TeV Particle Astrophysics 2013

26 Aug 2013, 08:00 → 29 Aug 2013, 19:30 US/Pacific

Beckman Center of the National Academies of Sciences and Engineering

Kevork Abazajian (University of California, Irvine), Manoj Kaplinghat (University of California Irvine), Shunsaku Horiuchi (University of California, Irvine), Simona Murgia (University of California, Irvine), Steve Barwick (University of California, Irvine), Tim Tait (University of California, Irvine)

TeV Particle Astrophysics (TeVPA) is an annual international meeting in particle astrophysics. The UC Irvine particle physics and astrophysics groups will host TeVPA in 2013 at Irvine, California. This meeting will focus on topical issues in sources and propagation of cosmic rays and high-energy gamma rays, multi-wavelength probes of high-energy astrophysics, high-energy neutrino physics and searches for dark matter.

Monday, 26 August

07:00 → 08:30 Breakfast

08:30 → 10:30 Plenary

08:30 Results from IceCube

IceCube has been taken more than 3 years of data in its almost-full (79 strings)and full 86 string configuration. This talk will discuss recent results from the IceCube neutrino observatory with focus on a data set that shows first evidence for a population of very high energy neutrinos (100+ TeV) that cannot easily be explained by atmospheric neutrino background and may represent the first evidence for a population of high-energy neutrinos of extraterrestrial origin. These findings are based on an event sample with well contained vertices and additional suppression of downgoing atmospheric neutrino background. The results will be discussed and compared to the current status of analyses based on through-going muons and other contained event searches.

Speaker: Albrecht Karle (University of Wisconsin-Madison)

Slides IceCube_Karle_TeVPA2013.pdf

09:00 Latest news on ANTARES and KM3NeT Observatories

The ANTARES detector, located 40 km off the French coast, is the largest deep-sea neutrino telescope in the Northern Hemisphere with an instrumented volume of more than 0.01 cubic kilometers. The KM3NeT telescope has been designed to be the next generation of deep-sea telescope with an instrumented volume several hundred times larger. Both of them consist of an array of optical modules detecting the Cherenkov light induced by charged leptons produced by neutrino interactions in and around the detector. The first optical detector of KM3NeT has been deployed very recently on the ANTARES instrumentation line and the first muons observed. The primary goal of such telescopes is to search for astrophysical neutrinos in the TeV-PeV range. This comprises generic searches for any diffuse cosmic neutrino flux as well as more specific searches for astrophysical sources such as active galactic nuclei or Galactic sources. The search program also includes multi-messenger analyses based on time and/or space coincidences with other cosmic probes.

Speaker: Alexandre Creusot (APC, France)

Slides Creusot_ANTARES-KM3NeT-v2.pdf

09:30 Radio detection of cosmic rays with LOFAR

LOFAR is a multipurpose radio telescope which can be used for radio detection of cosmic rays while running astronomical observations at the same time. The core of LOFAR contains 2300 antennas within an area of four square kilometer. This high density makes it an ideal location for a detailed study of the radio signal of extensive air showers in the energy range 10$^{16}$ - 10$^{18}$ eV. We present the first analyses of high quality LOFAR events for which the lateral distribution of the radio signal can be studied in 2D. For each event dedicated simulation sets for proton and iron primaries have been produced. The radio and particle data are fitted simultaneously to the simulation. The data shows excellent agreement with simulation, indicating that the complicated emission mechanism is now well-understood. Moreover, the depth of the shower maximum (Xmax) can be inferred with an accuracy that is comparable to the fluorescence detection technique.

Speaker: Stijn Buitink

Slides buitink_tevpa.pdf

10:00 The interplay of cosmic rays and gamma rays

Speaker: Daniel Castro (MIT)

Slides castro.pdf

10:30 → 11:00 Coffee Break

11:00 → 12:30 Plenary

11:00 Probing the Very High Energy Universe with the Cherenkov Telescope Array

Speaker: David Williams (UCSC)

Slides Williams_TeVPA_CTA_daw.pdf

11:30 A Non-Thermal View of the Galactic Center

Speaker: Roland Crocker (Monash University)

Slides Crocker_GC_TeVPA_2013.pdf

12:00 Observations of Fermi bubbles and Evidence for Past Activities in the Galactic Center

Data from the Fermi-LAT revealed two large gamma-ray bubbles, extending 50 degrees above and below the Galactic center, with a width of about 40 degrees in longitude. I will show multi-wavelength studies of this so-called Fermi bubble structure including radio, microwave, and X-ray. Furthermore, we recently found evidence for large-scale collimated jet-like structure from Fermi-LAT data, penetrating through the bubbles from the Galactic center. This new piece of evidence provides further support of past activities in the Galactic center.

Speaker: Meng Su (MIT)

Slides Meng_Su_TeVPA_Plenary_talk_2013.pdf

12:30 → 14:00 Lunch break

14:00 → 16:00 High-energy neutrino

Conveners: Elisa Resconi (Technische Universität München), Kara Hoffman (University of Maryland)

14:00 Searches for Point and Extended Sources of Neutrinos with the IceCube Detector

Observing a neutrino point source would be a “smoking gun” signature of a cosmic ray accelerator. Here we present searches for time-independent neutrino emission from astrophysical sources using the IceCube detector. The analyses use data collected during the first four years of detector operation. An unbinned maximum likelihood method is used to search for individual point sources, spatially extended sources, and emission from specific source classes. These analyses are sensitive to TeV–PeV energy neutrinos in the northern sky and PeV–EeV neutrinos in the southern sky. Limits on extraterrestrial neutrino fluxes are compared to model predictions. Additionally, we show results from a search for point sources using a low-background sample of high-energy candidate neutrino events, and discuss upcoming improvements to IceCube point source searches.

Speaker: Jake Feintzeig

Slides Feintzeig_TeVPA_Aug13.pdf

14:24 Search for Neutrinos form Gamma-Ray Bursts with ANTARES

ANTARES is the largest high-energy neutrino telescope on the Northern Hemisphere. Its main scientific purpose is the search for astrophysical muon neutrinos that are detected via their charged-current interaction in Earth and the subsequent Cherenkov emission of the secondary muon in the water of the Mediterranean Sea. Among the most promising candidates are gamma-ray bursts, as they are thought to accelerate not only electrons -- leading to the observed gamma rays -- but also protons, which would yield the emission of EeV neutrinos. Additionally, their short duration provides intrinsically low coincident background. A search for muon neutrinos from gamma-ray bursts using data of the ANTARES telescope is presented here. Employing an extended maximum likelihood ratio search, the analysis is optimized for a discovery of a neutrino signal as predicted by the numerical NeuCosmA model. No significant excess over background is found, thus 90% confident level upper limits on the neutrino flux from the analytically approximated Guetta model and from the numerical NeuCosmA model are derived.

Speaker: Julia Schmid

Slides Schmid_TeVPA.pdf

14:48 Search for Prompt Neutrino Emission from Gamma Ray Bursts with IceCube

IceCube is the first neutrino telescope with TeV-PeV sensitivity sufficient to constrain the prompt neutrino flux from Gamma Ray Bursts (GRBs). Limits based on data from the 40- and 59-string partially completed detector configurations have been published previously. Much of the parameter space for the previous generation of neutrino fluence models was excluded, which has encouraged continued theoretical work on more precise GRB fireball particle physics calculations. With data from the first year of the completed 86-string detector, plus one year of the 79-string partial detector, our analysis is now more sensitive to prompt neutrino emission from GRBs by more than a factor of 2. We present results from analysis of the latest data set as well as combined results including data from the 40- and 59-string partial detector configurations.

Speaker: Mike Richman

Slides Richman_IceCube_NorthernGRBs_TeVPA2013.pdf

15:12 Search for correlation of high-energy starting events in IceCube with GRBs

IceCube is a cubic kilometer detector operating at the geographical South Pole. IceCube is sensitive to very-high-energy neutrinos. IceCube has reported evidence for the observation of astrophysical neutrinos in a set of 28 events collected between May 2010 and May 2012 with energies ranging from ~30 TeV to ~1.2 PeV. We present here the current status of a study of the temporal and spatial correlation of these 28 events with GRBs reported by satellites in the same time period. Compared to other GRB-neutrino correlation studies performed by IceCube, the present one is unique, as it used events actually suspected of being extraterrestrial, it is sensitive over 4$\pi$ sr and it is sensitive to all neutrino flavors. The very low background for this study allows us to test correlations from $\pm$10~s to $\pm$15~days around the GRB time.

Speaker: Ignacio Taboada

Slides Taboada_Neutrinos_TeVPA.pdf

15:36 Neutrino-Induced Cascades with IceCube

Speaker: Joanna Kiryluk

Slides kiryluk_TeVPA2013.pdf

14:00 → 16:00 Multi-wavelength studies of Galactic sources

Conveners: Greg Dobler (UCSB), Meng Su (MIT), Tesla Jeltema (UCSC)

14:00 VERITAS Galactic Physics

The VERITAS array of four imaging atmospheric Cherenkov telescopes, located at the Fred Lawrence Whipple observatory in southern Arizona, has been in full operation since September 2007. Sensitive in the ~80 GeV to 30 TeV regime, VERITAS has recently (Summer 2012) completed a full array upgrade including the installation of new high quantum efficiency photomultiplier cameras. VERITAS has performed deep observations on a variety of Galactic targets, yielding the detection of TeV emission from sources such as pulsar wind nebulae (PWNe), supernova remnants (SNRs), gamma-ray binaries, and more recently the >100 GeV emission from the Crab pulsar. We present some of the observational highlights from the VERITAS Galactic science program with an emphasis on those aspects that relate to the particle acceleration and the origin of cosmic rays in our Galaxy.

Speaker: Farzaneh Sheidaei

Slides Sheidaei_TeV2013_2_talk.pdf

14:24 The TeV Gamma-ray Milky Way as seen by H.E.S.S.

H.E.S.S. is an imaging Cherenkov telescope array in Namibia that has been observing the TeV sky during the last decade and has accumulated 3000 hours of high-quality data in a Galactic plane survey covering the region l = 250 to 65 deg in longitude and |b| < 3.5 deg in latitude. A population of over 60 sources was discovered with pulsar wind nebulae and supernova remnants being the largest identified source classes, while about a third of the sources remain without clear identification. In this talk I will present an overview of the H.E.S.S. Galactic plane survey with a focus on the methods, challenges and first results for a source catalog and population studies that are in preparation as well as a detailed view on the sources and diffuse emission in the Galactic centre region.

Speaker: Christoph Deil

Slides Deil_2013-08-26_TeVPA_HESS_Survey_Deil.pdf

14:48 TeV and GeV emitting supernova remnants: radio observations

TeV and GeV gamma-ray emissions from supernova remnants have been recently discovered using high energy instruments, including Cerenkov air shower experiments such as H.E.S.S. and Veritas, and space missions, primarily Fermi. The origin of the GeV and TeV emission in most SNRs is not known yet- it could be high energy electrons or high energy protons. In either case, TeV and GeV supernova remnants show great promise to increase our understanding of cosmic rays. We study TeV and GeV emitting SNRs utilizing recent neutral hydrogen (HI) 21 cm line surveys of the Galactic plane. For example, HI absorption spectra allow kinematic distances to be determined. Additionally, we use Galactic plane surveys in the CO line to measure molecular clouds, their kinematic distances and their relation to the TeV/GeV SNRs.

Speaker: Denis Leahy

Slides Leahy_TeVAstro.pdf

15:12 Dark matter Bremsstrahlung gamma ray signatures

We quantify the importance of the bremsstrahlung emission on the interstellar gas in computing indirect signatures of Dark Matter annihilation in the Galaxy, showing that it is the dominant component of the gamma-ray spectrum for some cases. We also find that, in regions in which bremsstrahlung dominates energy losses, the related γ-ray emission is only moderately sensitive to possible large variations in the gas density. Still, we stress that, for computing precise spectra in the (sub-)GeV range, it is important to compute self-consistently the gamma emission and the solution to the diffusion-loss equation as well as to obtain a reliable description of the inner Galaxy gas distribution. For example, these are crucial issues to quantify and interpret meaningfully γ-ray map ‘residuals’ in terms of (light) DM annihilations.

Speaker: Gabrijela Zaharijas

Slides Zaharijas_bremss.pdf

15:36 Pulsar-wind Nebulae as a Dominant Population of Galactic VHE Sources

During the past decade TeV gamma-ray observatories have revealed a large number of very-high energy (VHE) sources. We will review the TeV and X-ray properties of the population of Galactic VHE sources focusing on pulsar wind-nebulae associations and unidentified TeV sources. Pulsar-wind nebulae (PWNe), shell-type supernova remnants (SNRs), and microquasar-type high-mass X-ray binaries (HMXBs) appear to be firmly established sources of the leptonic cosmic rays in our Galaxy. They account for 48% of the total number (~90) of Galactic VHE sources, with 28 PWNe, 10 SNRs and 5 HMXBs. There is also a large number of extended TeV sources positionally coincident with young energetic pulsars; in most cases they can be considered as TeV PWN candidates. In addition, there remains a sizable fraction of unidentified VHE sources (~20). For some of these sources, multi-wavelength observations suggest a possible counterpart (such as an SNR interacting with a molecular cloud, or a star-forming region), but most of these associations are still uncertain because at least some of these sources still could be powered by offset pulsars whose PWNe are too faint in X-rays. Finally, there are "dark" VHE sources, for which neither radio nor X-ray images reveal any plausible counterparts. This work was partially supported by NASA grants NNX09AC84G and NNX09AC81G.

Speaker: Blagoy Rangelov

Slides Rangelov_Monday.pdf

16:00 → 16:30 Coffee Break

16:30 → 18:30 High-energy cosmic rays and their propagation

Conveners: Igor Moskalenko (Stanford), Mirko Boezio (INFN Trieste), Rene Ong (UCLA)

16:30 Cosmic Rays in the Heliosphere

The heliosphere is populated by a number of different species of energetic particles – galactic cosmic rays, anomalous cosmic rays, solar energetic particles and energetic particles accelerated in the interplanetary medium. The opportunity to study the transport and acceleration of these particles in great detail and, in many cases in situ, from spacecraft enables detailed comparison of theories and observations. Much of this is very relevant to TeV particle astrophysics, as the fundamental processes involved in acceleration and transport are in many cases the same. I will discuss the most-recent issues and insights prompted by observations from heliospheric spacecraft. Over the past several years, it was found that observations from the Voyager spacecraft in the outer heliosphere were quite different from expectation based on theory and modeling. These have led to much debate concerning the mechanism of transport and acceleration of energetic charged particles. In particular, whether charged-particle acceleration by shocks could account for the particles accelerated in the solar wind and its interaction with the interstellar medium. It has been suggested that acceleration at reconnection events or compressions is more important than shock acceleration. In addition, inner-heliosphere multiple-spacecraft observations have led to discussions of the importance of cross-field transport of cosmic rays. Finally, Voyager 1 has recently crossed a significant boundary which remains puzzling, but it seems that we now have, for the first time, an unimpeded view of galactic cosmic rays.

Speaker: Jack Jokipii

Slides jokipii-TeV_Cosmic_Rays_Heliospher_2013.pdf jokipii-TeV_Cosmic_Rays_Heliospher_2013.ppt

16:54 Heliospheric modulation of CRs

HelMod is 2D Monte Carlo propagation model of galactic cosmic rays through the Heliosphere. The model includes the effects due to the variation of solar activity during the propagation of cosmic rays from the boundary of the heliopause down to Earth’s position. The simulated spectra were found in agreement with those obtained with experimental observations carried out by BESS, AMS and PAMELA collaborations. Diffusion tensor in the frame of the magnetic field turbulence varies with time using a diffusion parameter obtained by Neutron Monitors. The parameters of the Model were tuned using data during the solar Cycle 23 and Ulysses latitudinal Fast Scan in 1995. The actual parametrization is able to well reproduce the observed latitudinal gradient of protons and the southward shift of the minimum of latitudinal intensity. The description of the model is also available online at website www.helmod.org. In helmod.org the end user can easily access a web interface to results catalog of the HelMod Monte Carlo Code. Catalog contain modulated proton flux data for a period (monthly average) between January 1990 and december 2007. Actualy tested and tuned web version of HelMod code will be presented. Web version of code will allow user to run simulation directly for selected set of parameters and by user choosen or imported shape of the local interstellar spectra.

Speaker: Pavol Bobik

Slides Bobik_Los_Angeles_2013_v5.pdf

17:18 Constraints on Galactic Cosmic-Ray Origins from Elemental and Isotopic Composition Measurements

The most recent measurements by the Cosmic Ray Isotope Spectrometer (CRIS) aboard the Advanced Composition Explorer (ACE) satellite of ultra-heavy cosmic ray isotopic and elemental abundances will be presented. A range of isotope and element ratios, most importantly 22Ne/20Ne and 31Ga/32Ge show that the composition is consistent with source material that is a mix of ~80% ISM (with Solar System abundances) and 20% outflow/ejecta from massive stars. In addition, our data show that the ordering of refractory and volatile elements with atomic mass is greatly improved when compared to an ~80%/20% mix rather than pure ISM, that the refractory and volatile elements have similar slopes, and that refractory elements are preferentially accelerated by a factor of ~4. We also discuss recent gamma-ray measurements and show the complementary nature of gamma- and cosmic-ray measurements. We conclude that these data are consistent with an OB association origin of GCRs.

Speaker: Walter Binns

Slides Binns-TeVPA-2013.pdf

17:42 Measuring Antimatter over Antarctica: Results from the BESS-Polar Program

The US-Japan BESS-Polar Collaboration (Balloon-borne Experiment with a Superconducting Spectrometer – Polar) has finalized its core program of elementary particle measurements. The measured antiproton spectrum probes possible exotic sources, such as dark-matter candidates. The search for antihelium or heavier antinuclei examines the possibility that antimatter domains remain in the cosmological neighborhood from symmetry breaking processes in the early Universe. Since1993, BESS has carried out eleven high-latitude balloon flights, including two long-duration Antarctic flights, that together have defined the study of antiprotons below 4 GeV, provided standard references for light element and isotope spectra, and set the most sensitive reported limits on the existence of antideuterons and antihelium. BESS-Polar II recorded over 4.7 billion cosmic-ray events in 24.5 days of flight over Antarctica during the 2007–2008 Austral Summer, identifying about 8000 antiprotons. These data more than doubled all earlier BESS flights combined and were obtained at very low, near minimum, Solar activity when the low-energy antiproton measurements are most sensitive to a primary source. Depending on energy range, the BESS-Polar II antiproton measurements have 10-20 times the statistics of BESS95+97 data from the previous Solar minimum. Here, we give an overview the scientific results of the long-duration flights of BESS-Polar I (2004) and BESS-Polar II, including antiproton and proton spectra, the energy-dependent ratios of antiprotons to protons, light isotope measurements, and the limits on the relative abundance of antihelium. We also discuss the future of the BESS-Polar program.

Speakers: Akira Yamamoto, John Mitchell

Slides Mitchell_TeVPA_BESS_Polar.pdf

18:06 The PAMELA Experiment: Seven Years of Cosmic Rays Investigation

The seven years of data taking in space of the experiment PAMELA are showing interesting features in cosmic rays, namely in the antiparticle components that can be interpreted in terms of dark matter annihilation or pulsar contribution. Moreover, precise particle spectra measurements protons, helium nuclei, electrons, made by PAMELA are challenging our basic vision of the mechanisms of production, acceleration and propagation of cosmic rays in the galaxy. PAMELA is also searching for primordial antinuclei (anti-helium), and testing acceleration and propagation models through precision studies of light nuclei and their isotopes. This talk illustrates the most recent scientific results obtained by the PAMELA experiment.

Speaker: Mirko Boezio

Slides Boezio_2013.pdf

16:30 → 18:30 High-energy neutrino

Conveners: Elisa Resconi (Technische Universität München), Kara Hoffman (University of Maryland)

16:30 Analysis of the High-Energy Starting Events in IceCube

Speaker: Claudio Kopper

Slides Kopper_-_TeVPA_HESE_technical.pdf

16:54 Demystifying the PeV Cascades in IceCube: Less (Energy) is More (Events)

The IceCube neutrino observatory has detected two cascade events with energies near 1 PeV. Without invoking new physics, we analyze the source of these neutrinos. We show that atmospheric conventional neutrinos and cosmogenic neutrinos (those produced in the propagation of ultra-high- energy cosmic rays) are strongly disfavored. For atmospheric prompt neutrinos or a diffuse back- ground of neutrinos produced in astrophysical objects, the situation is less clear. We show that there are tensions with observed data, but that the details depend on the least-known aspects of the IceCube analysis. Very likely, prompt neutrinos are disfavored and astrophysical neutrinos are plausible. We demonstrate that the fastest way to reveal the origin of the observed PeV neutrinos is to search for neutrino cascades in the range below 1 PeV, for which dedicated analyses with high sensitivity have yet to appear, and where many more events could be found.

Speaker: Ranjan Laha

Slides Laha_TeVPA_2013.pdf

17:18 Performance of the ARIANNA Neutrino Telescope

Part of a new generation of neutrino telescopes, the ARIANNA experiment uses low noise, low power and inexpensive technology to search for extremely high energy cosmic neutrinos. The telescope measures the intense radio pulse emitted by the charged particle showers resulting from neutrino interactions in the Ross Ice Shelf of Antarctica. Four stations have been installed in the ice to take both environmental as well as radio pulse data. The stations are powered by solar and wind generators, and data is sent north via wireless Internet and satellite modem peripherals. The performance of the stations will be discussed, and first results from data taken in Antarctica will be presented. The effectiveness of the Ross Ice Shelf as a radio quiet environment will be examined, the angular precision of the detector will be explored and a first search for neutrino events will be described.

Speaker: Corey Reed

Slides REED_Arianna_TeVPA2013.pdf

17:42 Reconstructing Askaryan Electric Fields in ARIANNA

The Antarctic Ross Ice Shelf Antenna Neutrino Array (ARIANNA) is an ultra-high energy neutrino detector currently under construction in Moore's Bay, in Western Antarctica. ARIANNA is designed to trigger upon and digitize GHz radio-frequency (RF) pulses created by neutrino interactions, via the Askaryan effect. In order to reconstruct the distinctive shape of this electric field, the time-domain response of both the deployed log-periodic radio antennas, and the RF amplifiers, must be quantified. Extensive, three-dimensional impulse response data was taken at the anechoic chamber at the University of Kansas, with the goal of understanding how the incident electric field is converted to a voltage waveform in the ARIANNA system. The first results for the antenna and amplifier response functions will be presented, along the primary direction of radiation of the antenna. Additionally, the angular dependence of the response function will be discussed.

Speaker: Jordan Hanson

Slides Hanson_TeVPA2013_ARIANNA.pdf

18:06 PRIDE – Passive Radio Ice Depth Experiment - An Instrument to Measure Outer Planet Lunar Ice Depths from Orbit using Neutrinos

We describe a novel application of extreme high energy neutrino detection: a concept for an instrument to measure the thickness of the ice shell on a planetary body, such as Jupiter’s moon Europa, by making use of the Askaryan Effect RF signal from EHE neutrinos. Unlike the current most often considered approach to measuring outer planetary moon ice sheet thickness, a large high powered active ice-penetrating radar, such an instrument would be a passive receiver of the naturally occurring signal generated by interactions of deep penetrating EHE neutrinos. It is therefore potentially less massive and requires less power, making it very attractive for interplanetary missions. We discuss the basic concept and consider the instrument design requirements from the perspective of a NASA Outer Planet Orbiter Mission. We show results [1] of simulations, compare signal-to-noise estimates, and examine possible components and configurations for the antenna, receiver, and electronics. We note some options that can be used to reduce mass and power. Finally, we identify issues that would need further study to produce a more concrete design.

Speaker: Tim Miller

Slides Miller.pdf

18:30 → 20:00 Reception

Tuesday, 27 August

07:00 → 08:30 Breakfast

08:30 → 10:30 Plenary

08:30 Auger

Speaker: Markus Roth (Forschungszentrum Karlsruhe)

Slides Roth_Auger.pdf

09:00 Results from the Telesope Array Experiment

The Telescope Array (TA) is the largest ultrahigh energy cosmic ray detector in the northern hemisphere. The experiment consists of three fluorescence stations viewing the air space over a surface array of 503 scintillation counters deployed over 700 square kilometers. TA has been in operation since 2008. The results from TA will be presented, along with a brief report on the progress of the new TA low energy extension (TALE).

Speaker: Charles Jui

Slides Jui-ta-tevpa2013.pdf

09:30 What can we learn about the ultra-high energy cosmic-ray origin from the present results by the IceCube Neutrino Observatory?

Speaker: Shigeru Yoshida (Chiba University)

Slides Yoshida_IceCubeTellsOriginOfUHECRs.pdf

10:00 Radio Askaryan Neutrino Telescopes

There are strong motivations for a detectable flux of ultra-high energy (UHE) cosmic neutrinos above 10$^{17-18}$~eV both from cosmic ray interactions with cosmic microwave background photons and directly from UHE sources. The radio Cerenkov technique is the most promising technique for instrumenting a detection volume large enough to detect the low expected fluxes, and so far all experiments in the field use Antarctic ice as their detection medium due to its immense volume and clarity at radio/microwave frequencies. All current and future projects either view the ice using antennas flown at high altitudes, or use antennas embedded in the ice itself. The world's best constraints on neutrino fluxes above 10^18 eV come from RICE, embedded in the ice near the South Pole, and ANITA, a balloon-borne experiment that is launched under NASA's long duration balloon program. I will review the status of past and current experiments in the field, as well as current and future experiments ARA, ARIANNA and EVA. I will also touch on the implications of future UHE neutrino measurements for particle physics and particle astrophysics.

Speaker: Amy CONNOLLY

Slides Connolly_TeVPA.pdf

10:30 → 11:00 Coffee Break

11:00 → 12:30 Plenary

11:00 Recent results from the AMS-02 experiment

Speaker: Veronica Bindi (University of Hawaii)

Slides Bindi_UCI.pdf

11:30 CREAM

Speaker: Eun-Suk Seo (University of Maryland)

Slides Seo_TeVPA2013_CREAM_Seo.pdf

12:00 Probing Galactic Cosmic Ray Origins with the SuperTIGER Long-Duration Balloon Instrument

The SuperTIGER (Super Trans-Iron Galactic Element Recorder) long-duration balloon instrument was developed by Washington University in St. Louis, NASA Goddard Space Flight Center, Caltech, Jet Propulsion Laboratory, and the University of Minnesota to measure the abundances of galactic cosmic ray elements from 26Fe to 40Zr with high statistics and single element resolution, and to extend exploratory measurements to about 60Nd. SuperTIGER launched from Williams Field, McMurdo Station, Antarctica, on December 8, 2012 and made over 2.5 revolutions around the continent, flying for a record 55 days and returning data on over 50 million heavy cosmic ray nuclei. The instrument, the methods of charge identification employed, and preliminary results from the SuperTIGER I balloon flight will be presented. SuperTIGER measurements will be discussed in context of their stringent tests of the OB association model for the origin of galactic cosmic rays. The recent Fermi gamma-ray observations, which have shown that protons are accelerated from supernova remnants, will also be discussed in the context of the OB association model. Finally, planned improvements to the SuperTIGER instrument and future flight plans will be described.

Speaker: John Mitchell (NASA)

Slides Mitchell_TeVPA_2013_SuperTIGER.pdf

12:30 → 14:00 Lunch Break

14:00 → 16:00 High-energy cosmic rays and their propagation

Conveners: Igor Moskalenko (Stanford), Mirko Boezio (INFN Trieste), Rene Ong (UCLA)

14:00 Propagation of cosmic rays

The theoretical aspects of cosmic ray transport in the Galaxy are discussed. Discussion includes the interpretation of data on cosmic ray spectrum, composition and anisotropy. The model of cosmic ray origin in supernova remnants, the nature of “knee” in cosmic ray spectrum at energy 3 PeV, and the collective effects of cosmic rays in the Galaxy are considered.

Speaker: Vladimir Ptuskin

Slides Ptuskin_UCI_2013.pdf

14:24 Brief review of ATIC results on nuclei and electrons

The Advanced Thin Ionization Calorimeter (ATIC) experiment had a test flight and two science flights from McMurdo, Antarctica, in addition to a beam calibration at CERN. The experiment, designed to measure the spectra of H, He and heavy nuclei, was also capable of separating electrons from protons. The development and history of ATIC is briefly reviewed as a context for presenting the measured spectra of cosmic rays, including total electrons, in the very high energy regime.

Speaker: John Wefel

Slides Wefel_ATIC_Irvine_2013.pdf

14:48 Cosmic Rays with VERITAS

VERITAS is an array of four imaging atmospheric Cherenkov telescopes in southern Arizona and is one of the world's most sensitive detectors of very high energy (VHE: >100 GeV) gamma rays and cosmic rays. While the primary focus of VERITAS is to detect and understand gamma-ray sources, techniques can be developed to distinguish and measure individual cosmic-ray species in the data. In this talk we'll survey the status of VERITAS measurements of cosmic rays--including progress towards an all-electron spectrum, prospects for the measurement of the positron fraction, and work towards distinguishing high-Z particle species with a direct Cherenkov technique. We'll also discuss recent VERITAS gamma-ray results that are directly relevant to the propagation of cosmic rays.

Speaker: David Staszak

Slides Staszak_TeVPA2013_v2.pdf

15:12 Cosmic Ray Studies with MAGIC

Galactic sources of cosmic rays might be gamma ray emitters, if interactions of cosmic ray protons and nuclei yielding high energy photons occur in the source ambient. In the very high energy regime, photons can be detected with the Cherenkov Imaging technique through the light produced by their extensive air showers in the atmosphere. MAGIC is a system of two such imaging air Cherenkov telescopes situated on the Canary island of La Palma. The MAGIC collaboration has performed several observations of galactic sources, including supernova remnants, X-ray binaries, pulsars, pulsar wind nebulae, as well as a search for diffuse cosmic ray electrons and positrons. A special focus was placed on observations of supernova remnants embedded in molecular clouds, which are promising sites for detecting the gamma ray production from cosmic ray interactions. Here we report on the status of this projects and highlight recent results.

Speaker: Sara Rebecca Gozzini

Slides Gozzini_cosmic_ray_studies_with_magic.pdf

15:36 PeV Cosmic Rays measured by IceCube/IceTop

We report on the high-resolution measurements of cosmic ray spectrum and mass composition from the knee region up to 1 EeV based on one year of data collected with IceCube/IceTop. Complementary to the PeV neutrinos, IceCube measures extensive air showers of PeV cosmic rays on the surface with the IceTop array and the penetrating high energy muon bundles with the matrix of detectors in deep ice. The measured spectrum can not be explained by a simple power law beyond the knee, which confirm the other recent measurements (GAMMA, Tunka, Kaskade-Grande). We observe a prominent hardening above 18 +/- 2 PeV followed by a sharp steepening beyond 130 +/- 30 PeV. The composition gets heavier and heavier up to at least 130 PeV as indicated by the steady increase in the measured mean logarithmic mass. The change in shape and amplitude of anisotropy observed by IceCube/IceTop in the arrival direction distributions of cosmic rays at PeV energies will also be discussed.

Speaker: Serap Tilav

Slides Tilav_PeVCRs-IceTop-at-TeVPA.pdf TIlav_SpectralBreaks.pdf

14:00 → 16:00 Ultra-high-energy messengers

Conveners: Ignacio Taboada (Georgia Tech), Markus Ahlers (University of Wisconsin-Madison)

14:00 Extreme Energy Particles with JEM-EUSO

The origin of the highest energy cosmic rays is still a great mystery. Recent observations have confirmed the extragalactic origin of cosmic rays above tens of EeV, whose sources should be among the most powerful extragalactic objects. The spectrum shows the effect of propagation from cosmological distances or possibly the maximum energy reach of cosmic accelerators. The lack of significant anisotropies and a possible change of composition are surprising. Not a single source of these extremely energetic events has been identified. To identify the sources a significant increase in statistics is necessary. The pioneering Extreme Universe Space Observatory (EUSO) on the Japanese Experiment Module (JEM) of the International Space Station, JEM-EUSO, will detect a large number of extreme energy cosmic rays finally leading to a identification of these mysterious extreme accelerators.

Speaker: Angela Olinto

Slides Olinto_JEMEUSO.pdf

14:30 Measuring Potential Noise Backgrounds for the Telescope Array Radar (TARA) near Long Ridge, UT

The main transmitter and receiver stations for the Telescope Array Radar bi-static cosmic ray detection system are now complete. To perform background-free coincidence studies, low-cost , sustainable power remote stations are being designed and built. A site survey was conducted in March 2013 with the goal of finding a remote site in the desert near the main TARA receiver at Long Ridge, UT. The two main goals were to locate a site with little or no radio backgrounds, and a site that was within range of the 40 kW TARA transmitter. A collection of possible future sites were located, and monte carlo simulations were performed which indicate that there is little cost to signal sensitivity by placing a detector at any of these sites. The remote station concept, noise data, and monte carlo analysis will all be presented.

Speaker: Jordan Hanson

Slides Hanson_TeVPA2013_TARA.pdf

15:00 The development of remote receiver stations for TARA

The development remote receiver stations for TARA The Telescope Array RAdar (TARA) detector is based on a remote sensing technique known as bi-static radar that aims to achieve remote coverage over large portions of the Earth's surface in search of cosmic ray induced radio echoes. In conjunction with North America's largest cosmic ray observatory (The Telescope Array) in radio quiet western Utah, the radar project's pilot receiver and transmitter stations have been functional for just about two years, giving insight into the detect-ability of air shower radar echoes. Currently the receiver stations comprise an array of Log Periodic Dipole Antennas and among others an oscilloscope-based data acquisition system implemented for noise calibration. Our experiences thus far have given impetus for upgrades, including the deployment of solar and wind powered remote receiver stations. We discuss the development of these remote stations including the implementation of a down - conversion technique to detect the cosmic ray induced radio echoes.

Speaker: Samridha Kunwar

Slides Kunwar_TevPa_2013.pdf

15:30 Anisotropy studies with the Pierre Auger Observatory

Anisotropy studies with the Pierre Auger Observatory The Pierre Auger Observatory in Argentina measures air showers initiated by cosmic rays at EeV energy scales and above. An important goal of the collaboration is to study the distribution of arrival directions of the primary particles and quantify potential anisotropies. Recent results from anisotropy searches using data collected with the Pierre Auger Observatory will be presented. These include a search for a large scale dipolar anisotropy pattern, a search for localized excesses of cosmic ray neutrons, the search for multiplets of aligned events, and an update on the search for correlations between events with energy above 55 EeV and the positions of active galactic nuclei.

Speaker: Miguel Mostafa

Slides Mostafa_Auger-Anisotropy.pdf

16:00 → 16:30 Coffee Break

16:30 → 17:42 Particle physics

Conveners: Enectali Figueroa (MIT), Enectali Figueroa (MIT), Mariangela Lisanti (Princeton), Mariangela Lisanti (Princeton), Roni Harnik (Fermilab), Roni Harnik (Fermilab), Xiaojun Bi (IHEP, China), Xiaojun Bi (IHEP, China)

16:30 Electroweak Cogenesis

We propose a simple renormalizable model of baryogenesis and asymmetric dark matter generation at the electroweak phase transition. Our setup utilizes the two Higgs doublet model plus two complex gauge singlets, the lighter of which is stable dark matter. The dark matter is charged under a global symmetry that is broken in the early universe but restored during the electroweak phase transition. Because the ratio of baryon and dark matter asymmetries is controlled by model parameters, the dark matter need not be light. Thus, new force carriers are unnecessary and the symmetric dark matter abundance can be eliminated via Higgs portal interactions alone. The dark matter mass is also constrained within a window around the weak scale. One of the main predictions of this model is CP violating Higgs signals at the LHC and future colliders.

Speaker: Yue Zhang

Slides Zhang_TeVPA_yuezhang.pdf

16:54 Self-interacting dark matter in a non-abelian hidden sector

N-body simulations of collisionless cold dark matter seem to disagree with observations on small scales, suggesting that the properties of dark matter are much richer than the conventional picture. A promising solution is self-interacting dark matter with a cross section over mass of 0.1 to 1 cm^2/g, which is able to bring simulations in line with observations over a wide range of astrophysical scales and not ruin large-scale structure. Motivated by these results, we construct a particle model of dark matter that has the cross sections needed to explain structure while still yielding the measured cold dark matter relic abundance. We consider dark matter charged under a hidden SU(N) gauge and work in the context of anomaly-mediated supersymmetry breaking to automatically set the correct abundance. Confinement occurs prior to structure formation, and the resulting composite particles strongly interact to yield large scattering cross sections. We discuss the difficulties of a secluded hidden sector and options for communication with the Standard Model.

Speaker: Boddy Kimberly

Slides boddy-TeVPA-2013.pdf

17:18 Particle Physics Implications and Constraints on Dark Matter Interpretations of the CDMS Signal

Recently the CDMS collaboration has reported an excess of events in the signal region of a search for dark matter scattering with Silicon nuclei. Three events on an expected background of 0.4 have a significance of about 2 sigma, and it is premature to conclude that this is a signal of dark matter. Nonetheless, it is important to examine the space of particle theories capable of explaining this excess, to see what theories are capable of explaining it, and how one might exclude it or find corroborating evidence in other channels. We examine a simplified model containing a scalar mediator particle, and find regions consistent with the CDMS observations. Bounds from colliders put important restrictions on the theory, but viable points, including points leading to the observed thermal relic density, survive.

Speaker: Alexander Wijangco

Slides Wijangco_TEVPA.pdf

16:30 → 18:30 Ultra-high-energy messengers

Conveners: Ignacio Taboada (Georgia Tech), Markus Ahlers (University of Wisconsin-Madison)

16:30 Mass composition studies with Pierre Auger Observatory

Mass composition studies with Pierre Auger Observatory The study of the mass composition of cosmic rays is important to understand their origin. At ultra-high energies, the primary mass can only be estimated from the shower observables. These include the depth of maximum of the longitudinal shower development, Xmax, and different observables measured with the surface detector array such as the production depth distribution of muons. Pierre Auger Observatory allows the direct measurement of Xmax with its fluorescence telescopes and the muon production depth can be derived indirectly from the particle arrival time distribution at ground. In this talk we will introduce the analysis steps for measureing Xmax and present recent results on the mean value of Xmax and its shower-to-shower fluctuations. In the second part of the talk we will compare these results with estimates of the mass composition using the surface detector data of the observatory.

Speaker: Alessio Porcelli

Slides Porcelli_2013_08_27_AugerMassComposition.pdf

17:00 Measurements of the muon content of air showers and search for ultra-high energy neutrinos and photons at the Pierre Auger Observatory

The Pierre Auger Observatory offers a unique window to study cosmic rays and particle physics at energies above 3 EeV (corresponding to a center-of-mass energy of 75 TeV in proton-proton collisions) inaccessible to accelerator experiments. We discuss the different methods of estimating the number of muons in showers recorded at the Surface Detector array, which is an observable sensitive to primary mass composition and to properties of the hadronic interactions in the shower. The muon content, derived from data with these methods, is presented and compared to predictions from the post-LHC hadronic interaction models. In the light of observed Xmax distribution being incompatible with an iron dominated composition, we conclude the observed number of muons is not well reproduced by the shower simulations. We also present the latest results on the search of UHE neutrinos and photons in the EeV range, reporting updated upper limits on the diffuse flux of ultra-high energy neutrinos and new upper limits on regularly emitting non-beamed photon sources in the Galaxy.

Speaker: Ines Valino

Slides Valino_TeVPA2013_NeutrinosPhotonsMuons_PierreAuger.pdf

17:30 Probing cosmic-ray origin with the cosmogenic neutrino searches with IceCube

IceCube is a cubic kilo-meter scale, deep-ice Cherenkov neutrino detector at the South Pole. IceCube's high energy neutrino searches cover an energy region of the TeV and lower energies, and also the much higher energy region up to EeV and higher. In the EeV energy region, cosmogenic neutrinos channelled from ultra-high energy cosmic-ray emissions which play leading roles in the flow of astrophysical energies are expected. While cosmic-rays and gamma-ray photons rapidly loose their energies in the ultra-high energy region via the interaction with the cosmic microwave background, cosmogenic neutrinos remember the history of the ultra-high energy emission activity since the era when the Universe was young because neutrinos can travel long distance regardless of their energy. The analysis of 2 years of IceCube data taken in the period between May 2010 and May 2012 in search for ultra-high energy neutrinos was conducted. Two events with approximately 1 PeV were observed from the analysis. No observation of events in higher energies allows to place the tightest upper limit to date on the neutrino flux in the energy region from PeV to 10EeV. In this talk the results from the cosmogenic neutrino search with IceCube are presented and their implication is discussed.

Speaker: Aya Ishihara

Slides IshiharaGZKIceCube-TeVPAPresented.pdf

18:00 Neutrino transport in accretion disks

Gamma-ray bursts (GRBs) are one of the most violent explosions in our universe. Even though the fireball-shock model succeeds in explaining the multi-wavelength emission from the afterglow of GRBs, we have not known what is the central engine of GRBs. The generally accepted model for the central engine of GRBs is believed to be related to the hyperaccretion of a stellar-mass black hole at extremely high rates, such as one solar mass per second! In such an accretion disk, matter is so dense that photons are trapped. The possible channel for energy release is neutrino emission, so this model is so-called Neutrino-Dominated Accretion Flow (NDAF). In this talk, I will give a brief introduction to our recent works on neutrino/anti-neutrino transport in NDAF, its influence on the dynamics of NDAF and the luminosity of neutrino annihilation. Our main concern is to check whether the released energy could power the fireball. We find that the annihilation luminosity is sensitive to the accretion rate and will be not sufficient to power the fireball of most energetic GRBs if the accretion rate is lower than 1 solar mass per second. Therefore, the effects of the spin of the black hole or/and the magnetic field in the accretion flow might play a role in powering the central engine of GRBs.

Speaker: Ye-Fei Yuan (Univ. of Sci. and Tech. of China)

Wednesday, 28 August

07:00 → 08:30 Breakfast

08:30 → 10:30 Plenary

08:30 Galactic GeV overview

Speaker: Terri Brandt (NASA)

Slides Brandt_2013.pdf

09:00 Galactic TeV overview

Speaker: Emma De Ona Wilhelmi (ICE, Spain)

Slides Wilhelmi_2013.pdf

09:30 Extragalactic gamma-ray overview

Speaker: Yoshiyuki Inoue (SLAC)

Slides inoue_TeVPA.pdf

10:00 The High Altitude Water Cherenkov Observatory

The High Altitude Water Cherenkov (HAWC) observatory, under construction in Central Mexico at an altitude of 4,100m, will consist of 300 large light-tight water tanks instrumented with photomultiplier tubes. Ground level particles produced by gamma rays and cosmic rays that collide with the upper atmosphere are detected with these tanks. HAWC differentiates gamma-ray and cosmic-ray primaries by identifying muons as a part of the air showers. HAWC will be a prime survey instrument in the 100 GeV - 100 TeV energy range with 2 sr instantaneous field of view and >95% duty cycle. In this presentation I will discuss construction and operation status and preliminary results on the observation of the moon's and sun's shadow with cosmic rays as well as the Crab nebula. I will also summarize prospects for detections of supernovae remnants, diffuse galactic sources, active galactic nuclei, gamma-ray bursts, etc.

Speaker: Ignacio Taboada (Georgia Tech)

Slides Taboada_TeVPA_HAWC.pdf

10:30 → 11:00 Coffee Break

11:00 → 12:30 Plenary

11:00 Cosmic ray propagation

Speaker: Troy Porter (Stanford University)

Slides Porter_CRsandDiffuseEmission_irvine_Porter.odp Porter_CRsandDiffuseEmission_irvine_Porter.pdf

11:30 Indirect detection of dark matter: gamma-ray overview I

Speaker: Robert Johnson (UC Santa Cruz)

Slides Johnson_TeVPA2013_RPJ.pdf

12:00 Indirect detection of dark matter: gamma-ray overview II

Speaker: Savvas Koushiappas (Brown University)

12:30 → 14:00 Lunch Break

14:00 → 16:00 High-energy cosmic rays and their propagation

Conveners: Igor Moskalenko (Stanford), Mirko Boezio (INFN Trieste), Rene Ong (UCLA)

14:00 Cosmic Ray Electron Synchrotron Telescope (CREST) status report

The CREST instrument aims to determine whether cosmic electrons are seen at Earth beyond a few TeV, from sources in the local Galactic neighborhood (a kpc or so). Only a few candidate astrophysical sites exist that meet the acceleration and propagation requirements, such as the Vela, Monogem, and Cygnus Loop remnants, and thus multi-TeV electrons are a useful marker of the nearby high energy universe. CREST is flown by high-altitude ballon in Antarctica and detects electrons through their geosynchrotron x-ray emissions in the South polar regions of the Earth. The signature is a stream of x-ray photons emitted in the plane of electron travel, intersecting the plane of a horizontal detector array; the net effect is a co-linear arrangement of x-ray hits coincident in time. CREST comprises an array of 1024 BaF2 crystal detectors, surrounded by veto plastic scintillators to guard against chance alignments of charged particles in air showers. This instrument was successfully launched from McMurdo Station in Antarctica on December 25, 2011, and flew for 10 days. Analysis of the flight data requires a comprehensive understanding of backgrounds from nuclear cosmic rays and atmospheric air shower particles, as well as the effect of the geomagnetic field throughout the circumpolar flight trajectory. To this end, detailed background simulations are carried out based on the GLAST/Fermi physics model, and a full GEANT4 simulation of the CREST payload. A status update of the analysis of the data from the maiden flight of the CREST instrument will be presented.

Speaker: Stephane Coutu

Slides Coutu_CREST_TeVPA2013_posted.pdf

14:24 The Calorimetric Electron Telescope (CALET) for High Energy Astroparticle Physics on the International Space Station

The CALET space experiment, currently under development by Japan in collaboration with Italy and the United States, will measure the flux of Cosmic Ray electrons (and positrons) to 20 TeV, gamma rays to 10 TeV and nuclei with Z=1 to 40 up to 1,000 TeV during a five year mission. These measurements are essential to investigate possible nearby astrophysical sources of high energy electrons, study the details of galactic particle propagation and search for dark matter signatures. The instrument consists of a module to identify the particle charge, a thin imaging calorimeter (3 radiation lengths) with tungsten plates interleaving scintillating fiber planes, and a thick calorimeter (27 radiation lengths) composed of lead tungstate logs. CALET has the depth, imaging capabilities and energy resolution necessary for excellent separation between hadrons, electrons and gamma rays. The instrument is currently being prepared for launch, during the 2014 time frame, to the International Space Station (ISS) for installation on the Japanese Experiment Module – Exposure Facility (JEM-EF).

Speaker: Shoji Torii

Slides Torii_TeVPA-pub.pdf

14:48 The DAMPE Space Mission

DAMPE (DArk Matter Particle Explore) is a satellite mission of the Chinese Academy of Science dedicated to high energy particle detections in space. The main scientific objective of DAMPE is to detect electrons and photons in the range of 5 GeV-10 TeV with unprecedented energy resolution in order to identify possible Dark Matter signatures. It will also measure the flux of nuclei up to 100 TeV with excellent energy resolution, which will bring new insights to the origin and propagation high energy cosmic rays. With it's excellent photon detection capability, the DAMPE mission is also well placed for new discoveries in high energy gamma astronomy. The DAMPE detector consists of a plastic scintillator strips detector (PSD) that serves as anti-coincidence detector, a silicon-tungsten tracker-converter (STK),a BGO imaging calorimeter of about 31 radiation lengths, and a neutron detector. In this talk the science goals, the design, the expected performance and the detector construction status will be presented.

Speaker: Xin Wu

Slides Wu_TevPar2013-Dampe-XWu-talk.pdf

15:12 Cosmic ray physics with the GAMMA-400 experiment

GAMMA-400 is a future high-energy gamma-ray telescope, primarily devoted to the study of gamma-rays in the 50 MeV - 10 TeV energy range. Thanks to a deep segmented calorimeter of novel concept and a state-of-the-art imaging Silicon Tracker, the proposed instrument has an optimal proton rejection factor, angular and energy resolution. The GAMMA-400 experiment is optimized to address a broad range of science topics, such as search for signatures of dark matter, studies of galactic and extragalactic gamma-ray sources, galactic and extragalactic diffuse emission, gamma-ray bursts, as well as high precision measurements of high energy electrons flux up to TeV energies, and spectra of protons and nuclei up to 10^15-10^16 eV/nucleon. GAMMA-400 is planned to be launched on the Russian space platform Navigator in 2018.

Speaker: Paolo Cumani

Slides Cumani_G400-TeVPA_cumani.pdf

15:36 Results From the pGAPS Test Flight

The General Antiparticle Spectrometer (GAPS) experiment is a proposed dark matter indirect-detection mission intended to fly on an Antarctic scientific balloon later this decade. GAPS will search for low energy (<300 MeV/n) cosmic ray antideuterons. A number of theoretical WIMP dark matter candidates are predicted to produce enhancements in the flux of antimatter particles in Galactic cosmic rays. Searches for excesses in the antiproton and positron spectra are ongoing but are difficult to interpret because of large backgrounds from secondary production. Cosmic ray antideuterons are expected to have a much smaller relative background, and at lower energies the flux is especially sensitive to a dark matter contribution. In June of 2012 a prototype GAPS experiment (pGAPS) was flown from Hokkaido, Japan to validate the crucial components and techniques needed to build and operate a full-scale GAPS experiment. The flight was a full success and lasted for 6 hours (over 3 hours at float altitude), with over 1 million cosmic ray triggers recorded. Results from the flight will be presented, as well as the status of preparations for the full-scale GAPS science mission.

Speaker: Isaac Mognet

Slides Mognet_GAPStalkTevPA.pdf

14:00 → 16:00 Indirect searches for dark matter

Conveners: Carsten Rott (Sungkyunkwan University), Tracy Slatyer (MIT)

14:00 The VERITAS Dark Matter Program

In the cosmological paradigm, cold dark matter (DM) dominates the mass content of the Universe and is present at every scale. Candidates for DM include many extensions of the standard model, with a weakly interacting massive particle (WIMP) in the mass range from 50 GeV to greater than 10 TeV. The self-annihilation of WIMPs in astrophysical regions of high DM density can produce secondary particles including very high energy (VHE) gamma rays with energy up to the DM particle mass. VERITAS, an array of atmospheric Cherenkov telescopes, sensitive to VHE gamma rays in the 85 GeV-30 TeV energy range, has been utilized for the indirect detection of DM. The possible astrophysical objects considered to be candidates for indirect DM detection are VERITAS dwarf spheroidal galaxies (dSphs) of the Local Group, the Galactic Center among others. This presentation reports on our extensive observations of these targets and constraints of the dark matter physics from these objects.

Speaker: Benjamin Zitzer

Slides Zitzer_TeVPA2013_DM.pdf

14:20 Constraints on dark matter annihilation and decay in the Milky Way halo

Constraints on dark matter annihilation and decay in the Milky Way halo Indirect DM searches through gamma rays produced in DM annihilation/decay in the Milky Way halo are promising means to test the WIMP paradigm due to the high DM density in the inner Galaxy and proximity of the target. Propagation of Galactic cosmic rays also produces diffuse gamma rays which represent a major foreground for these searches. In this talk we report results of an analysis in which we test the Fermi-LAT diffuse data for a contribution from a DM annihilation/decay signal by marginalizing over several parameters that determine the contribution from cosmic-ray-induced diffuse gamma-ray emission. We present competitive constraints on the DM annihilation cross section and decay lifetime for several DM channels and discuss an improved treatment of the uncertainties due to the DM density profile.

Speaker: Gabrijela Zaharijas

Slides Zaharijas_DMhalo.pdf

14:40 Dark Matter constraints from Fermi-LAT inner Galaxy measurements

We derive stringent constraints on parameters of generic dark matter candidates in the likely case that the collapse of baryons to the Galactic Center is accompanied by the contraction of the dark matter. By comparing theoretical predictions with the gamma-ray emission observed by the Fermi-LAT from the region around the Galactic Center, we find that for all the annihilation channels studied, the upper limits on the annihilation cross section imply that the thermal cross section is excluded for a large range of dark matter mass. Our analysis is conservative since it simply requires that the expected dark matter signal does not exceed the observed gamma-ray emission by the Fermi-LAT in optimized regions around the Galactic Center. The upper limits on the annihilation cross section of dark matter particles obtained are two orders of magnitude stronger than without contraction. In the latter case our results are compatible with the upper limits previously reported by the Fermi-LAT collaboration, where the thermal cross section is not excluded after analyzing the Galactic halo with the same conservative approach without modeling of the astrophysical background.

Speakers: German Gomez Vargas, Miguel SANCHEZ-CONDE

Slides Gomez_DM_GC_contracted_UCI_V1_TEVPA13.pdf

15:00 The 135 GeV Fermi Line and MiDM/RayDM at the LHC

Abstract: Magnetic and Rayleigh dark matter (MiDM/RayDM) are models describing weak interactions of dark matter with photons through non-renormalizable operators. Such operators motivate the existence of heavier states that couple to dark matter and are also charged under the electroweak interactions. The recent hints of a gamma ray line in the Fermi data suggest that these states may be light enough to be produced at the LHC. We categorize such states according to their charges and decay modes, and examine the corresponding LHC phenomenology, emphasizing unconstrained models that can be discovered in targeted searches at the upgraded LHC run, while also enumerating models excluded by current data. We propose searches to constrain models allowed by current LHC bounds, including models with multiple tau lepton and gauge boson final states, and in particular find superior performance for our methods over existing proposals for multi-tau analyses.

Speaker: Brian Shuve

Slides Shuve_TeVPA.pdf

15:20 Indirect Search for Light Dark Matter with X-rays

I summarize the constraints placed on two well-motivated dark matter candidates that produce an X-ray line via radiative decay -- the sterile neutrino and moduli dark matter -- from our dedicated X-ray search for dark matter targeting dwarf spheroidal galaxies, as well as from related investigations. I also anticipate the increase in sensitivity expected to emerge from current and upcoming efforts to deepen the search utilizing stacking of existing archival data, and observations with the high energy resolution Soft X-ray Spectrometer -- the featured detector aboard the Astro-H X-ray Observatory scheduled for a 2015 launch.

Speaker: Michael Loewenstein

Slides loewenstein_TeV_PA_m.pdf

15:40 Analysis of dark matter and astrophysical interpretations for excess extended gamma ray emission in Galactic center

We place constraints on the dark matter annihilation cross section by analyzing Fermi Gamma Ray Space Telescope data from the galactic center. We arrive at both a conservative limit, including only known sources of gamma ray emission, and a more stringent model dependent limit, which includes a possible unresolved millisecond pulsar (MSP) population. We also study uncertainties introduced by the diffuse emission in the Galaxy.

Speaker: Nicolas Canac

Slides canac_TeVPA2013.pdf

16:00 → 16:30 Coffee Break

16:30 → 18:30 High-energy gamma rays

Conveners: Brenda Dingus (LANL), Justin Vandenbroucke (University of Wisconsin, Madison)

16:30 The Impact of Gamma-ray Halos on the Angular Anisotropy of the Extragalactic Gamma-ray Background

The study of the development of electromagnetic cascades in intergalactic magnetic fields (IGMF) serves as a robust probe into the strength and structure of these magnetic fields. Charged particles in electromagnetic cascades are deflected by magnetic fields giving rise to gamma-ray halos around extragalactic sources of VHE gamma rays (e.g., BL Lacertae-type objects). Such gamma-ray halos can have a profound impact on the intensity and angular properties of the contribution of extragalactic VHE sources to the extragalactic gamma-ray background (EGB) as measured by the Fermi-LAT at GeV energies. We demonstrate the impact of the deflection of cascades by the IGMF on the collective spectrum of extragalactic VHE sources, as well as the impact on the angular anisotropy of the EGB as a function of energy.

Speaker: Tonia Venters

Slides Venters_TeVPA13.pdf

16:54 The measurement of the expansion rate of the Universe from gamma-ray attenuation

The first statistically significant detection of the cosmic gamma-ray horizon (CGRH) that is independent of any extragalactic background light (EBL) model is presented in this talk. The CGRH is a fundamental quantity in cosmology. It gives an estimate of the opacity of the Universe to very-high energy (VHE) gamma-ray photons due to photon-photon pair production with the EBL. Our CGRH detection is possible thanks to a multiwavelength catalog of blazars that includes the latest data analysis from the Fermi satellite and Cherenkov telescopes. Interestingly, the observed CGRH is compatible with the current knowledge of the EBL. We show how the detection of the CGRH allow us to measure the expansion rate of the Universe from gamma-ray attenuation. The value of the Hubble constant that we derive is compatible with present-day measurements using well established methods such as local distance ladders and cosmological probes. We also discuss an observational strategy aimed to reduce the uncertainties in the Hubble constant estimate from our novel and independent technique.

Speaker: Alberto Dominguez

17:18 Constraining emission models with observations of the highest-energy gamma rays from the exceptional GRB 130427A

The prompt emission from the very bright and nearby gamma-ray burst GRB 130427A was detected by several orbiting telescopes and prompt optical emission was also detected from the ground. Observations of the afterglow emission from GRB 130427A show detections from radio to gamma-ray wavelengths and include well-sampled early afterglow lightcurves at optical and X-ray wavelengths. Apart from the intensity and proximity of this GRB, it is exceptional due to the extremely long-lived high-energy emission (HE, >100 MeV), which was detectable by the Large Area Telescope (LAT) on the Fermi satellite for nearly a full day after the initial burst. A relatively bright optical flash coupled with the persistent, hard-spectrum, HE emission suggests that the highest-energy gamma rays may have been produced via synchrotron self Compton (SSC) processes. VERITAS, a ground-based imaging atmospheric Cherenkov telescope array began follow-up observations of GRB 130427A at ~71 ks after the burst. The GRB was not detected with VERITAS, however the very high elevation of observations, coupled with the low redshift of the GRB makes VERITAS a very sensitive probe of the highest-energy emission from GRB 130427A. Results from a joint analysis of LAT and VERITAS data are presented here. These results fully cover the energy range of 100 MeV - 30 TeV and place constraints on the SSC model of high-energy gamma-ray emission from this GRB.

Speaker: Taylor Aune

Slides Aune_GRB130427ATalk_Aune.pdf

17:42 Search for high energy emission from GRBs with the HAWC Observatory

The High Altitude Water Cherenkov Observatory (HAWC) is an air shower array currently under construction in Mexico at an altitude of 4100 m. HAWC will consist of 300 large water tanks covering an area of about 22000 square meters and instrumented with 4 photomultipliers each. HAWC's primary purpose is the observation of cosmic gamma-ray sources, including large extended sources and transient phenomena. The high altitude, high duty cycle and large field of view make HAWC an excellent instrument for the detection of prompt high energy component of Gamma-Ray Bursts. With an effective area of >100 square meters at 100 GeV and improved gamma-hadron separation capabilities, HAWC will be almost two orders of magnitude more sensitive to GRBs than its predecessor Milagro. The observations (or non-observations) of GRBs by HAWC will provide important information on the high-energy spectra of GRBs. We will present the projected sensitivity of HAWC to GRBs and the results of GRB searches using the partially built HAWC array, including upper limits on high energy emission from Fermi LAT bursts 130427A, 130504C and 130702A.

Speaker: Dmitry Zaborov

Slides Zaborov_HAWC-GRB-searches.pdf

18:06 Multi-Wavelength Study of HESS J1809-193: Suzaku and Chandra Observations of the North-East Extension

Multi-wavelength observations of the HESS J1809−193 field reveal a complex picture. Although the majority of the bright TeV emission can be attributed to the pulsar-wind nebula (PWN) of PSR J1809−1917, several supernova remnants, as well as another PWN, may contribute to the observed VHE emission. The H.E.S.S. image shows an extension toward north-east, which could be a separate TeV source. We present preliminary results from three Chandra and two Suzaku observations of this region. One of the X-ray sources in the field is the low-mass X-ray binary candidate XTE J1810-189, for which we show the outburst history from multiple observatories. We present our analysis of the gamma-ray (Fermi), radio and X-ray data for this region. Preliminary multi-wavelength classification is presented for the brightest X-ray sources in the Chandra ACIS fields. We investigate whether there is any correlation between the TeV "extension" and any of the sources seen at lower energies. This research was partially supported by NASA grants NNX10AH82G, NNX09AC81G, and NASA/SAO grant GO3-14049X.

Speaker: Blagoy Rangelov

16:30 → 18:30 Indirect searches for dark matter

Conveners: Carsten Rott (Sungkyunkwan University), Tracy Slatyer (MIT)

16:30 Indirect WIMP Searches with Super-Kamiokande

A search for neutrinos from self-annihilation of Weakly Interacting Massive Particle (WIMP) in the Super-Kamiokande data resulted in no significant excess above the expected backgrounds. The derived limits are presented and compared against the results of other searches. Future prospects with large water Cherenkov detectors are discussed.

Speaker: Michael Smy

Slides smy_tevpa2013_superk.pdf

16:50 The Effective Theory of Self-Interacting Dark Matter

We present new results for self-interacting dark matter focusing on applications to Sommerfeld enhancement. We provide the general parameterization of the self interactions in terms of non-relativistic operators and show how these can generate singular potentials. We show how to consistently renormalize such singular potentials and give bounds on the resulting enhancement. This procedure can be used to give a velocity dependent cross section and can be applied to small scale astrophysical anomalies such as the core vs. cusp problem.

Speaker: Mathieu Cliche

Slides Cliche_EffectiveTheorySIDM.pdf

17:10 Cold dark matter halo concentrations and their implications for substructure annihilation boosts

In the standard cosmology, there exists a strong connection between the internal structural properties of dark matter (DM) halos and their formation epochs. Such information can be expressed in terms of a single key parameter known as concentration. We compute the natal halo concentrations that naturally arise in the model by Prada et al. (2012), which links the concentration with the r.m.s. of the matter fluctuations. We then examine the mass-concentration relation, c(M), given by this model at present time over a huge range of halo masses, i.e. from Earth-mass microhalos up to galaxy clusters, and check its predictions against results from N-body cosmological simulations. Despite little knowledge of halo concentrations below 1e10 Msun in simulations, the model works remarkably well; indeed, it is compatible with all the available data down to Earth-mass microhalos within 1-sigma errors. Both the simulation results and the model show a clear flattening of the c(M) relation at lower masses that excludes the use of simplistic power-law c(M) models below the mass resolution of current simulations. This fact has important consequences e.g. for gamma-ray DM searches, as it implies more moderate enhancements of the DM annihilation flux due to DM substructure - the so-called substructure boost - than usually assumed. Recent works that derived or used substructure boosts >1000 for galaxy clusters and >200 for Milky Way-sized halos relied on such power-law extrapolations, and thus are clearly disfavored. We obtain much more moderate boosts, i.e. <50 for galaxy clusters and <20 for galaxies like our own. DM annihilations in dwarf galaxies are not significantly boosted by the presence of sub-substructure. These numbers have a critical impact on current DM searches as well as on future DM search strategies.

Speaker: Miguel Sanchez-Conde

Slides Sanchez_TeVPA13_masc_280813_short.pdf

17:30 The TeV Cosmic-Ray Anisotropy from Local Dark Matter Annihilation

Several experiments have reported regions in the TeV sky with an excess of cosmic rays. I will discuss the consistency of these cosmic-ray excesses with dark matter annihilations in a nearby subhalo. The dark matter explanation of the TeV cosmic-ray excess naturally explains both its spatial and spectral features. I will show that the dark matter annihilation rate needed to produce the excess is consistent with current measurements of antiprotons, positrons, and gamma-rays. Additionally, I will show the predicted signatures from the dark matter subhalo is several cosmic-ray channels, several of which are measurable by the next generation of experiments.

Speaker: Patrick Harding

Slides Harding_TeVPA_28August2013.pdf

17:50 Resolving small-scale Dark Matter structures using multi-source Indirect Detection

The extragalactic dark matter (DM) annihilation signal depends on the annihilation cross section, $\sigma v$, and the clumping or boost factor, $\langle \delta^{2}(z) \rangle $. The ``clumping factor--$\sigma v$'' degeneracy can however be broken by comparing DM annihilation signals from multiple sources. In particular, one can then constrain the minimum DM halo mass ($\rm M_{ min}$), which reflects the cutoff scale of the primordial power spectrum, by comparing individual DM sources to the diffuse DM annihilation signal. We demonstrate this with careful analytic treatments of the DM contribution to the Isotropic Gamma-Ray Background (IGRB) and comparisons to two recent hints of DM towards the Galactic Center (GC), namely, a $\sim130$ GeV DM annihilating dominantly in the $\chi\chi \to \gamma \gamma$ channel, and a $(10-30)$ GeV DM annihilating in $\chi\chi \to \tau\bar{\tau}$ or $\chi\chi \to b\bar{b}$ channels. We show that these DM candidates are conservatively unconstrained by Fermi measurements, but by taking into account astrophysical backgrounds, spectral and anisotropy information, as well as a more careful treatment of the isotropic Galactic component, can be used to probe values of $\rm M_{min}$ down to $10^{0}\,{\rm M_{\odot}}$ for the 130 GeV candidate, and $10^{-6}\,{\rm M_{\odot}}$ for some parameter space of the light DM candidates. Increasing the substructure content within a reasonable amount further improves these constraints.

Speaker: Kenny Chun Yu Ng

Slides Kenny_CY_NG_IGRB_TeVPA.pdf

18:10 Gamma-ray Probes of Dark Matter Halo Substructure

Cosmological simulations predict the presence of a significant population of substructure within dark matter halos. Being dark, these structures are very difficult to probe observationally. Gravitational lensing and baryon signatures give us some information, but cannot probe structures of smaller scales. Dark matter annihilation is a very sensitive probe of dark matter structure. I discuss methods for gamma-ray observations to probe substructure models.

Speaker: Sheldon Campbell

Slides Campbell_TeVPA2013.pdf

Thursday, 29 August

07:00 → 08:30 Breakfast

08:30 → 10:30 Plenary

08:30 Recent Results from the LHC

Speaker: David Berge (CERN)

Slides Berge_2013.pdf Berge_2013.pptx

09:00 Collider implications for dark matter

Speaker: Roni Harnik (Fermilab)

Slides Harnik_2013.pdf

09:30 What do we learn from the recent cosmic-ray positron measurements?

Speaker: Eli Waxman (Weizmann Institute of Science)

Slides Waxman_2013.pdf Waxman_2013.pptx

10:00 Astrophysical Probes of Dark Matter

Speaker: Stefano Profumo (UCSC)

Slides Profumo_2013.pdf Profumo_2013.pptx

10:30 → 11:00 Coffee Break

11:00 → 12:30 Plenary

11:00 Direct Detection of Dark Matter: Hints, Exclusions, and Future

Speaker: Enectali Figueroa (MIT)

Slides Figueroa_2013.pdf

11:30 Direct detection with noble liquids

Speaker: Dan McKinsey (Yale University)

Slides McKinsey_2013.pdf

12:00 Direct detection in China

Speaker: Kaixuan Ni (Shanghai Jiao Tong University)

Slides Ni_2013.pdf

12:30 → 14:00 Lunch Break

14:00 → 16:00 High-energy gamma rays

Conveners: Brenda Dingus (LANL), Justin Vandenbroucke (University of Wisconsin, Madison)

14:00 The Fermi bubbles: foreground subtraction and energy spectrum

The Fermi bubbles are a spectacular remnant of a past activity in or around the Galactic center. I will describe our analysis of the Fermi bubbles using 50 months of the Fermi-LAT data (pass7 reprocessed). One of the main challenges in the analysis is the separation of the Fermi bubbles from the other components of the Galactic diffuse emission. I will talk about two different methods to subtract the foreground emission. Results on the Fermi bubbles energy spectrum will be presented.

Speaker: Dmitry Malyshev

Slides Malyshev_2013.pdf

14:24 Search for Gamma-ray Spectral Lines with the Fermi Large Area Telescope

There is overwhelming evidence that non-baryonic dark matter constitutes ~27% of the energy density of the universe. Weakly Interacting Massive Particles are promising dark matter candidates that may produce monochromatic gamma rays via annihilation or decay. Such interactions would give a narrow spectral line in the Galactic diffuse gamma-ray energy spectrum. We have searched for spectral lines in the energy range 5--300 GeV using 3.7 years of data, reprocessed with updated instrument calibrations and an improved energy dispersion model compared to the previous Fermi-LAT Collaboration line searches. We searched in five regions selected to optimize sensitivity to different theoretically-motivated dark matter density distributions. We did not find any globally significant lines in our a priori search regions and present 95% confidence limits for WIMP annihilation cross sections and decay lifetimes. We will also discuss potential systematic effects in this search and why the significance of the line-like feature near 130 GeV is less than reported in other works.

Speaker: Andrea Albert

Slides Albert_2013.pdf

14:48 A GeV Gamma-Ray Spectral Feature in the Inner Galaxy

I will present evidence that the spectral feature in few-GeV diffuse gamma-rays previously identified in the Galactic Center (GC) extends to much higher Galactic latitudes, 5-20 degrees from the Galactic plane. I will discuss the spectrum and morphology of the signal and some systematic uncertainties in extraction of the spectrum, with their consequences for dark matter interpretations. Millisecond pulsars have been proposed as a possible source of the GC signal: I will comment on their potential to generate the extended inner Galaxy emission.

Speaker: Tracy Slatyer

Slides Slatyer_2013.pdf

15:12 Disentangling Hadronic and Leptonic Cascade Scenarios from the Very-high-energy Gamma-ray Emission of Hard-spectrum Blazars

The very-high-energy (VHE; > 100 GeV) gamma-ray spectra of extreme high-frequency peaked BL Lac objects and distant hard-spectrum blazars can be well explained either by gamma rays emitted at the source or by cascades induced by ultra-high-energy cosmic rays. The confirmation of the hadronic scenario provides strong evidence for the origin of ultra-high-energy cosmic rays. In this talk, we show that the two scenarios can be distinguished observationally by measuring the gamma-ray flux above >~ 1 TeV (depending on source redshift). Depending source redshift, if the often quoted redshift of KUV 00311-1938 (z = 0.61) is believed, the preliminary H.E.S.S. data favor cascades induced by ultra-high-energy cosmic rays. We also discuss the effect of magnetic fields surrounding the blazars in the hadronic cascade scenario.

Speaker: Hajime Takami

Slides Takami_2013.pdf

15:36 Neutron-Proton-Conversion Acceleration at Subphotospheres of Relativistic Outflows

We study a type of particle acceleration that operates via neutron-proton conversion (NPC) in in- elastic nuclear collisions. This mechanism can be expected for relativistic shocks at subphotospheres if relativistic outflows contain neutrons. Using a test-particle approximation, we numerically calcu- late the energy spectrum and the efficiency of accelerated particles, and show that a good energy fraction of the nucleons may be accelerated. The NPC acceleration may especially be relevant if the shock is radiation-mediated, and it would enhance the detectability of GeV-TeV neutrinos.

Speaker: Kazumi Kashiyama

Slides Kashiyama_2013.pdf

14:00 → 16:00 Particle physics

Conveners: Enectali Figueroa (MIT), Mariangela Lisanti (Princeton), Roni Harnik (Fermilab), Xiaojun Bi (IHEP, China)

14:00 Cosmic Axion Spin Precession Experiment (CASPEr)

We propose an experiment to search for QCD axion and axion-like-particle (ALP) dark matter. Nuclei that are interacting with the background axion dark matter acquire time-varying CP-odd nuclear moments such as an electric dipole moment. In analogy with nuclear magnetic resonance, these moments cause precession of nuclear spins in a material sample in the presence of a background electric field. This precession can be detected through high-precision magnetometry. With current techniques, this experiment has sensitivity to axion masses m_a <~ 10^(-9) eV, corresponding to theoretically well-motivated axion decay constants f_a >~ 10^16 GeV. With improved magnetometry, this experiment could ultimately cover the entire range of masses m_a <~ 10^(-6) eV, just beyond the region accessible to current axion searches.

Speaker: Surjeet Rajendran

Slides Rajendran_2013.pdf

14:24 Astrophysics-independent analysis of direct detection data

I will present an improved method to analyze and compare dark matter direct detection data independently of the WIMP halo density and velocity distribution. I will apply the method to various particle physics models in the few GeV WIMP mass region, which is of great interest due to several claims of possible signals and conflicting upper limits.

Speaker: Paolo Gondolo

Slides Gondolo_2013.pdf

14:48 Direct Detection of Self-interacting Dark Matter

Dark matter self-interactions have important implications for the distributions of dark matter in the Universe, from dwarf galaxies to galaxy clusters. In this talk, we present benchmark models that illustrate characteristic features of dark matter that is self-interacting through a new light mediator. These models have self-interactions large enough to change dark matter densities in the centers of galaxies in accord with observations, while remaining compatible with large-scale structure data and all astrophysical observations such as halo shapes and the Bullet Cluster. These observations favor a mediator mass in the 10−100 MeV range and large regions of this parameter space are accessible to direct detection experiments like LUX, SuperCDMS, and XENON1T.

Speaker: Hai-bo Yu

Slides Yu_2013.pdf

15:12 First results on neutrinoless double beta decay of Ge-76 by the GERDA experiment

Reported will be the result from the first phase of the GERmanium Detector Array (GERDA) experiment at the Gran Sasso Laboratory (INFN) on the search for neutrino-less double beta decay of the isotope 76Ge. The observation of this lepton number violating process, which is predicted by models beyond the Standard Model of particle physics, would imply that neutrinos are Majorana particles, ie. neutrinos are their own anti-particles. Provided that the exchange of light Majorana neutrinos is the leading mechanism of neutrino-less double beta decay, measuring or constraining the half-life sheds also light on the absolute neutrino mass scale. The data considered in the presented analysis was collected between November 2011 and May 2013 with a total exposure of 21.6 kg·yr. A blind analysis has been performed and all calibrations and event selection criteria had been finalized before the data were processed in the blinded 10 keV window around the Qββ-value of the 76Ge decay.

Speaker: Grzegorz Zuzel

15:36 The Effect of Gravitational Focusing on Annual Modulation

The scattering rate at dark-matter direct-detection experiments should modulate annually due to the Earth's orbit around the Sun. The rate is typically thought to be extremized around June 1, when the relative velocity of the Earth with respect to the dark-matter wind is maximal. We point out that gravitational focusing can alter this modulation phase. Unbound dark-matter particles are focused by the Sun's gravitational potential, affecting their phase-space density in the lab frame. Gravitational focusing can result in a significant overall shift in the annual-modulation phase, which is most relevant for dark matter with low scattering speeds. The induced phase shift for light O(10) GeV dark matter may also be significant, depending on the threshold energy of the experiment.

Speaker: Mariangela Lisanti

Slides Lisanti_2013.pdf

16:00 → 16:30 Coffee Break

16:30 → 18:30 High-energy gamma rays

Conveners: Brenda Dingus (LANL), Justin Vandenbroucke (University of Wisconsin, Madison)

16:30 Relativistic MHD Simulations of Ponyting Flux-Driven Jets

Relativistic, magnetized jets are observed to propagate to very large distances in many Active Galactic Nuclei (AGN). We use 3D relativistic MHD (RMHD) simulations to study the propagation of Ponyting flux-driven jets in AGN. These jets are assumed already being launched from the vicinity (~10^3 gravitational radii) of supermassive black holes and we follow the propagation of these jets to ~ parsec scales. We find that these current-carrying jets are collimated and mildly relativistic. When alpha, the ratio of toroidal-to-poloidal magnetic flux injection, is large the jet is subject to strong non-axisymmetric current-driven instabilities (CDI) which leads to substantial dissipation and reduced jet speed. However, even with the presence of instabilities, the jet is not disrupted and will continue to propagate to large distances. We present the detailed jet properties and show that far from the jet launching region, a substantial amount of magnetic energy is transformed into kinetic energy and thermal energy, producing a jet magnetization number sigma << 1. We note that jet collimation, CDIs, and the subsequent energy transitions are intrinsic features of current-carrying jets, and even in the toy model with a gas disk, we observe qualitatively similar jet behaviors.

Speaker: Xiaoyue Guan

Slides Guan_2013.pdf

16:54 The Gamma-ray Spectrum of PKS 1424+240, the Most Distant TeV Source

The very-high-energy (VHE) gamma-ray source PKS 1424+240, a blazar, has Lyman forest absorption in its UV spectrum out to a redshift of 0.6035, making it the most distant VHE gamma-ray source known. At a redshift at least this high, the most energetic gamma-rays detected in archival results from this blazar are expected to be strongly absorbed by interactions with the extragalactic background light. Correcting for this absorption results in a spectral shape not well described by a power law or log parabola. We expand upon this puzzling result with deeper VERITAS observations and contemporaneous Fermi Large Area Telescope and Swift XRT data. We show the particularly soft X-ray spectrum of the blazar, and explore possible mechanisms which might produce the unusual gamma-ray spectral shape.

Speaker: David Williams

Slides Williams_2013b.pdf

17:18 Multi-Messenger Tests of the IceCube Excess

The IceCube Collaboration has recently reported evidence for an extraterrestrial neutrino flux. The flux is consistent with an isotropic diffuse emission which favors an extragalactic origin. However, it is not yet possible to rule out a quasi-diffuse or sub-dominant emission from multiple high-latitude or extended Galactic sources. I discuss the implications of gamma-ray observations for various Galactic or extragalactic candidate sources of the IceCube excess. The contribution of Galactic sources can be tested via primary TeV-PeV gamma-rays from the decay of neutral pions produced in the same cosmic ray interactions. Hadronuclear interactions of cosmic rays in extragalactic sources can be tested by secondary GeV-TeV diffuse gamma-rays observed by Fermi.

Speaker: Markus Ahlers

Slides Ahlers_2013.pdf

17:42 Secondary photons and neutrinos from distant blazars and the intergalactic magnetic fields

Secondary photons and neutrinos produced in the interactions of cosmic ray protons and gamma rays emitted by distant Active Galactic Nuclei (AGN) with the photon background along the line of sight can reveal a wealth of new information about the intergalactic magnetic fields (IGMF), extragalactic background light (EBL), and the acceleration mechanisms of cosmic rays. The secondary photons may have already been observed by gamma-ray telescopes. With the inclusion of secondary photons the current upper limits on the extragalactic background light are significantly weakened and new limits are set for the intergalactic magnetic fields for a wide range of cosmic ray and gamma ray models. Recent results from IceCube may also hint at the first observation of secondary neutrinos. Ramifications for the cosmic backgrounds, magnetic fields, and AGN models will be discussed.

Speaker: Warren Essey

Slides Essey_2013.pdf

18:06 Long-term Optical Study of Extragalactic TeV sources

About forty (Mrk 421, Mrk 501, 1ES 1959+650 end others) northern TeV extragalactic sources have been discovered during last two decades. Most of them (2/3) we are monitoring in Abastumani Observatory from the beginning of 1997 using 125-cm and 70-cm meniscus telescopes. All observations (over 2500 nights) have been conducted with Apogee Ap6E and SBIG ST-6 CCD cameras in BVRI bands. The densest coverage is carried out during FERMI/LAT mission. The frames have been reduced using Daophot II and homogenous lightcurves have been constructed. The amplitudes of long-term variability are within 0.3-1.5 magnitudes. Few sources show Intraday variability within 0.05-0.15 magnitudes, while intra-night/micro-variability is below 0.05 magnitude. The results of multiwavelength campaigns with Whipple, VERITAS, HESS and MAGIC are also presented.

Speaker: Omar Kurtanidze

16:30 → 18:30 Particle physics

Conveners: Enectali Figueroa (MIT), Mariangela Lisanti (Princeton), Roni Harnik (Fermilab), Xiaojun Bi (IHEP, China)

16:30 Baryogenesis for WIMPs

We propose a robust, unified framework, in which the similar baryon and dark matter cosmic abundances both arise from the physics of weakly interacting massive particles (WIMPs), with the rough quantitative success of the so-called “WIMP miracle”. In particular the baryon asymmetry arises from the decay of a meta-stable WIMP after its thermal freezeout at or below the weak scale. A minimal model and its embedding in R-parity violating (RPV) natural SUSY are studied as examples. The new mechanism saves RPV SUSY from the potential crisis of washing out primordial baryon asymmetry. We also consider the embedding of this idea in RPV split SUSY. Phenomenological implications for the LHC and precision tests are discussed.

Speaker: Yanou Cui

Slides Cui_2013.pdf

16:54 Imprints of Non-thermal Wino dark matter on Small-Scale Structure

We study how "warm" the wino dark matter is when it is non-thermally produced by the decays of the gravitino in the early Universe. We clarify the energy distribution of the wino at the decay of the gravitino and the energy loss process after their production. By solving the Boltzmann equation, we show that a sizable fraction of the wino dark matter can be "warm" for the wino mass m_{\tilde w} \sim 100-500 GeV. The "warmness" of the wino dark matter leaves imprints on the matter power spectra and may provide further insights on the origin of dark matter via the future 21 cm line survey. Our calculations can be applied to other non-thermal wino production scenarios such as the wino dark matter produced by the decay of the moduli fields.

Speaker: Ayuki Kamada

Slides Kamada_2013.pdf

17:18 Kinetic Decoupling of Dark Matter in Effective Theories

I will discuss the kinetic decoupling of dark matter in the framework of effective theories where all interactions with the standard model are parametrized by contact interactions. New effects on the decoupling calculation within standard cosmology have been considered, including pion scattering after the QCD phase transition and loop-induced scattering off of leptons for primarily quark-interacting dark matter.

Speaker: William SHEPHERD

Slides Shepherd_2013.pdf

17:42 Implementing Simplified Models in the Search for Dark Matter

To understand and describe Dark Matter on a fundamental level, studies often focus on either a complete theory, such as the MSSM, or an effective field theory. Here we explore a middle ground: a Simplified Model, which specifies a generic UV complete interaction while ignoring structure not necessarily relevant to a calculation. How experiments compliment each other in the context of a UV complete theory and what is missed by the two extreme searches will be discussed. As a specific example, we look at fermionic Dark Matter and a scalar mediator interacting with quarks at the LHC and the direct detection experiments, XENON and COUPP.

Speaker: Anthony Difranzo

Slides DiFranzo_2013.pdf

18:06 Prospects and Blind Spots for Neutralino Dark Matter

Using a simplified model framework, we assess observational limits and discovery prospects for neutralino dark matter. Experimental constraints can be weakened or even nullified in regions of parameter space near 1) purity limits, where the dark matter is mostly bino, wino, or Higgsino, or 2) blind spots, where the relevant couplings of dark matter to the Z or Higgs bosons vanish identically. We analytically identify all blind spots relevant to spin-independent and spin-dependent scattering and show that they arise for diverse choices of relative signs among M1, M2, and μ. At present, XENON100 and IceCube still permit large swaths of viable parameter space, including the well-tempered neutralino. On the other hand, upcoming experiments should have sufficient reach to discover dark matter in much of the remaining parameter space.

Speaker: David Pinner

Slides Pinner_2013.pdf