including the opportunities provided by joint analysis with LSST, Euclid, and CMB-S4. Finally, I will present the results of ongoing efforts to understand the impact of near-infrared detector systematics on weak lensing measurements, and to place requirements on the hardware to ensure that the scientific goals of the survey can be met. Speaker: Rachel Mandelbaum (Carnegie Mellon University) • 4:30 PM Maximizing Information-Extraction from Next-Generation Surveys 15m I will present a suite of new algorithms for measuring higher-point statistics from large-scale structure surveys. I will begin with a transformatively-fast algorithm that enables computation of the isotropic 3-point correlation function scaling as the number of galaxies squared. This algorithm was applied to BOSS data to make the first high-significance detection of the Baryon Acoustic Oscillations as well as to constrain novel forms of biasing. I will then present a generalization of the algorithm allowing computation of the anisotropic 3PCF. I'll close by showing how the fundamental kernel of these algorithms enables measurement of N-point functions for any desired N scaling as the square of the number of galaxies. Speaker: Dr Zachary Slepian (LBNL) • 4:45 PM Failures of homogeneous and isotropic cosmologies in Extended Quasi-Dilaton Massive Gravity 15m We analyze the Extended Quasi-Dilaton Massive Gravity model around a Friedmann-Lemaitre-Robertson-Walker cosmological background. We present a careful stability analysis of asymptotic fixed points. We find that the traditional fixed point cannot be approached dynamically, except from a perfectly fine-tuned initial condition involving both the quasi-dilaton and the Hubble parameter. A less-well examined fixed-point solution, where the time derivative of the 0-th Stuckelberg field vanishes$\dot\phi^0=0$, encounters no such difficulty, and the fixed point is an attractor in some finite region of initial conditions. We examine the question of the presence of a Boulware-Deser ghost in the theory. We show that the additional constraint which generically allows for the elimination of the Boulware-Deser mode is$\textit{only}$present under special initial conditions. We find that the only possibility corresponds to the traditional fixed point, and the initial conditions are the same fine-tuned conditions that allow the fixed point to be approached dynamically. Statement of Acknowledgement: This presentation was made possible, in part, through financial support from the School of Graduate Studies at Case Western Reserve University. Speaker: Mr Saurabh Kumar (Case Western Reserve University) • 4:00 PM 5:00 PM Dark matter Small Theater (The Athenaeum) ### Small Theater #### The Athenaeum Convener: Benjamin Safdi (massachusetts institute of technology) • 4:00 PM LD2DM scenario as an explanation of the AMS-02 positron excess 15m In this talk, we discuss a scenario called late-decaying two-component dark matter (LD2DM), where the entire DM consists of two semi-degenerate species. Within this framework, the heavier species is produced as a thermal relic in the early universe and decays to the lighter species over cosmological timescales. Consequently, the lighter species becomes the DM which populates the universe today. We show that annihilation of the lighter DM species with an enhanced cross-section, produced via such a non-thermal mechanism, can explain the observed excess in AMS-02 positron flux while avoiding CMB constraints from the recombination epoch. We demonstrate that the scenario is robust, subject to constraints from structure formation and CMB constraints on late-time energy depositions during the cosmic dark ages. We explore possible cosmological and particle physics signatures in a toy model that realizes this scenario. Speaker: Jatan Buch (Brown University) • 4:15 PM Zero-Range Effective Field Theory for Resonant Wino Dark Matter 15m The most dramatic "Sommerfeld enhancements'' of neutral-wino-pair annihilation occur when the wino mass is near a critical value where there is a zero-energy S-wave resonance at the neutral-wino-pair threshold. Near a critical mass, low-energy winos can be described by a zero-range effective field theory in which the winos interact nonperturbatively through a contact interaction. The effective field theory is controlled by a renormalization-group fixed point at which the neutral and charged winos are degenerate in mass and their scattering length is infinite. The parameters of the zero-range effective field theory can be determined by matching wino-wino scattering amplitudes calculated by solving the Schrödinger equation for winos interacting through a potential due to the exchange of weak gauge bosons. If the wino mass is larger than the critical value, the resonance is a wino-pair bound state. The power of the zero-range effective field theory is illustrated by calculating the rate for formation of the bound state in the collision of two neutral winos through the emission of two soft photons. Speaker: Evan Johnson (Ohio State University) • 4:30 PM Thermal Dark Matter Below an MeV 15m In this talk, I will discuss a class of models in which thermal dark matter is lighter than an MeV. If dark matter thermalizes with the Standard Model below the temperature of neutrino-photon decoupling, constraints from measurements of the effective number of neutrino species are alleviated. This framework motivates new experiments in the direct search for sub-MeV thermal dark matter and light force carriers. Speaker: Asher Berlin (University of Chicago) • 4:45 PM Indirect Detection of Neutrino Portal Dark Matter 15m We investigate the feasibility of the indirect detection of dark matter in a simple model using the neutrino portal. The model is very economical, with right-handed neutrinos generating neutrino masses through the Type-I seesaw mechanism and simultaneously mediating interactions with dark matter. Given the small neutrino Yukawa couplings expected in a Type-I seesaw, direct detection and accelerator probes of dark matter in this scenario are challenging. However, dark matter can efficiently annihilate to right-handed neutrinos, which then decay via active-sterile mixing through the weak interactions, leading to a variety of indirect astronomical signatures. We derive the existing constraints on this scenario from Planck cosmic microwave background measurements, Fermi dwarf spheroidal galaxies and Galactic Center gamma-rays observations, and AMS-02 antiprotons observations, and also discuss the future prospects of Fermi and the Cherenkov Telescope Array. Thermal annihilation rates are already being probed for dark matter lighter than about 50 GeV, and this can be extended to dark matter masses of 100 GeV and beyond in the future. This scenario can also provide a dark matter interpretation of the Fermi Galactic Center gamma ray excess, and we confront this interpretation with other indirect constraints. Finally we discuss some of the exciting implications of extensions of the minimal model with large neutrino Yukawa couplings and Higgs portal couplings. Speaker: Barmak Shams Es Haghi (University of Pittsburgh) • 4:00 PM 5:00 PM Gamma rays Corinthian Room (The Athenaeum) ### Corinthian Room #### The Athenaeum Convener: Yoshiyuki Inoue (ISAS/JAXA) • 4:00 PM SkyFACT: a novel analysis of Fermi diffuse gamma-ray data 15m All models for Galactic diffuse gamma-ray emission share one property: They give formally a remarkably bad fit to the data. A large number of statistically significant residuals remain, making it very challenging to discriminate genuine features in the data from analysis artefacts. We present SkyFACT (Sky Factorization with Adaptive Constrained Templates) [1], a new approach for studying, modeling and decomposing diffuse gamma-ray emission. In contrast to previous approaches, we can account for fine-grained variations related to uncertainties in gas tracers and small scale variations in the cosmic-ray density, that are missed in predictions from cosmic-ray propagation codes, by introducing (and handling) ~100,000 nuisance parameters. We combine methods of image reconstruction and adaptive spatio-spectral template regression in one coherent hybrid approach. We apply the method to the gamma-ray emission from the inner Galaxy, as observed by the Fermi Large Area Telescope. We define a simple reference model that removes most of the residual emission from the inner Galaxy and characterize extended emission components: the Fermi bubbles, the Fermi Galactic center excess, and extended sources along the Galactic disk. [1] E.Storm, C. Weniger and F. Calore, arXiv:1705.04065 [astro-ph.HE], Submitted to JCAP. Speaker: Francesca Calore (LAPTh, CNRS) • 4:15 PM Measuring High-Energy Gamma-Ray Spectra with HAWC 15m The High-Altitude Water-Cherenkov (HAWC) experiment is a TeV gamma-ray observatory located at 4100 m above sea level on the Sierra Negra mountain in Puebla, Mexico. Each of the detector's 300 water-filled tanks is instrumented with four photomultiplier tubes that detect the Cherenkov radiation produced by charged particles created in extensive air showers. With an instantaneous field of view of 2 sr and a duty cycle exceeding 95%, HAWC is a powerful survey instrument sensitive to pulsar wind nebulae, supernova remnants, active galactic nuclei, and other gamma-ray sources. The mechanisms of particle acceleration at these sites can be probed by measuring their emitted photon energy spectra. To this end, we have developed an event-by-event method for reconstructing the energies of HAWC gamma-ray events using an artificial neural network. We will show that this new technique greatly improves HAWC's energy resolution and enables it to precisely resolve energies as high as 100 TeV in Monte Carlo. We will also present the progress towards measuring high-energy spectra with the new energy-estimation method. Speaker: Mr Samuel Marinelli (Michigan State University) • 4:30 PM A Hadronic Model of the Fermi Bubbles: Galactic Cosmic-Rays in a Breeze 15m We present a self-consistent model of the Fermi Bubbles, described as a decelerating outflow of gas and non-thermal particles produced within the Galactic center region, on a$\sim 100$Myr timescale. Motivated by observations, we use an outflow with velocity O(100 km/s), which is slower than the velocities used in models describing the Bubbles as a more recent outburst. We take into account cosmic-ray (CR) energy losses due to proton-proton interactions, and calculate the resulting gamma-ray emission. Our model can reproduce both the spatial morphology and the spectra of the Bubbles, on a range of different scales. We find that CRs diffusing and advecting within a breeze outflow result in an approximately flat surface brightness profile of the gamma-ray emission, as observed by Fermi satellite. Finally, we apply similar outflow profiles to larger Galactocentric radii, and investigate their effects on the CR spectrum and boron-to-carbon ratio. Hardenings can appear in the spectrum, even in cases with equal CR diffusion coefficients in the disk and halo. It is postulated that this hardening effect may relate to the observed hardening feature in the CR spectrum at a rigidity of$\sim 200$GV. I am also submitting an abstract to the tracks "cosmic rays" and "Galactic sources". Speaker: Gwenael Giacinti (MPIK Heidelberg) • 4:45 PM Radio and Gamma-Ray Constraints on the Wind, Magnetic Field, and Cosmic Rays along the minor axis of the starburst M82 15m Cosmic rays can be probed by their non thermal emission in the radio and in gamma-ray bands. One-zone models of cosmic rays have been used to match the integrated emission of starburst galaxies. We construct multi-dimensional models of the local starburst M82 using cosmic ray propagation code GALPROP. Using the integrated gamma-ray and radio spectra, along with the vertical distribution of radio emission along the minor axis, we constrain the gas density, magnetic field strength, and cosmic ray population. We show that the wind velocity and diffusion coefficient can be constrained by the morphology of the radio halo. We discuss the interplay between gas density, magnetic field, and outflow velocity and how they effect the emission. We comment on the energetics of cosmic ray species in the system. We provide direct constraints on the dynamical importance of cosmic rays in driving the outflow of the galaxy. Speaker: Benjamin Buckman (The Ohio State University) • 4:00 PM 5:00 PM Multi-messenger Athenian Room (The Athenaeum) ### Athenian Room #### The Athenaeum Convener: Amanda Weinstein (Iowa State University) • 4:00 PM The Present and Future of Real-Time Alerts from AMON 15m The Astrophysical Multimessenger Observatory Network (AMON), will connect observatories from around the world, enabling real-time coincidence searches of all four messengers (neutrinos, cosmic rays, gamma rays, and gravitational waves) and rapid follow-up observations of these alerts. AMON’s first real-time alerts were commissioned in 2016 with “pass-through” notices of IceCube likely-cosmic (HESE and EHE type) neutrino events, leading to multiple follow-up campaigns which have been reported through the GCN circulars. Looking ahead, AMON's first bona-fide multimessenger real-time alerts are planned to be high-energy neutrino + gamma-ray (“nu + gamma”) alerts resulting from coincidence of IceCube neutrinos and Swift, Fermi, or High-Altitude Water Cherenkov (HAWC) gamma-ray transients or subthreshold signals. The talk will summarize key properties of current alert streams and preview the expected properties of upcoming nu+gamma AMON Alerts. Speaker: James DeLaunay (Penn State) • 4:15 PM Search for High-energy Neutrino Emission from Fast Radio Bursts 15m Fast radio bursts (FRBs) are non-periodic millisecond radio outbursts that are thought to be of astrophysical origin. Since the first FRB was discovered by the Parkes Radio Telescope in 2007, a total of 23 FRBs with unique locations (FRB 121102 has repeated dozens of times) have been observed to date, with multiple radio telescopes. Although the nature of the FRBs is still largely unknown, the high dispersion measures of the FRBs indicate that they are most likely originating from extragalactic sources. A large multitude of models have been proposed to explain the FRB phenomena, most of which involve strong magnetic fields and are of leptonic nature. Currently, there are no concrete models predicting high-energy neutrinos from FRBs, while in principle a strongly magnetized environment such as that from a magnetar could produce short radio bursts due to the volatility of the magnetic fields, and having hadronic processes present at the same time. We will present the results from a recent search for high-energy neutrinos coincident spatially and temporally with FRBs in 6 years of IceCube data. Speaker: Donglian Xu (University of Wisconsin-Madison) • 4:30 PM An FRB in a bottle? : A multi-wavelengh approach 15m Recently a repeating fast radio burst (FRB) 121102 has been confirmed to be an extragalactic event and a persistent radio counterpart has been identified. One of the leading models is the young neutron star model, in which a pulsar (or magnetar) of$\leq$100 yrs-old surrounded by a wind nebula and supernova remnant are considered and connections between FRBs and luminous pulsar-driven supernovae are predicted. I will discuss multi-messenger/multi-wavelength approaches to testing the scenario. Speaker: Kazumi Kashiyama • 4:45 PM Seeking the sources of high-energy neutrinos with Swift 15m IceCube has reported discovery of the first high-energy astrophysical neutrino candidates, however the nature of the sources responsible for these neutrinos - potentially also the sources of the highest-energy cosmic rays - is still unknown and no high-confidence electromagnetic counterparts to any of the neutrino events have yet been detected. If the sources producing these highest-energy cosmic neutrinos are transient, they may be identifiable in rapid-response observations at Swift. The possibility of discovering multimessenger transient sources in this fashion is one of the main motivations for the Astrophysical Multimessenger Observatory Network (AMON). I will present the results of the first Swift satellite follow-up campaigns seeking to identify transient or variable X-ray or UV/optical sources that might be associated with the high-energy neutrinos detected by the IceCube Neutrino Observatory. Real-time public alerts providing coordinates and arrival times of high-energy neutrino events have been provided by IceCube and distributed via AMON and Gamma-Ray Coordinates Network (GCN) since April 2016. Speaker: Azadeh Keivani • 6:00 PM 10:00 PM Conference dinner Columbus Museum of Art #### Columbus Museum of Art 480 E Broad St, Columbus, OH 43215 • Thursday, August 10 • 9:00 AM 12:06 PM Plenary session Davidson Theatre #### Davidson Theatre Conveners: Dr Katie Auchettl (Center for Cosmology and Astroparticle Physics, The Ohio State University), Tim Linden • 9:00 AM High-energy x-rays 30m Speaker: Fiona Harrison • 9:30 AM High-energy emission from compact astrophysical objects 30m Compact astrophysical sources represent the most extreme and powerful end-points of the life of massive stars. They power relativistic and magnetized plasma which interact with the ambient medium, leading to a large variety of phenomena observable in the high- and very-high energy regime. In particular the complex Pulsar/Pulsar Wind-Nebulae/Supernova Remnant blast provides an optimal scenario to study fundamental questions on plasma-magnetic field interactions, covering a wide range of dimension and acceleration regime scales, ranging from a few kilometres to more than 20 pc in some cases, and from a few thousands of kilometres per second to relativist velocities. We will review the most recent experimental results concerning this kind of objects and the implications in our current knowledge of the physics processes behind the observed radiation. Speaker: Dr Emma de Ona Wilhelmi (CSIC-IEEC) • 10:00 AM Coffee break 30m Davidson Theatre #### Davidson Theatre • 10:30 AM The Multi-TeV Northern sky seen with HAWC 30m I will present the most recent results from two years of HAWC data. Speaker: Prof. Miguel Mostafa (Penn State University) • 11:00 AM The Search of Dark Matter in the Gamma Ray Sky 30m The annihilation of dark matter can lead to observable signatures in high-energy gamma rays. I will review the current status of such dark matter searches with data from the Fermi Large Area Telescope. In particular, I will discuss searches within the Milky Way and Local Group, and present results from a new study that uses galaxy surveys to improve sensitivity to signals of extragalactic dark matter. Speaker: Prof. Mariangela Lisanti (Princeton Univetsity) • 11:30 AM Recent Updates on the 3.5 keV Line 18m A well-motivated warm dark matter candidate, sterile neutrinos, can radiatively decay and emit X-rays detectable in observations of large dark matter aggregations such as galaxies and clusters of galaxies. I will review the current and past efforts on searching for decaying dark matter in galaxy clusters and galaxies with a special focus on the 3.5 keV line. Additionally, I will summarize how the recent constraints can be improved using the future X-ray observations. Speaker: Esra Bulbul • 11:48 AM Resolving High Energy Universe Using Strong Gravitational Lensing 18m Extragalactic jets are the largest particle accelerators in the universe, producing radiation ranging from radio wavelengths up to very high-energy gamma rays. Spatial origin of gamma-ray radiation from these sources cannot be fathom due to the poor angular resolution of the detectors. We propose to investigate gravitationally lensed blazars. Cosmic lenses magnify the emission and produce time delays between mirage images. These time delays depend on the position of the emitting regions in the source plane. We combine the precisely measured time delays at gamma rays, well-resolved positions of radio images, a model of the lens and the Hubble constant to elucidate the origin of gamma-ray flares from bright blazar B2 0218+35. With this approach, we achieve 1 milliarcsecond spatial resolution of the source at gamma-ray energies. We find that the gamma-ray flares do not originate from the radio core as commonly assumed. Speaker: Anna Barnacka (Harvard University) • 12:06 PM 2:00 PM Lunch 1h 54m • 2:00 PM 3:30 PM Cosmic rays Macedonian Room (The Athenaeum) ### Macedonian Room #### The Athenaeum Convener: Michael Sutherland • 2:00 PM Radio detection of cosmic rays - achievements and opportunities 30m Over the last 15 years, we have achieved a detailed understanding of the physics of radio emission from extensive air showers, and have consequently succeeded in developing sophisticated detection schemes and analysis approaches. In particular, we have demonstrated that the important air-shower parameters arrival direction, particle energy and depth of shower maximum can be reconstructed reliably from radio measurements, with both precision and accuracy comparable with those of other detection techniques. In this talk I will review the achievements of the radio detection technique and discuss the potential for future application in existing and new experiments for cosmic-ray detection. Speaker: Tim Huege (KIT) • 2:30 PM Results of the TREND experiment 15m We demonstrate here the ability of TREND, a self-triggered radio array, to autonomously detect and identify air showers induced by cosmic rays. TREND (Tianshan Radio Experiment for Neutrino Detection) is an array of 50 dipolar antennas, deployed over a total area of 1.5km² on the site of the 21CMA radio interferometer in the radio-quiet Tianshan mountains (China), and running between 2009 and 2014. TREND DAQ system was designed to allow for a trigger rate up to 200Hz per antenna, based on a very basic signal-over-threshold trigger condition. The reconstruction and discrimination of air showers from the ultra-dominant background noise is then performed through an offline treatment. We present here, for the first time, the complete analysis of the TREND data. We first detail the background-rejection algorithm which allowed to select about 500 air shower radio candidates from the ~10^9 radio pulses recorded with the TREND array. We then show that the distribution of the directions of arrivals of these 500 candidates is compatible with what is expected for air showers. We finaly compute the TREND air shower detection efficiency, thanks to an end-to-end simulation chain which will be detailed here. Given the fairly basic TREND acquisition chain, these results can be considered extremely encouraging in the perspective of future experiments using radio as a way to detect air showers, such as the Giant Radio Array for Neutrino Detection. Speaker: Olivier Martineau (CNRS) • 2:45 PM Observations of the Very Local Interstellar Medium with the IBEX and Voyager Spacecraft 15m The Interstellar Boundary Explorer (IBEX) is an Earth-orbiting spacecraft equipped with two single-pixel cameras that detect neutral atoms produced by the interaction of the solar wind (SW) with the very local interstellar medium (VLISM), as well as neutral atoms flowing in from the VLISM itself. After its launch in 2009, IBEX discovered the unexpected existence of the “ribbon,” a nearly circular arc of enhanced hydrogen ENA flux at ~keV energies. The enhanced ribbon fluxes are believed to originate from look directions perpendicular to the local interstellar magnetic field draped around the heliosphere. A comparative analysis of ribbon flux simulations with IBEX data derived a “pristine” interstellar field strength of ~3 μG just beyond the influence of the heliosphere, directed towards ~(26°, 50°) in galactic longitude/latitude. IBEX observations complement the only in situ observations of the VLISM made by the Voyager 1 spacecraft. Since crossing the heliopause in August 2012, Voyager 1 has been measuring the VLISM plasma properties, including the galactic cosmic ray flux, (indirectly) the compressed interstellar plasma density, as well as the interstellar magnetic field draped around the heliosphere. This talk will review key IBEX and Voyager observations that inform us of the VLISM environment, in particular the local interstellar magnetic field, which is important for understanding the galactic cosmic ray fluxes observed at Earth. Speaker: Eric Zirnstein (Princeton University) • 3:00 PM Completing and Improving the TeV Cosmic-ray Sky with HAWC 15m In 2015, the HAWC Observatory was completed and began operation as the most sensitive TeV cosmic-ray detector in the Northern Hemisphere. Since that time, we have recorded over 1 trillion cosmic-ray air showers, designed a likelihood-based cosmic-ray energy reconstruction, and implemented a new minimally-biased method for reconstructing all-sky anisotropy. These three advances in statistics, energy resolution, and signal recovery allow us to better disentangle the properties of the TeV cosmic-ray anisotropy from detector effects. This has led to a combined anisotropy sky map with IceCube in the Southern Hemisphere. Although the nature of this anisotropy has been explored and modeled, the exact realization of the anisotropy could hold clues important to describing local accelerators of observed cosmic rays and the local magnetic fields through which they propagate. We will share our results for both HAWC and the combined HAWC-IceCube anisotropy sky maps. Speaker: Dr Daniel Fiorino (University of Maryland College Park) • 3:15 PM A search for cosmic-ray proton anisotropy with the Fermi Large Area Telescope 15m Although cosmic rays are nearly isotropic, ground-based arrays sensitive to TeV cosmic rays have measured a small anisotropy in right ascension. Understanding the morphology and energy dependence of this anisotropy can yield insight into cosmic-ray sources and propagation in the local magnetic field. The Fermi Large Area Telescope (LAT) is optimized for gamma-ray measurements, but it records cosmic-ray protons at an even higher rate. We present a Fermi LAT search for cosmic-ray proton anisotropy at energies ~100 GeV and greater. The energy range is complementary to ground-based measurements. Moreover, while ground-based instruments cover only part of the sky and most are only sensitive to the right ascension component of the anisotropy, the LAT is sensitive to the full sky and to all orientations of anisotropy. Speaker: Prof. Justin Vandenbroucke (University of Wisconsin) • 2:00 PM 3:30 PM Cosmology Spartan Room (The Athenaeum) ### Spartan Room #### The Athenaeum Convener: Tom Giblin (Kenyon College) • 2:00 PM Blazar Halo Morphology as a Probe of Helical Intergalactic Magnetic Fields 15m In models of early universe cosmology, primordial magnetic fields with helicity can be created during cosmological inflation, and they may play a role in the generation of the matter / antimatter asymmetry of the universe. Such a primordial magnetic field will persist in the universe today as an intergalactic magnetic field, and the discovery of this cosmological relic will open a new window onto the early universe. In this talk I will discuss a new probe of helical intergalactic magnetic fields through TeV blazar halo morphology. The emission of TeV gamma rays from blazars at cosmological distances will induce an electromagnetic cascade when the TeV gamma rays are incident upon starlight and produce electron-positron pairs. These charged leptons are deflected by the presence of an intergalactic magnetic field, which forms a halo of GeV cascade gamma rays around the blazar. In this talk I will discuss how the halo can acquire a parity-violating shape if the intergalactic magnetic field is helical. Speaker: Andrew Long (University of Chicago) • 2:15 PM Weak lensing science with the WFIRST high-latitude survey 15m Hyper Suprime-Cam (HSC) is an imaging camera mounted at the Prime Focus of the Subaru 8.2-m telescope operated by the National Astronomical Observatory of Japan on the summit of Maunakea in Hawaii. A consortium of astronomers from Japan, Taiwan and Princeton University is carrying out a three-layer, 300-night, multiband survey from 2014-2019 with this instrument. In this talk, I will focus on the HSC survey Wide Layer, which will cover 1400 square degrees in five broad bands (grizy), to a 5 sigma point-source depth of r~26. We have covered 240 square degrees of the Wide Layer in all five bands, and the median seeing in the i band is 0.60 arcseconds. This powerful combination of depth and image quality makes the HSC survey unique compared to other ongoing imaging surveys. In this talk I will describe the HSC survey dataset and the completed and ongoing science analyses with the survey Wide layer, including galaxy studies, strong and weak gravitational lensing, but with an emphasis on weak lensing. I will demonstrate the level of systematics control, the potential for competitive cosmology constraints, some early results, and describe some lessons learned that will be of use for other ongoing and future lensing surveys. Speaker: Rachel Mandelbaum (Carnegie Mellon University) • 2:30 PM Probing Dark Energy with the Canadian Hydrogen Intensity Mapping Experiment (CHIME) 15m CHIME will use the 21cm emission line of neutral hydrogen to map large-scale structure between redshifts of 0.8 and 2.5. By measuring Baryon Acoustic Oscillations (BAO) we will place constraints on the dark energy equation of state as it begins to dominate the expansion of the Universe, particularly at redshifts poorly probed by current BAO surveys. In this talk I will introduce CHIME, a transit radio interferometer designed specifically for this purpose. I will discuss its goals and describe the powerful new analysis techniques we have developed to confront the many challenges of such observations, in particular removal of astrophysical foregrounds which are six orders of magnitude larger than the 21cm signal. A smaller 40m x 37m pathfinder telescope is currently operating at the DRAO in Penticton, BC, and the full-sized 80m x 100m instrument will be completed this year. I will report on current progress, and the lessons already learned. Speaker: Dr Richard Shaw (University of British Columbia) • 2:45 PM Cosmological Tests with Type Ia Supernovae 15m Type Ia supernovae (SNe Ia) provided the first direct evidence for the accelerated expansion of the universe, leading to the now-standard Lambda-CDM model featuring dark energy. Beyond direct dark energy measurements, these accurate standard candles can be employed in a variety of ways to test the Lambda-CDM model. I will show how an analysis of the peculiar velocities of SNe Ia constitutes a powerful test of the cosmological model at the lowest redshifts. I will also illustrate that, while SNe Ia fundamentally measure distance, careful treatment can yield unbiased measurements of the relative expansion rate, facilitating fast subsequent cosmological inference and complementarity with similar measurements from other probes of geometry. I will present the highest-redshift SN Ia measurement of expansion from SNe observed via the HST CANDELS & CLASH programs. Speaker: Dr Daniel Shafer (Johns Hopkins University) • 3:00 PM Sample variance in the local measurements of the Hubble constant 30m The Hubble constant H0 — the expansion rate of the Universe today — has recently been measured to percent-level precision, but two of the key results are in tension. The local measurements using distance ladders have indicated H0 ~ 73 km/s/Mpc, while the global measurements using cosmic microwave background have indicated H0 ~ 67 km/s/Mpc. In this talk, I will first review the methods and results of both local and global measurements. I will then present our efforts of using simulations to quantify the sample variance in the local measurements of H0. Taking into account the inhomogeneous selection of type Ia supernovae, we find that this tension cannot be alleviated by sample variance or local density fluctuations. I will conclude with other possible causes of this tension. Speaker: Hao-Yi Wu • 2:00 PM 3:30 PM Dark matter Small Theater (The Athenaeum) ### Small Theater #### The Athenaeum Convener: Francesca Calore (LAPTh, CNRS) • 2:00 PM Empirical Determination of Dark Matter Velocity Distribution Using Metal Poor Stars 15m In this talk, I will show that metal poor halo stars have similar kinematics as dark matter in the solar neighborhood, using the hydrodynamic zoom-in simulation Eris of the Milky Way. Within this expectation, I extract the first empirically-determined dark matter velocity distribution using the velocity dispersions of the halo stars as measured by the Sloan Digital Sky Survey, and show that using this newly-found velocity distribution, the direct detection limits on dark matter scattering off nuclei are loosened by almost an order of magnitude at low dark matter masses. Speaker: Lina Necib (MIT) • 2:15 PM On the applicability of Eddington's inversion methods to direct dark matter searches 15m Predictions for direct dark matter searches rely on the knowledge of the local speed distribution of dark matter particles. This distribution can be derived within a dynamically constrained Milky Way mass model using the Eddington formalism or some extended versions of it. This method, however, can lead to unconsistent or unphysical solutions, depending on the details of the mass model. I will discuss the limitations of the method and its applicability to predictions in direct detection. I will also discuss how it may, or may not, capture the actual dynamics of dark matter by comparing with cosmological simulation results. Speaker: Martin Stref (Montpellier University) • 2:30 PM Astrophysical distribution of dark matter and direct detection implications 15m The interpretation of dark matter direct detection results is complicated due to the unknown distribution of dark matter in our local neighborhood. Astrophysical uncertainties in the dark matter distribution are a major barrier preventing a precise determination of the properties of the dark matter particle. High resolution cosmological simulations of galaxy formation including baryons have recently become possible, and provide important information on the properties of the dark matter halo. I will discuss the local dark matter density and velocity distribution of Milky Way-like galaxies obtained from recent hydrodynamical simulations. In particular I will discuss the effect of baryons on the dark matter velocity distribution, the prevalence of dark disks, and implications for dark matter direct detection. Speaker: Nassim Bozorgnia (GRAPPA, University of Amsterdam) • 2:45 PM Reverse Direct Detection: Cosmic Ray Tests of Light Dark Matter Elastic Scattering 15m Many dark matter studies have considered indirect detection (χχ → ff), direct detection (χf →χf ), and collider searches (ff → χχ). We propose a new strategy in searching for dark matter elastic cross section by considering cosmic-ray propagation in the galactic dark matter halo. We ﬁnd that cosmic rays can lose signiﬁcant fraction of their energy through scattering with dark matter (fχ → fχ). Using existing cosmic-ray data and a simple cosmic-ray propagation model, we study the qualitative eﬀects of dark matter scattering on cosmic-ray propagation and obtain new constraints of dark matter elastic cross sections on light dark matter (keV–GeV), a regime that is diﬃcult for traditional direct detection experiments to probe. Speaker: Mr Christopher Cappiello (The Ohio State University) • 3:00 PM Determinations of Properties of Low-Mass WIMPs from Direct Dark Matter Detection Experiments with Non-negligible Threshold Energy 15m In this talk, we discuss the effects of a non-negligible threshold energy on our model-independent methods developed for reconstructing WIMP properties by using measured recoil energies in direct Dark Matter detection experiments directly. Our expressions for reconstructing the mass and the (ratios between the) spin-independent and the spin-dependent WIMP-nucleon couplings have been modified. We will focus on low-mass (m_chi <~ 50 GeV) WIMPs and present some (preliminary) numerical results obtained by Monte-Carlo simulations. Speaker: Dr Chung-Lin SHAN (Xinjiang Astronomical Observatory, Chinese Academy of Sciences) • 3:15 PM Hunting for WIMPs, how low should we go? 15m We discuss direct detection of WIMP dark matter in two benchmark cases: a Majorana fermion that primarily interacts via the Z-boson, and a Majorana fermion whose relic density is primarily set via co-annihilations with colored partners. We discuss the Z-mediated case with reference to a simple UV-completion, the singlet doublet model. We discuss the co-annihilation case with reference to stop co-annihilation in the Minimal Supersymmetric Standard Model. We find that Z-mediated Dark Matter is likely to be largely probed by future experiments, but co-annihilating Dark matter may present a formidable challenge. Speaker: Aaron Pierce (University of Michigan) • 2:00 PM 3:30 PM Gamma rays Corinthian Room (The Athenaeum) ### Corinthian Room #### The Athenaeum Convener: Hugo Ayala (Pennsylvania State University) • 2:00 PM Cherenkov Telescope Array: The Next Generation Gamma-ray Observatory 15m The Cherenkov Telescope Array (CTA) will be a new observatory to study very-high-energy gamma-ray sources. It is designed to achieve an order of magnitude improvement in sensitivity in the 20 GeV to 300 TeV energy band compared to currently operating instruments: VERITAS, MAGIC, and H.E.S.S. CTA will probe known sources with unprecedented sensitivity, angular resolution, and spectral coverage, while also detecting hundreds of new sources. This presentation describes the science drivers for CTA and the status of the project with an emphasis on the planned US contribution. Speaker: A. Nepomuk Otte • 2:15 PM Overview and current status of the ALPACA experiment 15m The ALPACA (Andes Large area PArticle detector for Cosmic ray physics and Astronomy) experiment is aimed at observing cosmic gamma rays above 10 TeV in the southern sky with wide field of view and high sensitivity. We will construct an 83,000 m^2 surface air-shower array and a 5,400 m^2 underground muon detector array, on a highland (Chacaltaya Hill) at the altitude of 4,740 m halfway up Mt. Chacaltaya on the outskirts of La Paz, Bolivia. Prior to the construction of the full ALPACA array, we are planning to build a 1/10-scale prototype air-shower array. In this talk, the overview and current status of the ALPACA experiment will be reported. Speaker: Dr Takashi SAKO (Yachay Tech University) • 2:30 PM All-Sky Medium Energy Gamma-ray Observatory (AMEGO) - A discovery mission for the MeV gamma-ray band 15m The MeV domain is one of the most underexplored windows on the Universe. From astrophysical jets and extreme physics of compact objects to a large population of unidentified objects, fundamental astrophysics questions can be addressed by a mission that opens a window into the MeV range. AMEGO is a wide-field gamma-ray telescope with sensitivity from ~200 keV to >10 GeV. AMEGO provides three new capabilities in MeV astrophysics: sensitive continuum spectral studies, polarization measurements, and nuclear line spectroscopy. AMEGO will consist of four hardware subsystems: a double-sided silicon strip tracker with analog readout, a segmented CZT calorimeter, a segmented CsI calorimeter and a plastic scintillator anticoincidence detector, and will operate primarily in an all-sky survey mode. In this presentation we will describe the AMEGO mission concept and scientific performance. Speaker: Dr Jeremy Perkins (NASA/GSFC) • 2:45 PM Ex Luna Scienta: The Lunar Occultation Explorer (LOX) 15m The Lunar Occultation Explorer (LOX) is a paradigm shift - a next-generation mission concept that will provide new capabilities in time-domain nuclear astrophysics and establish the Moon as a platform for nuclear astrophysics. Currently under review by NASA’s Explorer Program, LOX's performance requirements are driven by focused science goals designed to resolve the enigma of Type-Ia supernova (SNeIa) and their role in galactic evolution and cosmology. LOX will survey and continuously monitor the Cosmos in the MeV regime (0.1-10 MeV), a unique capability that supports both the primary science goals as well as multi-messenger detection and monitoring campaigns, by leveraging the Lunar Occultation Technique (LOT). Key benefits of the LOX/LOT approach include maximizing the ratio of sensitive-to-total deployed mass, low implementation risk, and demonstrated operational simplicity that leverages extensive experience with planetary orbital geochemistry investigations. LOX will also deliver a time-domain survey of the nuclear cosmos. Proof-of-principle efforts have validated all aspects of the mission using previously deployed lunar science assets, including the first high-energy gamma-ray source detected at the Moon. LOX mission design, performance, and science will be presented. Speaker: Prof. Richard Miller (University of Alabama in Huntsville) • 3:00 PM Fermi's view of the gamma-ray sky above 10 GeV 15m We present some of the main results from the Third Catalog of Hard Fermi-LAT Sources (3FHL). This catalog, based on the first 7 years of LAT data using the Pass 8 event-level analysis, contains 1556 sources characterized in the 10 GeV--2 TeV energy range. The sensitivity and angular resolution are improved by factors of 3 and 2 relative to the previous LAT catalog in this energy range (1FHL). Most 3FHL sources (79%) are extragalactic, while 9% are Galactic and 12% are unassociated (or associated with a source of unknown nature). The catalog includes 214 new gamma-ray sources. The 3FHL catalog provides an excellent opportunity to relate observations from space to those accessible from the ground (e.g. HESS, MAGIC, VERITAS, HAWC), including in the near future with the Cherenkov Telescope Array. Speaker: Dr Pablo Saz Parkinson (The University of Hong Kong) • 3:15 PM Free 15m Free • 2:00 PM 3:30 PM Neutrinos Athenian Room (The Athenaeum) ### Athenian Room #### The Athenaeum Convener: Sergio Palomares-Ruiz (IFIC-Valencia) • 2:00 PM High-energy neutrino interactions: first cross section measurements at TeV and above 15m Neutrino interactions, though feeble, are tremendously important in particle physics and astrophysics. Still, at neutrino energies above ~350 GeV there has been, up to now, no direct experimental information on neutrino interactions; calculations rely on extrapolations from lower energies. Now, for the first time, we can measure the neutrino-nucleon cross section at the TeV scale and above, thanks to the recent discovery, by IceCube, of high-energy astrophysical neutrinos. We will show new cross section measurements extracted from the 4-year sample of IceCube High Energy Starting Event showers between 20 TeV and 2 PeV. The measurements agree with standard cross-section calculations and constrain new physics beyond the Standard Model at these energies. Speaker: Mauricio Bustamante (Ohio State University) • 2:15 PM New physics searches with the TeV scale neutrinos 15m IceCube observation of high-energy astrophysical neutrinos has opened the astrophysical neutrino window. As we accumulate statistics IceCube not only starts characterizing the astrophysical neutrino component, but also makes improved measurements of the highest energy atmospheric neutrinos. In this talk I will discuss how we can use both high-energy atmospheric neutrinos as well as astrophysical neutrinos as a probe of new physics. Speaker: Carlos Arguelles (MIT) • 2:30 PM Imaging Galactic Dark Matter with IceCube High-Energy Cosmic Neutrinos 15m The origin of the observed extraterrestrial neutrinos is still unknown, and their arrival directions are compatible with an isotropic distribution. This observation, together with dedicated studies of Galactic plane correlations, suggest a predominantly extragalactic origin. Dark matter-neutrino interactions, which have been extensively studied in cosmology, would thus lead to a slight suppression of flux at energies below a PeV and deficit of events in the direction of Galactic center, which would be seen by IceCube. I will present results of a recent analysis using the four-year high-energy starting event dataset to constrain the strength of dark matter-neutrino interactions and show that in spite of low statistics IceCube can probe regions of the parameter space inaccessible to current cosmological methods. Speaker: Ali Kheirandish • 2:45 PM Searching for Planck Scale Physics with High Energy Neutrinos 15m Some Planck-scale physics and quantum gravity models predict a slight violation of Lorentz invariance (LIV) at high energies. High-energy cosmic neutrino observations can be used to test for such LIV. Operators in an effective field theory (EFT) can be used to describe the effects of LIV. They can be used to describe kinematically allowed energy losses of possible superluminal neutrinos. These losses can be caused by both vacuum pair emission (VPE) and neutrino splitting. Assuming a reasonable distribution of extragalactic neutrino sources, we determined the resulting after-loss neutrino spectra using Monte Carlo propagation calculations. We then compared them with the neutrino spectrum observed by IceCube to determine the implications of our results regarding Planck-scale physics. If the drop off in the observed IceCube neutrino flux above 2 PeV is caused by LIV, a potentially significant pileup effect would be produced just below the drop-off energy in the case of CPT-even operator dominance. However, such a clear drop off effect would not be observed if a CPT-odd, CPT-violating term dominates. Speaker: Floyd Stecker (NASA/GSFC) • 3:00 PM Constraining the Flavor Structure of Lorentz Violation Hamiltonian with the Measurement of Astrophysical Neutrino Flavor Compositions 15m We study Lorentz violation effects to flavor transitions of high energy astrophysical neutrinos. It is shown that the appearance of Lorentz violating Hamiltonian can drastically change the flavor transition probabilities of astrophysical neutrinos. Predictions of Lorentz violation effects to flavor compositions of astrophysical neutrinos arriving on Earth are compared with IceCube flavor composition measurement which analyzes astrophysical neutrino events in the energy range between$25~{\rm TeV}$and$2.8~{\rm PeV}$. Such a comparison indicates that the future IceCube-Gen2 will be able to place stringent constraints on Lorentz violating Hamiltonian in the neutrino sector. We work out these expected constraints for different flavor structures of Lorentz violating Hamiltonian. In some cases these expected constraints can improve upon the current constraints obtained from other types of experiments by more than two orders of magnitudes. Speaker: Mr Wei-Hao Lai (National Chiao-Tung University) • 3:15 PM Hidden neutrino interactions with dark energy: Effects on oscillation probabilities and tests with high-energy neutrinos 15m If dark energy is some kind of scalar field rather than a cosmological constant and can interact with the neutrino sector, it might cause CPT/Lorentz violating effects and also modifies the neutrino oscillation phenomenology. The effects will be insignificantly small compared to the ordinary oscillation effect at low energies, but might become visible in very high energies, since the terms in the transition probability induced by interactions with dark energy do not depend on the energy, while the ordinary component decreases with 1/E. If such dark energy effects were found, it would be a strong indication that the nature of dark energy is different from a cosmological constant. We investigate the effect of such a dark energy interaction in the three-neutrino scheme and use IceCube data to put constraints on the new oscillation parameters that emerge from this interaction. Speaker: Ms Niki Klop (GRAPPA, University of Amsterdam) • 3:30 PM 4:00 PM Coffee break 30m Oak Room (The Athenaeum) ### Oak Room #### The Athenaeum • 4:00 PM 6:00 PM Dark matter Small Theater (The Athenaeum) ### Small Theater #### The Athenaeum Convener: Kerstin Perez (MIT) • 4:00 PM ABRACADABRA: A novel approach to detecting axion dark matter 15m ABRACADABRA is a proposed experiment to search for ultralight (10^-14 - 10^-6 eV) axion dark matter. When ultralight axion dark matter encounters a static magnetic field, it sources an effective electric current that follows the magnetic field lines and oscillates at the axion Compton frequency. In the presence of axion dark matter, a large toroidal magnet will act like an oscillating current ring, whose induced magnetic flux can be measured by an external pickup loop inductively coupled to a SQUID magnetometer. The readout circuit can be broadband or resonant and both are considered. ABRACADABRA is fielding a 10-cm prototype in 2017 with the intention of scaling to a 1m^3 experiment. The long term goal is to probe QCD axions near the GUT-scale. In this talk I will review the design, sources of noise, and sensitivity of the experiment. Speaker: Benjamin Safdi (massachusetts institute of technology) • 4:15 PM The Axion Dark Matter Experiment 15m The Axion Dark Matter Experiment, ADMX, is taking data with sensitivity to a possible dark matter candidate that would also solve the strong-CP problem of QCD. The experiment, it's status, and preliminary results will be presented along with a path to cover much of the highly motivated parameter space. Speaker: William Wester • 4:30 PM Axion and ALP Dark Matter Search with the International Axion Observatory (IAXO) and mini-IAXO 15m The nature of dark matter (DM) remains one of the fundamental questions in cosmology. Axions are one of the current leading candidates for the hypothetical, non-baryonic DM. Especially in the light of LHC slowly closing in on WIMP searches, axions and axion-like particles (ALPs) provide a viable alternative approach to solving the dark matter problem. The fact that makes them very appealing is that they were initially introduced to solve a long-standing QCD problem in the Standard Model of particle physics. Helioscopes are searching for axions produced in the core of the Sun via the Primakoff effect. The International Axion Observatory (IAXO) is a next generation axion helioscope aiming at a sensitivity to the axion-photon coupling of 1 - 1.5 orders of magnitude beyond the currently most sensitive axion helioscope (CAST). IAXO will be able to challenge the stringent bounds from SN1987A and test the axion interpretation of anomalous white-dwarf cooling. Beyond standard axions, this new experiment will be able to search for a large variety of ALPs and other novel excitations at the low-energy frontier of elementary particle physics. Mini-IAXO is proposed as a small pilot experiment increasing the sensitivity to axion-photon couplings down to a few 10$\times$11 GeV$^{-1}$. This contribution will introduce the IAXO and mini-IAXO experiments and outline the expected science reach. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. Speaker: Julia Katharina Vogel (Lawrence Livermore Nat. Laboratory (US)) • 4:45 PM The Axion Resonant InterAction Detection Experiment (ARIADNE) 15m The Axion Resonant InterAction Detection Experiment (ARIADNE) will search for evidence of the QCD axion using nuclear magnetic resonance to search for a short-range spin-dependent interaction in the sub-millimeter range, which results from the Axion. ARIADNE features spin polarized 3He interacting with a rotating unpolarized tungsten mass as a probe for this interaction. We will outline the concept of the measurement and describe the status of the R&D progress to date. Speaker: Justin Shortino • 5:00 PM A Fresh Look at Axions: Using NuSTAR Solar Observations in Search for Dark Matter 15m While the discovery of the Higgs boson at the LHC experimentally confirms the widely successful Standard Model (SM) of particle physics, the theory still falls short of explaining several fundamental features of our Universe. A major shortcoming is the SM’s silence on the nature of Dark Matter (DM). Currently, axions and WIMPs are the leading DM candidates with axions simultaneously addressing an additional weakness of the SM, i.e. its inability to explain why strong interactions do not violate charge-parity symmetry as expected from theory. Non-QCD axions on the other hand appear naturally in extensions of the SM, e.g. string theory. If axions exist, they will be created in great numbers in the solar core by the Primakoff effect, via the interaction of a photon from the core’s radiation field with a virtual photon in a nucleus. By the inverse mechanism, one can generate an X-ray flux beyond the solar core. Extensive ground-based searches, notably the CAST experiment at CERN and the proposed next generation helioscope IAXO, use laboratory magnets for the reverse conversion. We employ a novel approach using solar observations of NASA’s hard x-ray astrophysics mission NuSTAR (Nuclear Spectroscopic Telescope Array) to search for the same process via magnetic fields in the solar corona, which, although weaker than those of laboratory magnets, are much more extensive in scale. We will report on the latest results of our research. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. Speaker: Jaime Ruz Armendariz (Lawrence Livermore Nat. Laboratory (US)) • 5:15 PM Emission of Photons and Relativistic Axions from Axion Stars 15m The number of nonrelativistic axions can be changed by inelastic reactions that produce relativistic axions or photons. Any even number of nonrelativistic axions can scatter inelastically into two relativistic axions. Any odd number of axions can annihilate into two photons. This reaction produces a monochromatic radio-frequency signal at an odd-integer harmonic of the fundamental frequency set by the axion mass. The loss rates of axions from axion stars through these inelastic relations are calculated using the framework of a nonrelativistic effective field theory. Odd-integer harmonics of a fundamental radio-frequency signal provide a unique signature for collapsing axion stars or any dense configuration of axions. Speaker: Abhishek Mohapatra (The Ohio State University) • 5:30 PM Signatures of dark-matter sub-structure in axion direct detection experiments 15m ABRACADABRA10cm is a new experiment which seeks to detect axion dark matter through its interactions with the electromagnetic field. The experiment, which is planned to start collecting data this year, will probe unstudied regions of axion parameter space and lay the groundwork for future, larger-scale efforts. I will discuss the results of numerical and analytical work towards understanding the signatures of axion dark matter substructure in the experiment. In particular, I will focus on the effects of dark matter streams, especially as informed by cosmological N-body simulation data. Speaker: Joshua Foster (University of Michigan) • 5:45 PM Free 15m Free • 4:00 PM 6:00 PM Extragalactic sources Macedonian Room (The Athenaeum) ### Macedonian Room #### The Athenaeum Convener: Emma Storm (GRAPPA, University of Amsterdam) • 4:00 PM Symmetric Achromatic Variability: A New and Totally Unexpected Phenomenon 30m We have discovered a rare new form of long-term radio variability in the light-curves of active galaxies (AG) (arXiv:1702.06582, arXiv:1702.05519) --- Symmetric Achromatic Variability (SAV) --- a pair of opposed and strongly skewed peaks in the radio flux density observed over a broad frequency range. We propose that SAV arises through gravitational milli-lensing when relativistically moving features in AG jets move through gravitational lensing caustics created by 10^3-10^6 solar mass subhalo condensates or black holes located within intervening galaxies. The lower end of this mass range has been inaccessible with previous gravitational lensing techniques. This new interpretation of some AG variability can easily be tested and if it passes these tests, will enable a new and powerful probe of cosmological matter distribution on these intermediate mass scales, as well as provide, for the first time, micro-arcsecond resolution of the nuclei of AG --- a factor of 30--100 greater resolution than is possible with ground-based millimeter VLBI. Speaker: Dr Anthony Readhead (Caltech) • 4:30 PM F-GAMMA program: high-cadence, multi-wavelength radio monitoring as a probe of the physical conditions and variability processes in AGN jets 15m The jets of active galactic nuclei (AGN) are among the most powerful systems in the Universe. Their emission spans over an extremely wide energy range, from radio to gamma-rays or even TeV energies, and often shows pronounced variability with timescales anywhere between a few years and several minutes. Therefore, high-cadence, multi-band monitoring programs are essential in the investigation of their physical conditions and variability processes. The F-GAMMA (Fermi-GST AGN Multi-frequency Monitoring Alliance) was a program for the monitoring of the broad-band radio emission of about 90 Fermi-GST AGN, 25 of which have been detected also at TeV energies. The sources were observed from 2007 to 2015 at 12 radio frequencies between 2.6 GHz and 345 GHz with a mean cadence of 1-1.3 months. Both flux-density and (linear and circular) polarization variability was monitored. Here we present a compilation of science highlights from the F-GAMMA program, which include various multi-band correlation and population studies (e.g. gamma-ray loudness versus radio variability, radio versus gamma-ray fluxes, variability of FSRQs and BL Lacs), the localization of the gamma-ray emission site in AGN jets, the calculation of their Doppler factors using their multi-wavelength variability as well as a unification scheme for their broad-band spectral variability patterns which show an extremely diverse behavior. Speaker: Ioannis Myserlis (Max-Planck-Institut für Radioastronomie) • 4:45 PM Identifying Short, Extreme Blazar Flares with the HAWC Real-Time Flare Monitor 15m We present a search for hour-scale very high energy (VHE) flares from 187 blazars monitored by the HAWC observatory. With a wide field of view of ~2 sr and sensitivity to energies above a few hundred GeV, HAWC functions as a survey instrument and facilitates searches for rapid variability in the VHE band. The currently operational HAWC real-time flare monitor takes advantage of this capability by issuing alerts within minutes of the identification of flaring activity. In this presentation, we describe the real-time flare monitor and report on the detection of several rapid flares in over 2 years of data collected between November 2014 and February 2017. We interpret these observations as an unbiased constraint on the rate of extreme blazar flares. We also summarize the prospects for future multiwavelength studies of extreme flares detected by the real-time flare monitor to provide clues into the mechanisms powering the blazar jets and probe the particles and fields in intergalactic space. Speaker: Dr Thomas Weisgarber • 5:00 PM The AMEGO View of MeV AGNs 15m Extensive observations by Fermi, AGILE, and TeV telescopes have opened a new window into the high-energy physical processes of AGNs and raised questions about the physics of their jets, their formation and cosmological evolution, and their impact on their environments and the growth of structure in the Universe. Multiwavelength observations in X-rays and at GeV and TeV energies point to a large class of blazars whose peak output is in the poorly explored MeV band. With unprecedented sensitivity between 200 keV and 10 GeV, the All-Sky Medium Energy Gamma-ray Observatory (AMEGO) will fill in the MeV gap in blazar spectral energy distributions, providing crucial clues about their emission mechanisms in this regime. Also, with its wide field of view, AMEGO will survey the entire sky every 3 hours, allowing it to monitor variations in blazar light curves on short and long timescales that arise from changes in their jets. Furthermore, multiwavelength observations of the blazar population indicate that the sub-population of MeV blazars are among the most distant and luminous AGNs; thus, AMEGO observations of MeV blazars will allow it to probe the growth of supermassive black holes at earlier epochs than allowed by other types of AGNs. Speaker: Tonia Venters (NASA Goddard Space Flight Center) • 5:15 PM Multi-Wavelength Correlations and AGN as Possible Particle Accelerators 15m Robust connections exist between various energy regions in the spectra of nearby galaxies. The flux ratios from widely separated spectral regions are often remarkably constant while originating via very different processes with varying efficiencies. Although the radio-far infrared (FIR) correlation is best known, consistent flux ratio relationships also are found between gamma-rays and the FIR, as well as between gamma-ray and radio fluxes. These relationships are understood in cases where the underlying linkage involves related power sources, such as massive stars. However, some systems containing substantial AGNs as well as starbursts still fall close to the standard flux ratio correlations. In this talk, I will explore some of the astronomical issues playing into the interpretation of these correlations and also briefly touch on the range of cosmic power sources that may produce these patterns. T Speaker: John Gallagher • 5:30 PM Astrophysics with Novel Observables 15m Despite intensive research, some fundamental properties of the most luminous particle accelerators and transients like AGNs, GRBs, etc. are unknown. Location and mechanisms of particle acceleration, connection to flaring and quiescent states, leptonic vs hadronic emission are open questions. Complexity of environments and processes make it hard to disentangle different scenarios. This suggests complementing conventional observables like the broadband spectrum with novel statistical observables like power spectral density (PSD) and the flux probability distribution (PDF) extracted from lightcurves, high and low energy polarisation, etc. While the PSD encodes the temporal structure of dynamical processes, particle acceleration and radiation and observing cadence, the PDF encodes the fundamental form of the emission processes (additive vs multiplicative). Polarised emission provides independent constraints on region geometry, magnetic fields, scattering processes, etc. to those from the above observables. These observables and related methods are also relevant for population studies. For e.g., time series methods used to compute the PSD, can also be used to estimate transient detection probability and resultant changes in source flux distribution,$\frac{dN}{dF}\$. A detailed theoretical framework capable of predicting these statistical observables from first principles in these sources is currently in nascency. Finally, they are complementary and potentially crucial crosschecks to neutrino and gravitational wave observations
in the multi-messenger era. In this presentation, I demonstrate the
potential of using such novel observables and related methods to probe physics of individual particle accelerators and the population at large by applying it to prominent blazars like Mrk 421, BL Lac, PKS 2155, etc.

Speaker: Dr Nachiketa Chakraborty (Max-Planck-Institut fuer Kernphysik)
• 5:45 PM
The magnetic reconnection model for blazar emission 15m

The recent observations of powerful, minute-timescale TeV flares from
several blazars pose serious challenges to theoretical models for the
blazar emission. In this talk, I will discuss the magnetic
reconnection model for the blazar flaring. I argue that radiation
emitted from the reconnection layers can account for the observed
“envelope” of ~day-long blazar activity as well as the fastest
observed flares. Moreover, I will show that the reconnection model
predicts that the emission regions are characterized by rough
equipartition between radiating particles and magnetic fields;
in agreement with observations. Finally, I will show examples of lightcurves and spectra
calculated directly with first-principle Particle in cell simulations of the magnetic reconnection layer.

Speaker: Prof. Dimitrios Giannios (Purdue University)
• 4:00 PM 6:00 PM
Galactic sources Corinthian Room (The Athenaeum)

### Corinthian Room

#### The Athenaeum

Convener: Pablo Saz Parkinson (The University of Hong Kong)
• 4:00 PM
Galactic Sources with HAWC 30m

The High-Altitude Water Cherenkov (HAWC) TeV Gamma-Ray Observatory in Mexico is a wide-field-of-view telescope with a nearly 100 % duty cycle. It has been taking data with a complete detector configuration since spring 2015 and is particularly well suited to measure very energetic transient and extended gamma-ray emission in our Galaxy. In my presentation, I will give an overview of the most recent HAWC results relating to Galactic sources. This will include highlights from the 2HWC catalog, measurements of PWNe in the general Geminga region, and observations of binary systems and extended structures such as the Northern Fermi Bubble, molecular clouds, or diffuse emission at TeV energies.

Speaker: Petra Huentemeyer (Michigan Tech)
• 4:30 PM
VERITAS and Fermi-LAT observations of TeV gamma-ray sources from the second HAWC catalog 15m

The HAWC (High Altitude Water Cherenkov) observatory recently published their second source catalog with 39 very high energy gamma-ray sources based on 507 days of exposure time. We studied thirteen HAWC sources without known counterparts with VERITAS and Fermi-LAT data. VERITAS, an array of four imaging atmospheric Cherenkov telescopes observing gamma rays with energies higher than 85 GeV, can provide a more detailed image of the source with much shorter exposure time and with better angular resolution. With Fermi-LAT data, we searched for the counterparts at lower energies (E>10 GeV). VERITAS found weak gamma-ray emission in the region of PWN DA495 coinciding with 2HWC J1953+294 in this follow-up study. We will present results focusing on the PWN DA495 region and the SNR G54.1+0.3 region where Fermi-LAT detected a GeV counterpart of SNR G54.1+0.3, a known TeV source detected by both VERITAS and HAWC.

Speaker: Nahee Park (University of Chicago)
• 4:45 PM
Follow-up VERITAS and NuSTAR observations of Galactic HAWC gamma-ray sources 15m

The 2HWC gamma-ray catalog was recently released using 17 months of data from the HAWC observatory, a TeV surveying instrument located in Mexico. A total of 39 sources were detected, of which ~40% are not near known TeV sources and over half do not have clear association with known astrophysical sources. Many are extended and encompass multiple known X-ray and gamma-ray sources. In an effort to identify counterparts that could explain the complex morphology seen by HAWC and understand the emission mechanisms, follow-up observations by VERITAS in TeV have confirmed some detections. We obtained additional follow-up time for two Galactic HAWC sources in hard X-rays by NuSTAR. These are the initial observations of the HAWC-VERITAS-NuSTAR Galactic Survey Legacy program.

Speaker: Dr Michelle Hui (NASA/MSFC)
• 5:00 PM
A novel maximum likelihood method for VERITAS analysis 15m

Gamma ray astronomy provides a powerful way to study particle acceleration and diffusion within high-energy astrophysical phenomena such as supernova remnants and pulsar wind nebulae. Constructing a coherent physical picture of these sources requires the ability to detect extended regions of gamma-ray emission, the ability to analyze small-scale spatial variation within these regions, and the ability to synthesize data from multiple observatories across multiple wavebands. Air Cherenkov telescopes provide fine angular resolution (<1 degree), but their limited fields of view typically make detection of extended sources challenging.
Maximum likelihood methods are well-suited to simultaneous analysis of multiple fields with overlapping sources, and to combining data from multiple gamma-ray observatories. These methods allow for estimation of the cosmic ray background for air Cherenkov observations for sources as large as the entire telescope field of view. We report here on the development of a maximum likelihood approach for the air Cherenkov observatory VERITAS and discuss potential applications of this method.

Speaker: Tom Brantseg (Iowa State University)
• 5:15 PM
Observation of the Cygnus Region using HAWC data 15m

The Cygnus region consists of multiple gamma-ray source types such as pulsar wind nebulae (PWN), supernova remnants, binary systems, and star clusters. Several gamma-ray instruments have observed gamma-ray sources in this region. For instance, Fermi-LAT found gamma-ray emission at GeV energies due to a Cocoon of freshly accelerated cosmic rays, which is co-located with a known PWN seen by several TeV gamma-ray observatories. TeV J2032+4130 is likely powered by the pulsar PSR J2032+4127 based on the multi-wavelength observation and asymmetric morphology reported by VERITAS. The High Altitude Water Cherenkov (HAWC) observatory has reported five sources within the Cygnus region, three of which lie in the vicinity of the cocoon region reported by Fermi-LAT. This presentation will discuss the analysis of data collected with the HAWC instrument to provide a deeper understanding of the Cygnus cocoon. The study of HAWC data will provide more information regarding the morphology, emission origin, and the correlation with the GeV emission.

Speaker: Binita Hona (Michigan Technological University (for the HAWC collaboration))
• 5:30 PM