Prof.
Jean-Marc Triscone
(University of Geneva)
14/12/2015, 09:07
Prof.
Thanu Padmanabhan
(ICAA Pune)
14/12/2015, 09:35
Talk
General Relativity revolutionized the way we we thought about gravity. After describing briefly the key successes of GR and their impact, I will discuss the major conceptual challenges it faces today. I will conclude by outlining the prospective future directions of development, which hold the promise for deepening our understanding of the nature of gravity further.
Camille Bonvin
(CERN)
14/12/2015, 10:10
Talk
The distribution of galaxies provides a powerful way to probe the properties of our universe. In order to exploit this observable properly it is necessary to understand what we are really measuring when we look at the large-scale structure. Since our universe is not completely homogeneous and isotropic, we only see a distorted picture of our sky. In this talk, I will discuss the various...
Nabila Aghanim
(Universite Paris Sud)
14/12/2015, 11:20
Talk
Over the last two decades cosmic microwave background (CMB) anisotropies have revolutionised our view of cosmology. Generations of experiments have successively uncovered the amplitude of the temperature fluctuations at large scales, the existence of acoustic peaks in both temperature and polarisation and the small scale damping. These observations have now established a minimal cosmological...
David Wands
(University of Portsmouth)
14/12/2015, 14:00
As high-redshift galaxy surveys probe ever larger volumes with increasing accuracy there is renewed interest, and some concern, about how the standard results derived within the standard Newtonian approach to large-scale structure should be understood within a relativistic framework. How and when do Newtonian results need to modified? Relativistic corrections arise in several ways. For...
Craig Hogan
(U. Chicago and Fermilab)
14/12/2015, 14:00
Talk
It is proposed that small amplitude, coherent rotational fluctuations arise from the emergence of nearly-classical non-rotating inertial frames from Planck scale quantum elements. An exact form is calculated for Planck scale correlations in the signal of a Sagnac type interferometer, where the light path encloses a large area of arbitrary shape, normalized using area quantization from...
Nukri Komin
(Wits University)
14/12/2015, 14:00
The Large Magellanic Cloud (LMC) is an irregular satellite galaxy of the Milky Way, which has been observed extensively at Very-High-Energy (VHE) gamma-rays with the H.E.S.S. telescopes, obtaining a deep exposure of 210 hours. In this talk we will present the results of this campaign.
Besides the already known PWN N 157B, these observations establish significant VHE gamma-ray emission from...
Dr
Timothée Delubac
(Ecole Polytechnique Fédérale de Lausanne)
14/12/2015, 14:00
Talk
The first detection of Baryon Acoustic Oscillations (BAO) in the correlation function of the galaxy density field by Eisenstein et al. (2005) and Cole et al. (2005) set a milestone in the era of precision cosmology, providing a new, independent method for the measurement of cosmological distances. The Baryon Oscillation Spectroscopic Survey (BOSS), one of the experiment of the third generation...
Dr
Eloisa Bentivegna
(Università degli Studi di Catania)
14/12/2015, 14:00
Talk
Building accurate, multi-scale models of the Universe is a complex but necessary task in the era of precision cosmology, when observational data demands a thorough understanding of all effects which are expected to contribute at the 1% level, among which the full role of General Relativity. This task has recently been tackled with a variety of approaches, which range from the study of toy...
Prof.
Diego Torres
(ICREA / Institute of Space Sciences)
14/12/2015, 14:00
Talk
Detected from radio to TeV gamma rays, the gamma-ray binary LS I + 61º303 is highly variable across all frequencies. Beside its variability due to the modulation of its emission due to the 26.496-day orbital period, the system also presents variability consistent with the so-called superorbital period, of 1667 days. We will present the latest data set of LSI +61º 303 taken with the Fermi Large...
Dr
Josefin Larsson
(KTH Royal Institute of Technology)
14/12/2015, 14:00
In recent years there has been growing evidence that emission from the photosphere of the jet contributes to the prompt emission in many GRBs. The photospheric emission is usually seen to coexist with a dominant non-thermal component. In this talk I will present an analysis of GRB 101219B, the second burst observed by Fermi GBM that is well described by pure blackbody emission. This burst also...
Dr
Thierry Stolarczyk
(IRFU/SAp,CEA Saclay, 91190 Gif-sur-Yvette (FR))
14/12/2015, 14:20
CTA is the next generation ground based gamma-ray observatory planned to start operations before the end of the decade. With tens of telescopes on sites in both hemispheres, it will allow probing the Milky Way with an unprecedented sensitivity and angular resolution, in the energy domain from a few tens of GeV to a few hundreds of TeV. I will review the CTA Galactic science program ranging...
Dr. Bikash Chandra PAUL
(University of North Bengal)
14/12/2015, 14:21
Talk
Emergent universe (EU) scenarios describe the evolution of a static Einstein universe in the infinite past whereby certain problems associated with the big-bang singularity can be circumvented. A flat universe composed of interacting fluids with a non-linear equation of state within the EU scenario leads to a viable cosmological model accommodating the presently observed accelerating era, as...
Björn Ahlgren
(KTH Royal Institute of Technology)
14/12/2015, 14:21
The prompt emission mechanism of gamma-ray bursts (GRBs) is still unknown. While GRB spectra are usually well fitted by the Band function, an empirically motivated, smoothly broken power law, this gives little understanding of the underlying radiation mechanism. In this talk I will present results from fitting a physical model to prompt GRB spectra observed by Fermi. The model simulates the...
Jaiyul Yoo
(University of Zurich)
14/12/2015, 14:21
We present the third-order analytic solution of the matter density fluctuation in the proper-time hypersurface of nonrelativistic matter flows by solving the nonlinear general relativistic equations. The proper-time hypersurface provides a coordinate system that a local observer can set up without knowledge beyond its neighborhood, along with physical connections to the local Newtonian...
Brett Bochner
(Hofstra University)
14/12/2015, 14:21
Talk
The pre-homogenized very early universe generically experiences Mixmaster-like behavior as it approaches the Big Bang, featuring a sequence of anisotropically expanding Kasner epochs. Beyond drawing general conclusions about the transport of mass-energy in such environments, it would be helpful to obtain as much information as possible about the detailed propagation of energy in rapidly and...
Dr
Ricardo Génova Santos
(Instituto de Astrofísica de Canarias)
14/12/2015, 14:25
The QUIJOTE (Q-U-I JOint TEnerife) experiment is a new polarimeter working in the frequency range 10-40 GHz, and designed to characterize the primordial B-mode anisotropy of the CMB polarization down to a sensitivity in the tensor-to-scalar ratio of r~0.05, and to measure the level of the polarization of low-frequency Galactic foregrounds (the synchrotron and the anomalous dust emissions). The...
Guillaume DUBUS
(IPAG CNRS/Université Grenoble Alpes)
14/12/2015, 14:26
Talk
The presence of a relativistic pulsar wind has been established in several X-ray binaries. The interaction of the pulsar wind with the stellar companion, stellar wind, or accretion disk can lead to peculiar signatures, most prominently the emission of high-energy gamma-rays. I will describe our efforts to model this interaction in order to translate gamma-ray observations into a better...
Justyna Średzińska
(Nicolaus Copernicus Astronomical Center PAS)
14/12/2015, 14:27
Talk
The discovery of the accelerated expansion of the Universe lead to the concept of dark energy. This is one of the most interesting topic in modern relativistic astrophysics. Precise measurement of this effect is a key to understand the nature of this medium, and we need good probes to do that. Quasars appears as an ideal candidate for this purpose as these objects are highly luminous and...
Dragan Hajdukovic
(Institute of Physics, Astrophysics and Cosmology)
14/12/2015, 14:42
Talk
It was recently suggested that what we call dark matter and dark energy, can be explained as the local and global effects of the gravitational polarization of the quantum vacuum by the immersed Standard Model matter. This result appears as the consequence of the working hypothesis that by their nature quantum vacuum fluctuations are virtual gravitational dipoles. Here, we argue that, as a...
Marco Bruni
(University of Portsmouth)
14/12/2015, 14:42
Talk
I introduce new exact solutions of the Szekeres-Szafron type describing voids on a Friedmann-Roberson-Walker background with w=constant equation of state. At least in the linear regime the inhomogeneities can be thought of as large scale perturbations of the background. Using these exact solutions the averaged quantities of the Buchert scheme can be calculated exactly. I show that in general...
Elena Moretti
(MPI Munich)
14/12/2015, 14:42
The era of the Band function paradigm is ending, due in large part to the high-quality data provided by the Fermi Gamma-ray Space Telescope. Practically all bright GRBs detected by Fermi-LAT and GBM data show deviations from a pure Band function, most often due to extra spectral features being present. Understanding the physics of these components is necessary to reveal the acceleration and...
Jens Chluba
(Institute of Astronomy)
14/12/2015, 14:45
CMB spectral distortions caused by energy release in the early Universe create broad distortions that are usually described as superposition of mu-, y- and r-type distortions. These signals will allow us to gain new insights into the pre-recombination Universe, telling us about early-universe and particle physics. There is, however, another way to create distortions: by *photon injection*. One...
Dr
Shiu Hang (Herman) Lee
(ISAS/JAXA)
14/12/2015, 14:45
Recent observations by the Large Area Telescope (LAT) onboard the Fermi satellite have revealed bright gamma-ray emission from middle-aged supernova remnants (SNRs) inside our Galaxy. These remnants which also possess bright non-thermal radio shells are often found to be interacting directly with surrounding gas clouds. We explore the non-thermal emission mechanism at these dynamically evolved...
Pere Munar-Adrover
(INAF-IAPS)
14/12/2015, 14:52
Talk
MWC 656 is a Be star with a black hole (BH) companion, being the first and unique Be/BH binary system found. The detected X-ray counterpart implies that MWC 656 is, as well, the first Be/BH X-ray binary found. We carried out a search in archival AGILE data and found ten gamma-ray flares compatible with the position of the binary system, although no periodicity in the gamma-ray activity has...
Lorenzo Amati
(INAF - IASF Bologna)
14/12/2015, 14:53
Talk
Given their huge isotropic-equivalent radiated energies, up to more than 10$^{54}$ erg released in a few tens of seconds,
and their redshift distribution extending up to more than z = 9, Gamma-Ray Bursts (GRB) are in principle a powerful tool for
measuring the geometry and expansion rate of the Universe. In the recent years, several attempts have been made to
exploit the correlation between...
Jonathan Braden
(University College London)
14/12/2015, 15:03
Talk
First-order phase transitions proceed through the nucleation and subsequent collision of bubbles. In false vacuum eternal inflation, such collision events are ubiquitous and provide a possible avenue to observationally test the multiverse. They also play an important role in early high temperature phase transitions.
I will present results for the full three-dimensional nonlinear dynamics...
Maria Dainotti
(Stanford University)
14/12/2015, 15:03
An analysis of 176 GRBs with known redshift observed by Swift which present afterglow plateau revealed a new tri-parameter correlation (Lpeak,Lx,T*a) where Lpeak is the peak luminosity in the prompt emission, Lx is the luminosity at the end of the plateau emission and T*a is the rest frame time at the end of the plateau emission. We have already proven the intrinsic nature of the Lx- T*a...
Dr
Chandrachur Chakraborty
(Tata Institute of Fundamental Research , Mumbai , INDIA)
14/12/2015, 15:03
Talk
The exact Lense-Thirring precession frequencies for Kerr, Kerr–Taub–NUT,Taub–NUT, Plebanski-Demianski spacetimes are explicitly derived. Remarkably, in the case of the zero angular momentum Taub–NUT spacetime, the frame-dragging effect is shown not to vanish, when considered for spinning test gyroscopes. In the case of the interior of the rotating neutron stars, the exact frame-dragging rate...
Mario Ballardini
(University of Bologna)
14/12/2015, 15:03
The predictions of the simplest
inflationary models, such as a flat Universe and Gaussian adiabatic
perturbations with a red tilt, provide a remarkable good fit to the most
recent measurements of CMB temperature and
polarization anisotropies. Nevertheless, deviations from a simple
power-law spectrum provide a better fit to Planck temperature anisotropies
data, in particular on the...
Dr
Juan Francisco Macias-Perez
(LPSC)
14/12/2015, 15:05
Clusters of galaxies are the largest bound structures in the Universe. Thus, they are observables of choice for cosmology both in terms of their aboundance and of their distribution on the sky. Clusters of galaxies can be observed at different wavelengths via their X-ray and radio emission as well as from the optical emission of their galaxies. In addition, they can be studied via the thermal...
Friedrich Thielemann
(University of Basel)
14/12/2015, 15:18
Talk
The origin of the heavy elements made by the rapid neutron-capture process (”r-process”) is not fully understood, yet. Different sources have been proposed, e.g., core-collapse supernovae as well as neutron star mergers.
- We discuss the production of r-process elements in three of these suggested sites:
1.the neutrino wind in core collapse supernovae, 2. jet ejecta from...
Mr
Phillip Helbig
(*)
14/12/2015, 15:19
Talk
The magnitude-distance relation for type Ia supernovae is one of the key pieces of evidence supporting the cosmological "concordance model". The resulting constraints on the cosmological parameters are often derived under the idealized assumption that the universe is perfectly homogeneous (at least as far as light propagation is concerned). However, we know that the universe is not...
Lavinia Heisenberg
(ETHZ - ETH Zurich)
14/12/2015, 15:24
Talk
In order to regularize the energy of point-like charged particles, Born and Infeld introduced a modification of the Maxwell lagrangian that naturally imposes an upper bound on electromagnetic fields. This approach was later taken by Deser and Gibbons to propose an analogous modification for gravity. I will review these ideas and discuss a scenario where inflation could be supported by a set of...
Dr
Nicolas Produit
(Universite de Geneve (CH))
14/12/2015, 15:24
The POLAR detector will be launched together with the Tiangong 2
Chinese space station in the Summer of 2016 from Jiuquan Launch center.
POLAR is a GRB polarimeter that will be able to measure GRB polarization
degree with 10% precision for 10 GRB per year. POLAR detector has been build by a
Chinese-Swiss-Polish collaboration.
POLAR flight spare model has passed all
qualification tests...
Mariusz Dabrowski
(University of Szczecin)
14/12/2015, 15:24
Talk
I will discuss the benefits of the conformally flat inhomogeneous pressure models of the universe. Then, I will present the results of checking these models against supernovae data for off-centers observers and against other data (BAO, CMB) for the centrally-placed observers. I will also comment on the possible advantage of these models in view of the recently given Green and Wald conditions...
Francesco Montanari
(Universite de Geneve (CH))
14/12/2015, 15:24
We investigate how well the lensing potential can be measured tomographically with future galaxy surveys using their number counts. Such a measurement is a consistency test of the standard ΛCDM framework.
Based on galaxy angular-redshift power spectra, our analysis suggests that the survey can measure the amplitude of the lensing potential at the same level of precision as other standard ΛCDM...
Matteo Balbo
(Université de Genève)
14/12/2015, 15:25
The Fermi Large Area Telescope (LAT) observed for the first time ever two consecutive $\eta$Carinae periastron passages. The large field of view of the instrument, its performing sensitivity and homogeneous exposition offers a continuous observation above 100 MeV of the $\eta$Carinae region on the last 7 years. $\eta$Carinae is a binary system hosted in the Carina nebula. Its luminous blue...
Prof.
Jai-chan Hwang
(Kyunpook National Univ.)
14/12/2015, 16:15
We present the leading order nonlinear density and velocity power spectra
including the vector- and tensor-type perturbation simultaneously excited
by the scalar-type perturbation in nonlinear order.
Concerning density and velocity perturbations of the pressureless matter
in perturbation regime well inside of matter-dominated epoch, we show that
pure Einstein’s gravity contributions...
Ms
Isabel Oldengott
(Universität Bielefeld)
14/12/2015, 16:15
We study the impact of dark matter decay on cosmic reionization. We derive new constraints on the dark matter decay rate by using the newest CMB observations, assuming two different parametrizations of standard reionization.
Andrey Shkerin
(EPFL)
14/12/2015, 16:15
Talk
We study Coleman – De Luccia tunneling of the Standard Model Higgs field during
inflation in the case when the electroweak vacuum is metastable. We verify that the
tunneling rate is exponentially suppressed. The main contribution to the suppression
is the same as in flat space-time. We analytically estimate the corrections due to the
expansion of the universe and an effective mass term in...
Dr
Takayuki Saito
(Kyoto University)
14/12/2015, 16:15
Although more than 150 gamma-ray pulsars are known in GeV band, their spectra roll off above 10 GeV and only two pulsars are detected at about 50 GeV, namely Crab and Vela. There is also a large difference between Crab and Vela. Crab spectrum is extending above 1 TeV, while Vela has a very soft spectrum, becoming almost undetectable at 100 GeV.
In order to further understand the emission...
Patrizia Romano
(INAF)
14/12/2015, 16:15
Talk
We present the results of the Swift Supergiant Fast X-ray Transients project,
which has been exploiting *Swift*'s capabilities in a systematic study of SFXTs and classical
supergiant X-ray binaries (SGXBs) since 2007.
The unique combination of sensitivity and scheduling flexibility of *Swift*/XRT
allowed us to perform an efficient long-term monitoring of 16 including both SFXTs and...
Clare Burrage
(University of Nottingham)
14/12/2015, 16:15
Talk
I will discuss the prospect that the first evidence for dark energy may be found through meter scale, laboratory based, atom interferometry experiments. I will discuss how, in order to be compatible with fifth force constraints, dark energy scalar fields must have a screening mechanism which hides their effects from us within the solar system. Focusing in particular on one such screening...
Rob Preece
(University of Alabama in Huntsville)
14/12/2015, 16:15
Although they are not standard candles, gamma-ray bursts (GRBs) are quite definitely cosmological objects, with some of the highest redshifts observed. The problem remains how to use GRB observables to construct a usable Hubble diagram. Several correlations between observables and the energetics have been noted, e.g. Amati et al. (2002) and Yonetoku et al. (2004), but it is not clear whether...
Dr
Daniel G. Figueroa
(CERN)
14/12/2015, 16:35
Talk
I will present the cosmological implications of the decay of the Standard Model Higgs after Inflation, when assuming a post-inflationary/pre-BBN expansion history driven by a stiff source with equation of state w > 1/3. In particular, I will discuss first the realisation of a successful 'reheating' mechanism, and secondly, the production of a large background of gravitational waves by the...
Julian Adamek
(Université de Genève)
14/12/2015, 16:35
The Newtonian approximation which is usually invoked in N-body simulations of cosmic large scale structure relies on the assumptions that gravitational fields are weak and that they are only sourced by nonrelativistic matter. The latter constitutes an implicit assumption about the nature of the "dark" components of the Universe (dark matter and dark energy), thereby precluding a serious...
Ms
Daniela Saadeh
(University College London)
14/12/2015, 16:35
Large scales in the Cosmic Microwave Background (CMB) may break statistical isotropy. Bianchi models are often invoked as a possible explanation for these low-\ell features: they provide an anisotropic underlying pattern over which the usual stochastic fluctuations are superimposed. However, the Bianchi models generally employed in the analysis of CMB data — despite mimicking the anomalies in...
Mikhail Katanaev
(Steklov Mathematical Institute, Moscow)
14/12/2015, 16:35
Talk
We give a simple example of space-time metric, illustrating that homogeneity and isotropy of space slices at all moments of time is not obligatory lifted to a full system of six Killing vector fields in space-time, thus it cannot be interpreted as a symmetry of a four dimensional metric. The metric depends on two arbitrary and independent functions of time. One of these functions is the usual...
Lorenzo Amati
(INAF - IASF Bologna)
14/12/2015, 16:35
The Transient High Energy Sky and Early Universe Surveyor (THESEUS) is a mission concept developed by a large international collaboration aimed at exploiting Gamma-Ray Bursts for investigating the early Universe. The main scientific objectives of THESEUS include: investigating the star formation rate and metallicity evolution of the ISM and IGM up to redshift 10, detecting the first generation...
Chandreyee Maitra
(CEA Saclay)
14/12/2015, 16:35
PSR J0855-4644 is a nearby, fast spinning, and energetic radio pulsar spatially coincident with the rim of the supernova remnant RX J0852.0-4622 (aka Vela Jr). XMM Newton observations of the pulsar region have shown an arcmin scale extended emission, the pulsar wind nebula (PWN), around the X-ray counterpart of the pulsar. Here, we present results from the small scale structure of the nebula...
Ignacy Leonard Sawicki
(University of Geneva)
14/12/2015, 16:40
Talk
I will discuss how considerations of causality put constraints on modifications of gravity where the perturbations in new degrees of freedom propagate on an acoustic metric different from the space time metric. More to come.
Alexander Lutovinov
(Space Research Institute)
14/12/2015, 16:40
Talk
Review of the most prominent results obtained with the INTEGRAL observatory for high-mass X-ray binary systems (HMXBs) is presented. Hard X-ray observations by INTEGRAL have broadened significantly our knowledge about X-ray binaries in the Milky Way. During dozen years the observatory discovered new types and populations of binary systems, like supergiant fast x-ray transients, heavily...
Dr
J. Michael Burgess
(KTH Royal Institute of Technology)
14/12/2015, 16:55
The prompt emission of the long, smooth, and single-pulsed gamma-ray
burst, GRB 141028A, is analyzed under the guise of an
external shock model. First, we fit the gamma-ray spectrum with a
two-component photon model, namely synchrotron+blackbody, and then
fit the recovered evolution of the synchrotron vFv peak to an
analytic model derived considering the emission of a...
Geraint Pratten
(University of Sussex)
14/12/2015, 16:55
Talk
In this talk I will review recent results regarding covariant, gauge-invariant perturbations to the scalar-tensor Schwarzschild black hole in the 1+1+2 formalism. I will discuss how we can introduce a set of master functions based on the Weyl tensor in order to cleanly decouple the evolution of tensor modes from the scalar modes. Relations to 2+2 and Newman-Penrose formalism will be briefly discussed.
Mr
Giovanni Cabass
(Physics Department and INFN, “La Sapienza” University of Rome)
14/12/2015, 16:55
Gravitational waves can be produced by a wide range of astrophysical phenomena, such as inspiral and merging of neutron stars and black holes, supernova of massive stars, accreting neutron stars, etc. This talk is focused, instead, on a stochastic background of gravitational waves (GWs) of cosmological origin, like the one predicted by inflation.
I start by considering a power law...
Marco Bruni
(University of Portsmouth)
14/12/2015, 16:55
General-relativistic cosmological models where vacuum interacts with cold dark matter (iV-CDM models) maybe a good alternative to the standard LCDM scenario. The post-Friedmann approximation generalises to cosmology post-Newtonian methods and we have used it to extract frame-dragging, a pure GR effect, from standard N-body simulations in LCDM and in f(R) models. After briefly summarising the...
Francesco Cefalà
(University of Basel)
14/12/2015, 16:55
Talk
I will first give a short overview of preheating after hilltop inflation. In the main part of the talk I will discuss how the dynamics can change
when the inflaton couples to another scalar field, e.g. a right-handed sneutrino, which provides a mechanism for generating the correct initial conditions for inflation and also a decay channel for the inflaton that allows for non-thermal...
Massimiliano Rinaldi
(University of Trento)
14/12/2015, 17:05
Talk
We study the Einstein Yang-Mills Higgs equations in the SO(3) representation on a isotropic and homogeneous flat Universe, in the presence of radiation and matter fluids. We map the equations of motion into an autonomous dynamical system of first-order differential equations and we find the equilibrium points. We show that there is only one stable fixed point that corresponds to an accelerated...
Wessel Valkenburg
(Leiden University)
14/12/2015, 17:15
Talk
A repetition of the same high-resolution and large-volume observation, after ten or more years, gives access to the fourth dimension in observational cosmology, perpendicular to the light-cone. I discuss how various toy models can be distinguished by decomposing the long-time-difference maps into multipole vectors. A next-generation GAIA-like satellite with ten times GAIA's resolution, should...
Laura Salvati
(University of Rome, Sapienza)
14/12/2015, 17:15
We show how to derive new constraints on the neutron lifetime based on cosmological observations. Under the assumption of standard Big Bang Nucleosynthesis, the abundance of light elements, in particular Helium, is strongly dependent on the neutron lifetime. From CMB anisotropies it is possible to constrain primordial abundances of light elements, inferring the value of the neutron lifetime....
Mr
Simone Giacche`
(Max-Planck Institute for Nuclear Physics)
14/12/2015, 17:15
The Pulsar Wind Nebulae (PWNe) PSR B1259-63 has been
observed to emit periodic GeV flares, whose power can be
comparable to the total pulsar spin-down luminosity.
Because of the short timescale involved,
these photons are likely to be
produced via inverse Compton scattering of stellar photons or
Synchrotron radiation by a population of very energetic electrons
(from GeV to TeV energies)...
Vitalii Sliusar
(Astronomical Observatory of Taras Shevchenko National University of Kyiv, Ukraine)
14/12/2015, 17:15
We propose a numerical approach to study the inhomogeneity growth in the Universe filled with a pressureless matter. The hydrodynamical equations for perturbations of the isotropic uniform cosmological background (non-relativistic stage) in the comoving frame are treated taking into account all nonlinear terms. The periodic boundary conditions are imposed. The problem is reduced to ordinary...
Stefano Orani
(Basel University)
14/12/2015, 17:15
Talk
During hilltop inflation, the inflaton rolls away from the maximum of its potential and towards the minimum where the universe reheats. The first stage of reheating, preheating, is non-perturbative and, in this model, localized oscillating bubbles of the inflaton field, called oscillons, are formed. Furthermore, when other fields are present, they can be produced via a parametric resonance...
Ms
Pragati Pradhan
(St. Joseph's College, Darjeeling, India & North Bengal University, Siliguri, India)
14/12/2015, 17:25
Talk
We present a broadband spectral analysis of classical HMXBs (supergiant and
Be/X-ray binaries) and Supergiant Fast X-ray Transients (SFXTs) using data
from XIS and PIN instruments onboard Suzaku. After fitting the X-ray spectra
of 36 sources with a single model: a powerlaw and a high energy cutoff (where
required), we studied the correlation between various spectral parameters.
We present...
Yves Dirian
(University of Geneva)
14/12/2015, 17:29
Talk
We study the cosmological predictions of two recently proposed non-local modifications of General Relativity. Both models have the same number of parameters as $\Lambda$CDM, with a mass parameter $m$ replacing the cosmological constant. We implement the cosmological perturbations of the non-local models into a modification of the CLASS Boltzmann code, and we make a full comparison to CMB,...
Giuseppe Fanizza
(Università degli Studi di Bari "Aldo Moro")
14/12/2015, 17:35
Talk
The remarkable properties of the recently proposed geodesic light-cone (GLC) gauge allow to get some new interesting results to face the problem of inhomogeneities and their backreaction. Indeed, GLC simply consists of gauge fixing the metric tensor on the past light-cone of the observer. Thanks to this choice, several interesting physical observables, related to photons, can be evaluated...
Sergey Sibiryakov
(CERN & EPFL & INR RAS)
14/12/2015, 17:35
I will present a new perturbative approach to the description of cosmological structures in the mildly non-linear regime relevant at the distance scales from 10 to 100 Mpc. In this framework equal-time correlation functions of cosmological perturbations are calculated using an ensemble with time-dependent statistical weight. The scheme is free from unphysical infrared divergencies plaguing the...
Mr
Jacopo Fumagalli
(Nikhef)
14/12/2015, 17:35
The idea of introducing a non minimal coupling between the Higgs boson and the gravity sector gives successful predictions for inflation without needing new particles beyond the ones we know. Quantum mechanically the model is only consistent until the unitarity cutoff.
Possible UV completions beyond this cutoff could change its predictions. If this is the case it means that we would lose...
Ms
Nazma Islam
(Indian Institute of Science, Raman Research Institute, Bangalore, India)
14/12/2015, 17:45
Talk
GX 301-2, a bright high-mass X-ray binary with an orbital period of 41.5 days, exhibits stable periodic orbital intensity modulations with a strong pre-periastron X-ray flare. Several models have been proposed to explain the accretion at different orbital phases, invoking accretion via stellar wind, equatorial disc, and accretion stream from the companion star. We present results from...
Mr
Erick Jonathan Almaraz Aviña
(Instituto de Física / UNAM)
14/12/2015, 17:53
Poster
The physical explanation of the dark energy as the responsible agent of the currently accelerated expansion of the Universe remains as one of the most challenging questions of the modern physcis. Besides the standard scenario (in which it is caused by a cosmological constant) there are other proposals which range from the introduction of new more or less exotic components, to modifications to...
14/12/2015, 17:55
Dr
Krzysztof Nalewajko
(Stanford University)
14/12/2015, 17:55
We will present the results of kinetic particle-in-cell numerical simulations of relativistic harmonic magnetic equilibria, so called "ABC fields". These equilibria have been recently shown by relativistic magnetofluid simulations to be generally unstable. An ideal plasma instability leads to the formation of dynamical current layers where magnetic energy is dissipated via reconnection and...
Mrs
Roberta Del Vecchio
(Astronomical Observatory of the Jagiellonian University)
14/12/2015, 17:55
Poster
In this work we study the distribution of temporal power-law decay indices, $\alpha$, in the Gamma Ray Burst (GRB) afterglow
phase,
fitted for a sample of $164$ long GRBs with known redshifts using a power-law form. These indices are compared to the values of characteristic afterglow
luminosity,
$L_a$, the time, $T_a^*$, and the analogous decay index, $\alpha_W$, derived with global...
Ms
Mariana Jaber
(Universidad Nacional Autónoma de México)
14/12/2015, 17:56
Poster
For this work a parametrization for the Dark Energy (DE) equation of state is proposed and tested.
We derive constraints on our state equation parameters from the baryon acoustic oscillation (BAO) measurements. In particular we take advantage of high precision BAO measurements from galaxy clustering and the Lymann-$\alpha$ forest in the SDSS-III Baryon Oscillation Spectroscopic Survey...
Graziella Pizzichini
(INAF)
14/12/2015, 17:58
Poster
I shall compare the observed properties of high redshift long Gamma-Ray Bursts with those at lower redshifts
attaallah almasi
(vu university of amsterdam)
14/12/2015, 17:59
Poster
The search for non-Newtonian forces has been pursued following many different paths. Recently it was suggested that hypothetical chameleon interactions, which might explain the mechanisms behind dark energy, could be detected in a high-precision force measurement. In such an experiment, interactions between parallel plates kept at constant separation could be measured as a function of the...
Dr
Giovanni De Cesare
(IASF-Bologna),
Giulia Stratta
(Urbino University), Dr
Giuseppe Greco
(Urbino University), Dr
Marica Branchesi
(Urbino University)
14/12/2015, 18:01
Poster
Short Gamma Ray Bursts (SGRBs) are among the best source candidates of simultaneous electromagnetic radiation and gravitational waves (GWs) in the frequency range covered by the imminent second generation laser interferometer detectors Advanced LIGO and Advanced Virgo.
SGRB afterglow properties in the electromagnetic spectrum (e.g. photon flux intensity, variability time scale) can be very...
Jacob Moldenhauer
(University of Dallas)
14/12/2015, 18:02
Poster
It is not only important to constrain the parameters of cosmological models with the most recent and precise observations, but it is also crucial to understand the physical consequences of those parameters for the different, but complimentary observations involved. CosmoEJS is an interactive Java package of simulations that allow the user to explore the ramifications of choosing various...
Chandreyee Maitra
(CEA Saclay)
14/12/2015, 18:05
Talk
We present detailed broadband timing and spectral analysis of the persistent, low luminosity and slowly spinning pulsar 'X-per' using a Suzaku observation of the source. The spectrum is unusually hard with pulsations detected up to 70 keV. The spectrum also hosts several interesting features like evidence of a cyclotron line at 30 keV, and presence of a soft-excess below 2 keV. Considering...
Mr
Hanwool Koo
(Seoul National University)
14/12/2015, 18:05
Poster
By analyzing the spin alignment of isolated galaxy pairs from SDSS DR10 and in N-body simulation data for the coupled dark energy (cDE) model, we constrain the strength of dark sector interaction of cDE model. We perform Kolmogorov-Smirnov 2-sample tests to 6 different cases, one is the spin alignments from SDSS DR10 and in N-body simulation data for LCDM model, others are the spin alignments...
Dragan Hajdukovic
(Institute of Physics, Astrophysics and Cosmology (ME))
14/12/2015, 18:08
Poster
Our study is based on the working hypothesis that by their nature quantum vacuum fluctuations are virtual gravitational dipoles. This hypothesis is the simplest solution to the cosmological constant problem and opens the possibility to consider the known Standard Model matter (i.e. matter made from quarks and leptons interacting through the exchange of gauge bosons) as the only content of the...
Anna Paula Bacalhau
(Centro Brasileiro de Pesquisas Físicas)
14/12/2015, 18:12
Poster
In this work we investigate the features of the primordial power spectrum when it arises from a contracting phase in the context of a bouncing Universe.
We consider a toy model in which the Universe is dominated by a scalar field with an exponential potential, further on referred as the quintessence component. This choice is motivated by known results in the literature showing that such...
Christian Byrnes
(University of Sussex (GB))
14/12/2015, 18:15
Talk
It is both remarkable, and disappointing, that only two parameters describing the primordial perturbations can explain the statistical properties of millions of CMB temperature perturbations. However, the persistence of several large-scale cosmological anomalies in WMAP and Planck satellite data may provide a clue to new physics. I will discuss how inflationary models can explain the observed...
Jérôme Pétri
(Université de Strasbourg)
14/12/2015, 18:15
Poster
The magnetic field topology in the surrounding of neutron stars is one of the key questions in pulsar magnetospheric physics. A very extensive literature exists about the assumption of a dipolar magnetic field but very little progress has been made in attempts to include multipolar components in a self-consistent way. In this talk, we study the effect of multipolar electromagnetic fields...
Alicia Simon-Petit
(Applied Mathematics Laboratory, ENSTA ParisTech, Université Paris-Saclay)
14/12/2015, 18:15
Poster
How effective barotropic matter can emerge from the interaction of cosmological fluids in an isotropic and homogeneous cosmological model ?
The dynamics of homogeneous and isotropic Friedmann-Lemaître-Robertson-Walker universes is a natural special case of generalized Lotka-Volterra systems where each of the universe's fluid components can be seen as a competitive species in a predator-prey...
Mr
Junsup Shim
(Seoul National University)
14/12/2015, 18:15
Poster
We present how an anisotropic pattern of the cosmic web, which is vividly reflected in the filamentary structure of supercluster, changes if 1)the nature of dark energy differs from the cosmological constant or 2)the gravitational law deviates from the general theory of relativity with/without massive neutrinos. 1)The coupled dark energy (cDE) model where the coupling between dark energy and...
Ms
Nazma Islam
(Indian Institute of Science, Raman Research Institute, India)
14/12/2015, 18:20
Poster
In the absence of detectable pulsations in the eclipsing High Mass X-ray binary 4U 1700–37, the orbital period decay is necessarily determined from the eclipse timing measurements. We have used the earlier reported mid-eclipse time measurements of 4U 1700–37 together with new measurements from long term light curves obtained with the all sky monitors RXTE–ASM, Swift–BAT and MAXI–GSC, as well...
Ileyk EL MELLAH
(Paris 7 Diderot - APC laboratory)
14/12/2015, 18:24
Poster
Compact objects in high mass X-ray binaries (HMXB), where the companion star underfills its Roche lobe, have been spotted as X-ray emitters, probably due to the presence of a surrounding disc, along with their low mass counterparts (LMXB). However, if the disc formation is well understood in LMXB where matter is poured through the first Lagrangian point, things get messier in HMXB,...
David LANGLOIS
(CNRS)
15/12/2015, 09:00
Talk
I will present an effective description of dark energy/modified gravity models involving a single scalar field. It is based on a 3+1 splitting of space-time with respect to uniform scalar field hypersurfaces. The advantage of this approach is that it can describe in the same language a vast number of existing models, including quintessence, F(R) gravity, Horndeski theories, as well as...
Prof.
Laura Baudis
(University of Zurich)
15/12/2015, 09:35
Talk
A major challenge of modern physics is to decipher the nature of dark matter. Astrophysical observations provide ample evidence for the existence of an invisible and dominant mass component in the observable universe, from the scales of galaxies up to the largest cosmological scales. The dark matter could be made of new, yet undiscovered elementary particles, with allowed masses and...
Prof.
Hiranya Peiris
(University College London)
15/12/2015, 10:10
Talk
Surveys of the cosmic microwave background and large galaxy surveys of the next decade carry immense promise for measurements of new physics beyond the Standard Models of cosmology and particle physics. However, these observations are complicated by multiple sources of systematics, either intrinsic, observational, or instrumental, which must be carefully controlled in order to make reliable...
Prof.
Anna Watts
(University of Amsterdam)
15/12/2015, 11:20
Talk
With an average density higher than the nuclear density, neutron stars provide a unique test bed for nuclear physics, quantum chromodynamics, and nuclear superfluidity. Determination of the fundamental interactions that govern matter under such extreme conditions is one of the major unsolved problems of modern physics and - since it is impossible to replicate these conditions on Earth - a...
Prof.
Fulvio Ricci
(University of Rome La Sapienza and INFN Sez. Roma)
15/12/2015, 11:55
Talk
The european detector Advanced Virgo is ending the installation phase and the plan is to run during 2016 joining the LIGO detectors installed in USA. Its improved sensitivity will increase the detection probability of GW events.
In this talk we summarize the scientific outcome of the old network of advanced detectors in the past configuration. Then, we emphasize the potentialities of the new...
Prof.
Philipp Kronberg
(University of Toronto)
15/12/2015, 14:00
A non-negligible fraction of a Supermassive Black Hole's (SMBH) rest mass energy gets transported into extragalactic space - by remarkable processes in jets which are not completely
understood. The bulk of the energy flow from the SMBH (e.g. $10^7$ M$_\odot$) appears to be
electromagnetic, rather than via a particle beam flux. Also, remarkably, these jets contain current flows that remain...
Martina Gerbino
(University of Rome 'Sapienza')
15/12/2015, 14:00
The absolute scale of neutrino masses is one of the main open issues both in cosmology and particle physics. Current experimental strategies involve i) measurements exploiting kinematics effects in beta decay, ii) searches for neutrinoless double beta decay ('0n2b'), and iii) cosmological observations. The three approaches are complementary, each of them presenting its own advantages and...
Aurélien Sourie
(LUTH - Observatoire de Paris)
15/12/2015, 14:00
We present a realistic numerical model for rotating superfluid neutron stars in a full general relativistic framework. Following the work initiated by Prix, Novak & Comer [1], we compute stationary axisymmetric configurations of neutron stars composed of two fluids, namely superfluid neutrons and charged particles (protons and electrons), which are free to rotate around a common axis with...
Matteo Martinelli
(ITP, Heidelberg)
15/12/2015, 14:00
Talk
The latest cosmic microwave background data obtained by ESA Planck satellite allow us to test the evolution and content of the Universe in great detail. I will review the analysis done by the Planck collaboration and presented in the "Planck 2015 results. XIV. Dark energy and modified gravity" paper, which considered two broad cases: a DE which affects the background evolution and DE or MG...
Elisa Kay Pueschel
(University College Dublin)
15/12/2015, 14:00
Talk
The observed spectra of active galactic nuclei carry the imprint of gamma-ray interactions with the extragalactic background light (EBL). As gamma rays from an extragalactic source travel to the observer, pair production on the EBL plays a role in reprocessing the photons to lower energies, obscuring the intrinsic source spectrum. VERITAS, a ground-based imaging atmospheric-Cherenkov telescope...
Dr
Riccardo Ciolfi
(University of Trento and INFN-TIFPA)
15/12/2015, 14:00
Leading models relate short gamma-ray bursts (SGRBs) to a relativistic jet launched by the black hole (BH)-accretion torus system that can be formed in a binary neutron star (BNS) or a NS-BH binary merger. However, recent observations by Swift have revealed a large fraction of SGRB events accompanied by X-ray afterglows with durations $\sim10^2-10^5$ s, suggesting continuous energy injection...
Matteo Bachetti
(INAF/Osservatorio Astronomico di Cagliari)
15/12/2015, 14:00
Talk
M82 X-2, an ultraluminous X-ray source in M82, was recently shown to harbor an accreting neutron star. Its luminosity being ~100 times the Eddington limit for a neutron star, it poses some problems to the existing theoretical framework about accretion onto neutron stars.
I will talk about the proprieties and behavior of this source, how it was unveiled as a neutron star, the possible...
Norbert Schartel
(ESA)
15/12/2015, 14:00
Talk
With about 300 refereed papers published each year, XMM-Newton is one of the most successful scientific missions of ESA ever. Observations of Galactic as well as supermassive black holes, where relativistic effects have to be accounted for, play a major role in XMM-Newton's observing program. The main focus of the talk will be the discussion of scientific highlight results based on XMM-Newton...
Josefa Becerra Gonzalez
(NASA GSFC)
15/12/2015, 14:21
Talk
The high-frequency-peaked BL Lac object Markarian 501 is a very high energy (VHE, E>100 GeV) emitter located in our extragalactic neighborhood (z=0.034). The source can be detected in the VHE band during low state, what makes this target an ideal source for long-term multi-wavelength studies covering the entire electromagnetic spectrum. During a multi-wavelength campaign in 2014, the source...
Dr
Carmelita Carbone
(National Institute for Astrophysics - INAF)
15/12/2015, 14:21
I will present the first set of cosmological simulations produced within
the “Dark Energy and Massive Neutrino Universe” (DEMNUni) project. These
simulations are characterized by L=2 Gpc/h, Npart=2 x 2048^3, a baseline
LCDM-Planck cosmology, and four different total neutrino masses, Mnu=0,
0.17, 0.3, 0.53 eV, with a degenerate mass spectrum. They are the largest
N-body simulations to date...
Mr
Daniel Siegel
(Max Planck Institute for Gravitational Physics (Albert Einstein Institute))
15/12/2015, 14:21
Recent observations indicate that in a large fraction of binary
neutron star (BNS) mergers a long-lived neutron star (NS) may be
formed rather than a black hole. Unambiguous electromagnetic (EM) signatures of
such a scenario would strongly impact our knowledge on
how short gamma-ray bursts (SGRBs) and their afterglow radiation are
generated. Furthermore, such EM signals would
have...
Brynmor Haskell
(The University of Melbourne)
15/12/2015, 14:21
Neutron stars are an exceptional fundamental physics laboratory, and provide us with the only opportunity to study the strong interaction at high densities and low temperatures. These objects are, in fact, not only very dense (with central densities surpassing nuclear saturation density), but also cold, as their thermal energy is generally negligible compared to the Fermi energy of the...
Immacolata Donnarumma
(National Institute for Astrophysics - INAF)
15/12/2015, 14:21
Talk
We will report on the discovery potential of relativistic tidal disruption events with current and future instruments and its impact on the SuperMassive black hole mass function and the theory of jet formation.
Relativistic TDEs (or jetted TDEs) are a new class of sources, recently discovered by Swift/BAT, showing a significant radio counterpart of a common tidal disruption event. Observing...
Andrew Sutton
(NASA Marshall Space Flight Center)
15/12/2015, 14:25
Talk
There are now strong arguments that many ultraluminous X-ray sources (ULXs) are powered by super-Eddington accretion on to stellar remnant black holes. However, a key remaining question is: how are the classic sub-Eddington and new super-Eddington accretion states related? In an attempt to answer this, we present results from a systematic analysis of samples of the brightest thermal dominant...
Jason Dossett
(INAF - Osservatorio Astronomico di Brera)
15/12/2015, 14:26
Talk
There has been quite a bit of recent discussion about tension between CMB and weak lensing data sets, especially in the context of testing general relativity using modified growth parameters. We use a combination of cosmological data sets, including the CMB temperature anisotropy data from Planck, weak lensing tomography from CFHTLenS, and the WiggleZ galaxy power spectrum to place...
Dr
Koutarou Kyutoku
(RIKEN)
15/12/2015, 14:42
In recent years, mass ejection from compact binary coalescences has been getting a lot more attention. Neutron-rich material ejected from neutron stars during such a coalescence event are increasingly recognized as the most promising site of the rapid process (r-process) nucleosynthesis. Mass ejection will also be the primary agent for driving electromagnetic radiation from compact binary...
Dr
Simeon Bird
(Johns Hopkins University)
15/12/2015, 14:42
The massive neutrino background makes up a component of the dark matter, and as such affects the growth of large-scale structure, such as galaxy clusters. This affords us an opportunity to measure the neutrino mass. However, to do this we must accurately and efficiently characterize how neutrinos affect structure growth. I will describe a new method for including massive neutrinos in N-body...
Benoit Cerutti
(Princeton University)
15/12/2015, 14:42
Pulsars shine throughout the electromagnetic spectrum, from radio waves to energetic gamma rays. The radio emission is thought to originate from the discharge of the polar-cap and the formation of copious electron-positron pairs. Gamma rays are traditionally associated with particle acceleration in electrostatic gaps within the light cylinder. The recent development of global Particle-In-Cell...
Krzysztof Hryniewicz
(Nicolaus Copernicus Astronomical Centre)
15/12/2015, 14:42
Talk
Thanks to their thermal emission, Tidal Disruption Events (TDEs) were detected regularly in the soft X-rays and sometimes in the optical. Only few of them have been detected at hard X-rays: two are high redshift beamed events, one occurred at the core of a nearby galaxy and the last one is of a different nature, involving a compact object in the Milky Way.
The aims of presented work are to...
Pierre Colin
(MPI fuer Physik)
15/12/2015, 14:42
Talk
Rapid flux variabilities with time scales of minutes are regularly detected in the very high energy (VHE) gamma-ray emission of blazars during violent flaring periods. Those are generally explained by the classical shock-in-jet acceleration models, assuming a very large Doppler factor, which condenses the intrinsic multi-hours-scale variations into a few minutes for the observer on Earth. This...
PAOLO DA VELA
(INFN - National Institute for Nuclear Physics)
15/12/2015, 14:45
The origin of cosmic magnetic fields permeating galaxies and clusters is still unknown.To undertstand the origin and the evolution of the primordial cosmic magnetic fields we need to probe the existence and to characterize magnitude and correlation length of magnetic field in voids (Intergalactic magnetic field, IGMF), where pollution from magnetic fields associated to structures is expected...
Rudy Wijnands
(University of Amsterdam)
15/12/2015, 14:50
Talk
I will present our results of our studies on the spectral properties of neutron star low-mass X-ray binaries when they have accretion luminosities between 1e34 and 1e36 erg/s (roughly 0.01 - 1 percent Eddington). We found that their photon index increases with decreasing 0.5-10 keV luminosity (the spectrum softens). Such behaviour has been reported for individual sources, but we now...
Mario Ballardini
(University of Bologna)
15/12/2015, 14:53
Talk
We study the predictions for structure formation in an induced gravity
dark energy model
with a quartic potential. By developing a dedicated Einstein-Boltzmann
code, we study
self-consistently the dynamics of homogeneous cosmology and of linear
perturbations
without using any parametrization,
accurately recovering the quasi-static analytic approximation in the
matter dominated era.
We...
Dr
Melania Del Santo
(National Institute for Astrophysics - INAF)
15/12/2015, 15:02
Talk
In 2011 a new hard X-ray source, IGR J17361-4441, was discovered by INTEGRAL close the centre of the globular cluster NGC 6388.
Based on its peak luminosity, it was classified as very faint X-ray transient.
A Swift/XRT monitoring campaign showed an evident t^(-5/3) trend in the light curve,
and a thermal emission of ~0.08 keV that did not evolve significantly with time.
We...
Dr
Jaroslaw Dyks
(Nicolaus Copernicus Astronomical Center)
15/12/2015, 15:02
The knowledge of radio emission geometry is crucial
for interpreting their gamma-ray profiles, and for
establishing the orientation of their tilted magnetic field.
I will review the continually increasing evidence against the most popular (nested cone) radio beam geometry.
It will be shown that several features of pulse profiles,
which have normally been considered as signatures of the...
Floriana Zefi
(LLR - Ecole Polytechnique)
15/12/2015, 15:03
Talk
We report on evidence of simultaneous gamma-ray flaring from the BL Lac source B2 1215+30, detected by VERITAS (E > 100 GeV) and the Fermi Large Area Telescope (100 MeV < E <100 GeV). The source was observed by VERITAS during an exceptional flaring state in 2014 February 08. Investigations of flux variability in the energy range covered by Fermi-LAT, show that the GeV flare occurred...
Dr
Kazumi Kashiyama
(University of California, Berkeley)
15/12/2015, 15:03
Newborn black holes in collapsing massive stars can be accompanied by a fallback disc. The accretion rate is typically super-Eddington and strong disc outflows are expected. Such outflows could be directly observed in some failed explosions of compact (blue supergiants or Wolf-Rayet stars) progenitors, and may be more common than long-duration gamma-ray bursts. Using an analytical model, we...
Prof.
Reinhard Schlickeiser
(Ruhr University Bochum, Germany)
15/12/2015, 15:05
Two recent estimates of lower limits for the stochastic primordial magnetic fields are reviewed. The first estimate pioneered by Neronov and Vovk (2010) is based on GeV-TeV $\gamma $-ray observations of distant blazars by air-Cherenkov telecopes and the FERMI satellite. The generated $e^{\pm }$ pair beams from double photon collisions with the extragalactic background light have been expected...
Caroline Heneka
(Dark Cosmology Centre, Copenhagen)
15/12/2015, 15:19
Talk
Cold (or clustering) dark energy models present an interesting phenomonology in comparison to standard homogeneous dark energy.
We investigate the impact of cold dark energy on the background evolution, on the linear level, as well as at the nonlinear level on structure formation. For an accurate description at the nonlinear level, the halo mass function is carefully recalibrated to include...
Prof.
Tiziana Di Salvo
(University of Palermo)
15/12/2015, 15:20
Talk
We will present spectral and timing analysis of NuSTAR and XMM-Newton data of the Accreting Millisecond Pulsar SAX J1808.4-3658 during its latest outburst in April 2015.
We will discuss a high-quality broad band (2-80 keV) spectrum where the reflection component is clearly present, in line with previous results.
Using DDT XMM-Newton data, we derived updated values for the spin and the...
Lucia Pavan
(University of Geneva)
15/12/2015, 15:22
Despite jets are detected in all kind of accreting systems, bright and elongated jets are known to be formed also by isolated rotationally powered pulsars.
PSR J1101-6101 in the Lighthouse Nebula is an isolated pulsar which is powering a bright wind nebula and two jets, while travelling at supersonic velocity in the interstellar medium. Extending over 15 pc, the jets are more than 10 times...
Wenfei Yu
(Shanghai Astronomical Observatory)
15/12/2015, 15:22
Talk
When normal stars run close enough to the previously dormant supermassive black holes (SMBHs) at the centres of normal galaxies, they would be entirely or partly disrupted due to the tidal force, leading to the so-called tidal disruption events (TDEs). Part of the debris material will be accreted by the SMBHs later on. The accretion of the debris material would generate X-ray flares, which...
Francisco Villaescusa-Navarro
(OATS-INAF)
15/12/2015, 15:24
Neutrinos are described as fundamental particles by the standard model of particle physics. The fact that neutrinos are massive, as demonstrated by neutrino oscillations experiments, point towards physics beyond the standard model. Thus, one of the most important questions in modern physics is: which are the masses of the neutrinos? Current tightest constrain on the sum of the neutrino masses...
Frank Rieger
(MPIK and Univ. of Heidelberg)
15/12/2015, 15:24
Talk
The non-thermal radiation seen from astrophysical objects bears
witness to the presence of energetic charged particles that have
experienced efficient acceleration within these sources.
Shear flows are naturally expected in many of these environments.
Combined with new observational results in the radio and high energy
gamma-ray domain and with progress in our understanding of...
Lab Saha
(Nicolaus Copernicus Astronomical Center, Torun, Poland)
15/12/2015, 15:42
Poster
Average profiles
of some radio pulsars contain
weak emission components which cover large intervals of pulse phase
as well as localised emission or absorption features.
The polarisation-angle (PA) under such features exhibits
local distortions which cannot be explained through the rotating vector model
and other effects such as the special relativistic effects or
modification of...
Massimiliano Lattanzi
(University of Ferrara)
15/12/2015, 16:15
Cosmological observations represent a powerful tool to constrain neutrino physics. In particular, observations of the temperature and polarization anisotropies of the cosmic microwave background (CMB) have the potential to constrain the properties of relic neutrinos, and possibly of additional light relic particles in the Universe. Even if all current cosmological data are well in agreement...
Daniela Paoletti
(INAF and INFN)
15/12/2015, 16:15
Primordial magnetic fields (PMF) may represent the "progenitors"
of the fields we observe in large scale structures and their
study could open a new observational window on the early universe. The
Cosmic Microwave Background, thanks to its different probes,
represents one of the best laboratory to investigate and constrain the
nature of PMF. I will present the Planck 2015 constraints on...
Norbert S. Schulz
(Massachusetts Institute of Technology)
15/12/2015, 16:15
Talk
4U 1626-67 is an ultra-compact binary pulsar with a pulse period
of 7.7 sec and an orbital period of 40 min. Its X-ray spectrum
varies distinctively before and after torque
reversal episodes. 4U 1626-67 is a peculiar ultra-compact binary
in that it not only truncates its accretion disk at the magnetospheric
radius, but also emits Ne and O Doppler X-ray lines, The nature of
these lines...
Xavier Barcons
(Instituto de Física de Cantabria (CSIC-UC))
15/12/2015, 16:15
Talk
ESA’s *Athena* (Advanced Telescope for High-Energy Astrophysics) X-ray observatory mission, to be launched in 2028, will revolutionise our knowledge of the hot and energetic Universe. The X-IFU (X-ray Integral Field Unit) is one of the two instruments on the focal plane of its large X-ray telescope, providing sensitive spatially resolved high-resolution spectroscopy. *Athena*/X-IFU will...
Prof.
Jounghun Lee
(Seoul National University)
15/12/2015, 16:15
The radial velocities of the galaxies in the vicinity of a massive cluster shows deviation from the pure Hubble flow due to their gravitational interaction with the cluster. According to a recent study of Falco et al. with a high-resolution N-body simulation based on General Relativity (GR), the radial velocity profile of the galaxies located at distances larger than three times the virial...
Mr
Reginaldo Durazo
(Instituto de Astronomía, Universidad Nacional Autónoma de México)
15/12/2015, 16:35
For any MONDian extended theory of gravity where the rotation curves of spiral galaxies are explained through a change in physics rather than the hypothesis of dark matter, a generic dynamical behaviour is expected for pressure supported systems: an outer flattening of the velocity dispersion profile occurring at a characteristic radius, where both the amplitude of this flat velocity...
Gareth Hughes
(ETH Zurich)
15/12/2015, 16:35
Talk
The First G-APD Cherenkov Telescope (FACT) has pioneered the use of solid state photosensors (G-APD/SiPM) in astroparticle physics. Data-taking started in October 2011, and the system has operated remotely for over three years. G-APDs have proven to be very reliable and have enabled FACT to produce the first Crab nebulae spectra from such an instrument and collect large unbiased data sets on...
Jérôme Pétri
(Université de Strasbourg)
15/12/2015, 16:35
Pulsar magnetospheres are shaped by ultra-relativistic electron/positron plasmas flowing in a strong magnetic field and subject to strong gravitational fields. The former induces magnetospheric currents and space charges responsible for the distortion of the electromagnetic field based on pure electrodynamics. The latter induces other perturbations in these fields based on space-time...
Dr
Filippos Koliopanos
(Research Institute in Astrophysics and Planetology (IRAP), Toulouse, France)
15/12/2015, 16:35
Talk
We have discovered strong indications of a correlation between the appearance of the Fe Kα emission line in the spectrum of the X-ray pulsar 4U 1626-67 and its luminosity and shape of its pulse profile. Spectroscopic analysis of the latest, simultaneous Chandra/RXTE observation of 4U 1626-67, revealed the presence of a narrow Fe Kα emission line. The observation was performed when the source...
Dr
Kerstin Kunze
(University of Salamanca)
15/12/2015, 16:35
The presence of large scale magnetic fields at different epochs can be probed by their impact on different observables such as the CMB spectrum, primary and secondary CMB anisotropies, matter power spectrum and 21cm line emission. I will give an overview of these effects together with constraints from current and future experiments.
Dr
Wako Ishibashi
(ETH Zurich)
15/12/2015, 16:40
Talk
Black holes in active galactic nuclei (AGN) respond to the accretion process by feeding back energy and momentum into the surroundings. Such AGN feedback is generally invoked to quench star formation in host galaxies, either by heating or removing the ambient gas. However, feedback from the accreting black hole may also play other roles in galaxy evolution.We consider the role of radiation...
Dr
Marina Manganaro
(IAC)
15/12/2015, 16:55
Talk
S5 0716+714 is a well known BL-Lac object, located at a redshift of z=0.31. The discovery in the Very High Energy band (VHE, E> 100 GeV) by MAGIC happened in 2008, when Fermi data in the High Energy (HE, 100 MeV < HE<100 GeV) were not yet available. In January 2015 the source went through the brightest optical state ever observed, triggering MAGIC follow-up and a VHE detection with ~13 sigma...
Prof.
Rosario Iaria
(Univ. di Palermo - DSFC)
15/12/2015, 16:55
Talk
The ultra-compact dipping source XB 1916-053 has an orbital period of
close to 50 min and a companion star with a very low mass (less
than 0.1 M$_{\odot}$). The known orbital period derivative
($1.5(3) \times 10^{-11}$ s/s) is extremely large and can be
explained by invoking an extreme, non-conservative mass transfer
rate that is not
easily justifiable. We extended the...
Dr
Levon Pogosian
(Simon Fraser University)
15/12/2015, 16:55
I will discuss CMB signatures of primordial magnetic fields, some of the existing constraints, and what can be expected from future CMB experiments.
David Moore
(Stanford University)
15/12/2015, 16:55
We are developing a novel technique to search for non-Newtonian gravitational forces at micron length scales using optically levitated dielectric microspheres. At high vacuum, dissipation of the microsphere's motion due to residual gas collisions becomes small, allowing sub-attonewton force sensitivity. As a first demonstration of the ability to perform sensitive force measurements with...
Dr
Antonella Garzilli
(Leiden University)
15/12/2015, 16:57
We reconsider the problem of determining the warmness of dark matter
from the growth of large scale structures. In particular, we have
re-analyzed the previous work of Viel et al 2013, based on high
resolution Lyman-alpha forest spectra. In fact, the flux power
spectrum exhibits a cut-off below ~ 1.5 Mpc/h, this may be explained
by the temperature of the intergalactic medium (IGM) or be...
Prof.
Lucio Mayer
(University of Zurich)
15/12/2015, 17:00
Talk
We present the latest developments of the merger-driven scenario for supermassive black hole formation originally developed in Mayer et al. (2010,
Nature, 466. 1082). We show how including realistic radiation physics in mergers of protogalaxies driven from cosmological initial conditions strengthens the proposal that supermassive nuclear clouds may form in only a few 10^8 yr in the nucleus of...
Dr
Fiamma Capitanio
(IAPS-INAF)
15/12/2015, 17:15
Talk
4U 1630–472 is a recurrent X-ray transient classified as a black hole candidate from its spectral and timing properties. One of the peculiarities of this source is the presence of regular outbursts
with a recurrence period between 600 and 730 d that has been observed since the discovery of the source in 1969. We report on a comparative study, performed with INTEGRAL and RXTE, of the spectral...
Hector Javier Hortua
(Universidad Nacional)
15/12/2015, 17:15
Poster
In this work we compute the temperature-polarization correlations
(C_l^(TB) and C_l^(EB)) in the cosmic microwave background (CMB) generated by the presence of causal primordial magnetic fields with a helical contribution.
We analize the effect of an infrared cutoff in the power spectrum of causal fields on the cross-correlation and we compare our result with previous work.
Mikhail Belyaev
(UC Berkeley/TAC)
15/12/2015, 17:15
We perform 2.5D axisymmetric simulations of the pulsar magnetosphere (aligned dipole rotator) using the charge conservative, relativistic, electromagnetic particle in cell code PICsar. The particle in cell method is a powerful tool for studying the pulsar magnetosphere, because it can handle the force-free and vacuum limits as well as magnetic reconnection. In particular, dissipative regions...
Giovanna Pedaletti
(DESY)
15/12/2015, 17:15
Talk
The blazar S4 0954+65 (at a redshift of z=0.368) underwent an exceptionally high state in optical during January and February 2015, as revealed by the Tuorla and St.Petersburg University blazar monitoring programs: a brightening of more than 3 magnitudes in the R-band from the average monitored states. Simultaneous data from the Fermi-LAT satellite at high energy gamma rays (100MeV < E <...
Vivian Poulin
(Unite Reseaux du CNRS (FR))
15/12/2015, 17:18
After a recap of the standard e.m. cascade theory, I will discuss a loophole
that can have a large effect in the early universe, notably in altering
primordial nucleosynthesis bounds on electromagnetically decaying relic particles.
I will finally show how this may greatly simplify the possibility to address
the long-standing "lithium problem" in terms of new physics models, and solve it...
Prof.
andres escala
(Universidad de chile)
15/12/2015, 17:20
Talk
By using AMR cosmological hydrodynamic N-body zoom-in simulations, with the RAMSES code, we studied the mass transport processes onto galactic nuclei from high redshift up to z~6. Due to the large dynamical range of the simulations we were able to study the mass accretion process on scales from ~50 kpc to ~pc. The SMBHs are modelled as a sink particles at the center of our galaxies, which ...
Mr
Jurgen Mifsud
(Consortium for Fundamental Physics, School of Mathematics and Statistics, University of Sheffield)
15/12/2015, 17:25
We study a theory in which the electromagnetic field is disformally coupled to a scalar field, in addition to a usual non--minimal electromagnetic coupling. We show that disformal couplings modify the expression for the fine--structure constant, $\alpha$. As a result, the theory we consider can explain the non--zero reported variation in the evolution of $\alpha$ by purely considering...
Jérôme Pétri
(Université de Strasbourg)
15/12/2015, 17:35
Geodetic precession has been observed directly in the double-pulsar PSR J0737-3039. Its rate has even been measured and agrees with predictions of general relativity. Very recently, the double pulsar has been detected in X-rays and gamma-rays. This fuels the hope observing geodetic precession in its high-energy pulse profile. Unfortunately, the geometric configuration of the binary renders any...
Josefa Becerra Gonzalez
(NASA GSFC)
15/12/2015, 17:35
Talk
The detection of Flat Spectrum Radio Quasars (FSRQs) in the Very High Energy (VHE, E$>$100 GeV) range is challenging, mainly due to their steep soft spectra in this energy band. Thus far, only five FSRQs are known to be VHE gamma-ray emitters, all of which have been detected by the MAGIC telescopes, which made the first VHE detection of four of them. Observations in the VHE band are crucial to...
Lorenzo Ducci
(University of Tuebingen)
15/12/2015, 17:35
Talk
Glitches have been observed in isolated pulsars, while a
clear detection in accretion-powered X-ray pulsars is still lacking.
We use the "snowplow" model for pulsar glitches of Pizzochero
(2011) and starquake models to determine for the first time the
expected properties of glitches in accreting pulsars. We also
investigate the possibility that anti-glitches occur in accreting
pulsars...
Pablo Fernández de Salas
(IFIC - CSIC/Universidad de Valencia)
15/12/2015, 17:39
We have performed a new numerical calculation of the decoupling process of neutrinos in the early Universe, including the values of all mixing parameters from a recent analysis, taking into account the full set of differential equations for the neutrino density matrices (equivalent to the occupation numbers for mixed neutrinos). Our results are important for fixing the radiation content of the...
Dr
Sergey Sazonov
(Space Research Institute, Moscow, Russia)
15/12/2015, 17:40
Talk
We have utilized a local AGN sample from the INTEGRAL all-sky hard X-ray survey to investigate if the well-known declining trend of the fraction of obscured AGN with increasing luminosity is mostly an intrinsic or selection effect. We show that in addition to negative bias, due to absorption in the torus, in finding obscured AGN, there is positive bias in finding unobscured AGN, due to Compton...
Diego Blas Temino
(CERN)
15/12/2015, 17:45
After briefly explaining why Lorentz violating theories of gravity are interesting for quantum gravity, I will discuss how they can be tested with current astrophysical and cosmological observations.
Anastasios Fragkos
(University of Geneva)
15/12/2015, 17:51
Talk
In recent years, an increasing number of proper motions have been measured for Galactic black hole (BH) X-ray binaries (XRBs). When supplemented with accurate determinations of the component masses and spin rates, orbital period, and donor luminosity and effective temperature, these kinematical constraints harbor a wealth of information on the systems’ past evolution. We developed an analysis...
Antonio Stamerra
(INAF-OATo / SNS-Pisa)
15/12/2015, 17:55
Talk
For the first time a gamma-ray and multiwavelength nearly-periodic oscillation in an active galactic nucleus is reported using the Fermi Large Area Telescope (LAT). A quasi-periodicity in the gamma-ray flux (E>100 MeV and E>1 GeV) is observed from the well-known GeV/TeV BL Lac object PG 1553+113 (Ackermann et al. submitted). The significance of the 2.18 +/- 0.08 year-period gamma-ray...
Guillaume Belanger
(ESA)
15/12/2015, 17:55
Poster
We present here the results of an analysis of 15 years of regular XMM-Newton EPIC pn observations of the Crab pulsar. The analysis of its pulse profile is based on a multi-harmonic decomposition using a new periodogram statistic which is ideally suited for studying the details of the characteristics of peaked pulse profiles such as the Crab’s, especially in time-tagged event data. The...
Florian Führer
(Institut für Theoretische Physik, Universität Heidelberg)
15/12/2015, 18:00
I will present a new first principle approach for higher order perturbation theory for hot and warm dark matter in large scale structure. The approach is based on a non-linear generalization of Gilbert's equation. Combined with standard perturbation theory, it allows to calculate N-point statistics of density perturbations in mixed cold+hot dark matter cosmologies. I apply the theory to...
Kadri Yakut
(University of EGE),
Tuğçe İÇLİ
15/12/2015, 18:08
Poster
In this study, we present angular momentum loss mechanism through gravitational radiation for the selected system with neutron stars and gravitational radiation time-scale is estimated for them.
Dr
Lubos Neslusan
(Astronomical Institute, Slovak Academy of Sciences, 05960 Tatranska Lomnica, Slovakia)
15/12/2015, 18:10
In 2011, Jun Ni published solution of the equations in the classical Tolman-Oppenheimer-Volkoff (TOV) modeling of spherically symmetric neutron star. The Ni's solution implies no upper-mass limit and the outer surface of modeled object always appears to be above the event horizon. In fact, Ni found an infinite variety of sets of the TOV-problem solutions. The original Oppenheimer-Volkoff...
Dr
Sergio Mendoza
(Instituto de Astronomia, Universidad Nacional Autonoma de Mexico (UNAM))
15/12/2015, 18:13
A metric extension of gravity based on the Tully-Fisher law is
presented. It will be shown that the Tully-Fisher law extends from the
dynamics of globular clusters up to the dynamics of groups of galaxies
and how it can be consider as a modified version of Kepler's third law.
With it, it will be shown how at second perturbation order lensing can
be fully understood and that the...
Gareth Hughes
(ETH Zurich)
15/12/2015, 18:15
Talk
PG 1553+113 is a blazar with an uncertain redshift detected at very high energies (VHE; E > 100 GeV) both during high and quiescent flux states. The Fermi/LAT collaboration
recently reported the detection of a ~2-year modulation of the integral flux emitted in both optical and high-energy (HE) gamma rays(Stamerra et al. at this conference). Interestingly, one of the physical scenarios that...
Hussain Gohar
(University of Szczecin, Poland)
15/12/2015, 18:16
We formulate the basic framework of thermodynamical entropic force cosmology which allows
variation of the gravitational constant G and the speed of light c. Three different approaches to the
formulation of the field equations are presented. Some cosmological solutions for each framework
are given and one of them is tested against combined observational data (supernovae, BAO, and
CMB)....
Prof.
Pradyumn Kumar Sahoo
(Birla Institute of Technology and Science-Pilani, Hyderabad Campus)
15/12/2015, 18:19
A class of Kaluza-Klein cosmological models in $f(R,T)$ theory of
gravity have been investigated. In the work, we have considered the
functional $f(R,T)$ to be in the form $f(R,T)=f(R)+f(T)$ with
$f(R)=\lambda R$ and $f(T)=\lambda T$. Such a choice of the
functional $f(R,T)$ leads to an evolving effective cosmological
constant $\Lambda$ which depends on the stress energy tensor....
Ingyin Zaw
(NYU Abu Dhabi)
15/12/2015, 18:20
Poster
NGC 4945, one of the closest starburst-AGN presents a unique laboratory for testing the interplay between AGN accretion and star formation. It is the brightest extragalactic source of hard X-rays but is highly obscured below 10 keV. Its proximity allows for mapping the inner-most parsec of the galactic nucleus using very long baseline interferometry of the unobscured 22 GHz water maser...
Ernesto Barrientos Rodríguez
(Universidad Nacional Autónoma de México)
15/12/2015, 18:22
In this work we construct a relativistic extension of the MODified
Newtonian Dynamics (MOND) in the metric formalism $f(\chi)$ using the
Palatini approach. We show that a simple power law: $f(\chi)=\chi^b$,
with $b = 3/2$ corresponds to the non-relativistic form of MOND.
Amongst the many approaches proposed to extend MOND to a relativistic
regime, the Palatini metric formalism discussed...
Dr
Erika Benitez
(Instituto de Astronomia, Universidad Nacional Autonoma de Mexico (UNAM)), Dr
Sergio Mendoza
(Instituto de Astronomia, Universidad Nacional Autonoma de Mexico)
15/12/2015, 18:23
Poster
A model independent power spectrum light curve analysis in the optical,
hard X-ray and gamma-rays of the blazar MRK 421 shows clear evidence
for a periodicity of approximately 400 days. A subsequent full maximum
likelihood analysis fitting an eclipse model confirms this periodicity
with a consistent phase for the bands analysed. The most parsimonious
physical mechanism to which this...
Dr
Hossein Ghaffarnejad
(Semnan University of IRAN)
15/12/2015, 18:25
Combinations of Lovelock polynomials $R^2,R_{\mu\nu}R^{\mu\nu}$ and
$R_{\mu\nu\eta\delta}R^{\mu\nu\eta\delta}$ is added with
Einstein-Hilbert action to obtain interior metric of an anisotropic
spherically symmetric collapsing (ASSC) stellar cloud. We assume
that time dependent interior metric of the ASSC cloud is flat
Minkowski at beginning of the collapse. We solved linearized...
Omar Kurtanidze
(Abastumani Observatory)
15/12/2015, 18:35
Poster
To study optical variability of extragalactic objects, namely VHE blazars, we are conducting in Abastumani Observatory since 1997 a long-term campaign using dedicated telescopes, which allowed to collect ~300 000 CCD frames during 2 800 nights. This extensive monitoring campaign over 100 blazars during five years was carried out in BVRI bands and later on from 2002 mainly in R band using the...
Graziano Rossi
(Sejong University)
15/12/2015, 18:43
Poster
We present joint constraints on the number of effective neutrino species Neff and the sum of neutrino masses, using a technique based on state-of-the-art hydrodynamical simulations with massive neutrinos, which allows one to exploit the full information contained in the one-dimensional Lyman-Alpha forest flux power spectrum complemented by additional cosmological probes. Our results provide...
Prof.
Michael KRAMER
(Max-Planck-Institut fuer Radioastronomie)
15/12/2015, 19:30
Talk
Einstein’s theory of general relativity revolutionised our understanding of the cosmos, its origin and its fate. Not surprisingly, it is one of the best tested theories, and so far all of its predictions have been confirmed. Einstein himself did not know many of the tests we can do today, 100 years after general relativity was presented by him. The most modern tests involve ultra-compact...
Prof.
Alessandra Buonanno
(Max Planck Institute for Gravitational Physics)
16/12/2015, 09:00
Talk
Gravitational waves were first predicted by Albert Einstein in 1916 on the
basis of his theory of general relativity. In the next five years ground-based
interferometers, such as advanced LIGO, advanced Virgo and KAGRA, are likely
to provide the first direct detections of gravitational waves from binary systems composed
of black holes and/or neutron stars. In this talk, we review the...
Prof.
Luis Lehner
(Perimeter Institute)
16/12/2015, 09:35
Talk
Compact binary systems are copious producers of gravitational waves and
are also expected to radiate strongly electromagnetically. This talk will
describe several processes --intrinsically requiring the strongly gravitating/highly
dynamical behaviour of the system-- that can yield observable signals in a variety
of frequencies. Moreover, we will discuss how such radiation might prove...
Prof.
Michael KRAMER
(Max-Planck-Institut fuer Radioastronomie)
16/12/2015, 10:10
Talk
The radio sky is a fascinating laboratory for a very wide range
of physics. The laws of nature can be probed at a fundamental
level, in particular when observing the most extreme matter in
the observable universe - neutron stars. When they are visible
as radio pulsars they can act as cosmic clocks that become
especially interesting if they have a binary companion. Indeed,
binary pulsars...
Prof.
Carlo Rovelli
(Université de la Méditerranée, Marseille)
16/12/2015, 11:20
Talk
Black holes are well understood in their classical dynamics or as background geometry for quantum fields. But their quantum gravitational properties remain elusive. These are crucial to understand what happens to the matter falling inside, and to know the holes' long term stability. There are a number of recent results and ideas on this issue, including the firewall theorem, Planck stars,...
Ms
Giulia Cusin
(University of Geneva)
16/12/2015, 14:00
We introduce some recently proposed non-local infrared modifications of general relativity. We discuss which are the motivations to introduce non-localities in a theory of gravity. We then present a particular class of models which has been recently shown to be cosmologically viable, with an extremely good compatibility with cosmological data. We present the general features of such a class...
Dr
Adam Ingram
(University of Amsterdam)
16/12/2015, 14:00
Talk
Accreting stellar mass black holes often show a quasi-periodic oscillation (QPO) in their X-ray flux with a period that slowly drifts from ~10s to ~0.05s and an iron emission line in their X-ray spectrum. The iron line is generated by fluorescent re-emission, by the accretion disk, of X-ray photons originating in the innermost hot flow. The line shape is distorted by relativistic motion of the...
Massimo Cappi
(National Institute for Astrophysics - INAF)
16/12/2015, 14:00
Talk
I will briefly review the evidence for high-velocity (mildly relativistic) and massive winds in Active Galactic Nuclei. I will then highlight some new recent results obtained in X-rays (mostly using deep XMM and Chandra observations) and at multi-frequencies for both low-z AGNs and high-z QSOs. Among other things, these studies indicate that massive, high-velocity, outflows may be more common...
Dr
Jason Hessels
(University of Amsterdam)
16/12/2015, 14:00
Talk
As the most rapidly rotating stars known, millisecond pulsars continue
to enjoy great scientific interest and broad impact. They acquire
their millisecond rotational periods through mass transfer from a
binary stellar companion; via their radio, X-ray and/or gamma-ray
pulsations we can precisely time their spin rate and orbital motion
around a companion object (or even multiple...
Christos Tsagas
(Aristotle University of Thessaloniki)
16/12/2015, 14:00
Inflation has long been thought as the best way of producing large-scale primordial magnetic fields. To achieve fields strong enough to seed the galactic dynamo, most of the generation mechanisms operate outside conventional electromagnetic theory, which is typically restored after the end of the de Sitter phase. Breaking away from standard electromagnetism can lead to substantially stronger...
Jill Chevalier
(LAPP)
16/12/2015, 14:00
Talk
The High Energy Stereoscopic System H.E.S.S. is an array of 5 Imaging Atmospheric Cherenkov Telescopes located in the Khomas Highland, Namibia. The first four 12m-diameter telescopes are operating since 2003 and a fifth telescope (a 28m diameter dish) had been added to the array in 2012 improving the sensitivity of the array towards lower energies. In this talk, I will present highlight of...
Tania Regimbau
(Observatoire de la Côte d'Azur)
16/12/2015, 14:00
According to various cosmological scenarios, we are bathed in a stochastic background of gravitational waves generated in the first instants after the Big Bang. Detection of this background would have a profound impact on our understanding of the evolution of the Universe, as it represents a unique window on the very early Universe and on the physical laws that apply at the highest energy...
Jorge Ovalle
(Simon Bolivar University)
16/12/2015, 14:21
In the context of extra-dimensional gravity, as the Randall-Sundrum brane-world, a consistent extension of the minimal geometric deformation approach (MGD) is used to study the exterior spacetime
around spherically symmetric self-gravitating system. A modified Schwarzschild geometry is obtained and new black hole solutions are shown. A possible extension of this approach in $F(R)$ theories is...
Elinore Roebber
(McGill University)
16/12/2015, 14:21
We use large N-body simulations and empirical scaling relations between dark matter halos, galaxies, and supermassive black holes to estimate the formation rates of supermassive black hole binaries and the resulting low-frequency stochastic gravitational wave background (GWB). We find that uncertainty in the astrophysical scaling relations systematically changes the amplitude of the GWB by a...
Dr
Alexey Boyarsky
(Leiden University (NL)),
Oleg Ruchayskiy
(Ecole Polytechnique Federale de Lausanne (CH))
16/12/2015, 14:21
If chiral (left-right) asymmetry is present in the plasma,
the electric current, parallel to the magnetic field, appears. This is known as
"*chiral magnetic effect*". We demonstrate that this effect changes the dynamics of the magnetized relativistic plasma and present the proper equations of chiral relativistic magnetohydrodynamics, containing a new, axion-like, degree of freedom. There...
Luigi Pacciani
(IAPS/INAF)
16/12/2015, 14:22
Talk
High-Energy gamma-ray flares (E$>$10 GeV) of Flat Spectrum Radio Quasars (FSRQ) give us strong constraints of jet-physics, and of the surrounding-medium.
We performed the first study of these flares, examining FERMI-LAT archival-data, and triggering $\sim$40 ToO-observations from near-ir to TeV (e.g., for PKS 1441+25),
at the occurrence of new flares.
We identified $\sim$260 gamma-ray...
Eugenio Bottacini
(Stanford University)
16/12/2015, 14:25
Talk
Most galaxies undergo one or more eras of Active Galactic Nucleus (AGN) activity throughout their existence. During this era their environment around the central super-massive black hole emits from X-ray to soft gamma-ray energies. Therefore these spectra and their features carry the information of the extreme gravitational conditions. However these spectral features can be transient and...
Achim Gütlein
(Austrian Academy of Sciences)
16/12/2015, 14:25
Talk
CRESST-II is a direct dark matter search using cryogenic detectors based on calcium tungstate. Due to their light nuclei and low energy thresholds these detectors allow for a high sensitivity for dark-matter particles with low masses.
We present data corresponding to an exposure of 52 kg-days obtained by one single detector module with a very low energy threshold of 307 eV for nuclear...
Joeri van Leeuwen
(ASTRON / U. Amsterdam)
16/12/2015, 14:30
Talk
PSR J1906+0746 is a young pulsar in the relativistic binary with the second-shortest known orbit, of 3.98 hours. We will present a timing study based on five years of observations, conducted with the 5 largest radio telescopes in the world, aimed at determining the companion nature (van Leeuwen et al. 2015). Through the measurement of three post-Keplerian orbital parameters we find the pulsar...
Dr
Lucas Lombriser
(University of Edinburgh)
16/12/2015, 14:43
Modifications of gravity arising in the presence of a nonminimally coupled scalar field and capable of accelerating the expansion of our Universe can be suppressed at the linear level of cosmological perturbations, only introducing deviations from concordance cosmology at the largest observable scales. I will classify the theory space capable of this mechanism in the effective field theory of...
Vivian Poulin
(Unite Reseaux du CNRS (FR))
16/12/2015, 14:45
Talk
Cosmology, and especially the CMB anisotropies, has been proved to be a powerful tool in the quest for pinning down the nature of Dark Matter (DM).
In this talk, I will review how it is possible to get very competitive constraints on the lifetime and the fraction of unstable DM particles, as well as constraints on the annihilation cross section, using either purely gravitationnial...
Lorenzo Natalucci
(Istituto di Astrofisica e Planetologia Spaziali, INAF)
16/12/2015, 14:47
Talk
The black hole binary V404 Cygni exhibited an unprecedently bright outburst on 2015, June 15. Since then, many space and ground observing facilities monitored the flux from the source during several weeks, until its decline to a near-quiescent state in late July-August. The source was extremely variable at all wavelenghts. The radio versus X-ray flux variations are reminiscent of the already...
John Quinn
(University College Dublin)
16/12/2015, 14:50
Talk
VERITAS is a very-high-energy (VHE, E$≳$100 GeV) gamma-ray observatory that has been in full scientific operation since 2007. A series of upgrades has provided significant sensitivity increases and improved low-energy performance, greatly enhancing the scientific capabilities of VERITAS. The VERITAS science program includes a full complement of observations of Galactic (pulsars,...
Marina Berezina
(Max Planck Institute for Radio Astronomy)
16/12/2015, 14:55
Talk
We report on the two new MSP discoveries from the High Time Resolution Universe survey for pulsars and fast transients in the northern hemisphere (HTRU-North), being conducted with the 100-m Effelsberg telescope (Barr et al, 2013). The survey has so far resulted in the total number of 17 new pulsars. Here we present timing solutions for PSR J2045+3633 and PSR J2053+4650, both binary systems...
Dr
Thomas Russell
(ICRAR/Curtin University)
16/12/2015, 15:02
Talk
There is a universal connection between the accretion and ejection phenomena that are observed in black holes across the mass scale. Quantifying this relationship is the first step in understanding how jets are launched, accelerated and collimated. X-ray binaries are ideal systems to study this relationship, as they evolve on human timescales. In outburst, their luminosities increase by...
Mark Hindmarsh
(University of Sussex)
16/12/2015, 15:03
Recent numerical simulations have demonstrated that the most important source of gravitational radiation from a thermal first order phase transition in the early Universe is the sound waves it produces. I outline the theory of the acoustic production of gravitational waves from phase transitions, showing how both the amplitude and shape of the power spectrum can be simply understood....
Axel Brandenburg
(Nordita)
16/12/2015, 15:03
There was a time when primordial magnetic fields posed a serious
contender to explaining the origin of magnetic fields in galaxies
and on larger scales. This has changed drastically during the past
three decades, and now the dynamo origin of galactic magnetic fields is
unchallenged. Nevertheless, primordial magnetic fields might still be an
attractive possibility to explaining magnetic...
Wessel Valkenburg
(Leiden University)
16/12/2015, 15:04
I will present a novel description for setting initial particle displacements and field values under arbitrary metric theories of gravity, for perfect and imperfect fluids with arbitrary characteristics. We extend the Zel'dovich Approximation to nontrivial theories of gravity, and show how scale dependence implies curved particle paths, even in the entirely linear regime of perturbations....
Sam Young
(University of Sussex)
16/12/2015, 15:05
Talk
There are strong theoretical arguments which suggest that primordial black holes (PBHs) may have formed from the collapse of large over-densities during the radiation dominated epoch shortly after the end of inflation. Because these black holes can form on much smaller scales than those visible from the CMB or large-scale structure, they have historically been used to place a unique constraint...
Dr
George Chartas
(College of Charleston)
16/12/2015, 15:12
Talk
We present a promising new technique (g-distribution method) for measuring the innermost stable circular orbit (ISCO), the inclination angle (i), and the spin of a supermassive black hole. The g-distribution method involves measurements of the distribution of the energy shifts of the relativistic iron line emitted from the accretion disk of a supermassive black hole that is microlensed by...
Dr
Robert Lauer
(University of New Mexico)
16/12/2015, 15:15
Talk
The High Altitude Water Cherenkov (HAWC) observatory is an extensive air shower detector optimized for studying gamma rays with energies between 100 GeV and 100 TeV.
Located at an elevation of 4100 m near Puebla, Mexico, the array consists of 300 water tanks instrumented with 4 photo-multiplier tubes each and was completed in March 2015.
A wide instantaneous field of view of ~2 sr and a duty...
Prof.
Wim Hermsen
(SRON Netherlands Institute for Space Research, Utrecht, The Netherlands)
16/12/2015, 15:15
Talk
With XMM-Newton, GMRT and LOFAR observations of the mode-changing near-aligned pulsar PSR B0943+10 we discovered synchronous switching in the radio and X-ray emission properties (Hermsen et al. 2013). These extraordinary findings were reported to support radio indications for rapid, global changes to the conditions in the magnetosphere. However, there is still no consistent interpretation for...
Dr
Marek Nikolajuk
(University of Bialystok)
16/12/2015, 15:22
Talk
The microquasar GRS 1915+105 features well known spectral states that were never extensively studied up to the MeV range, where key spectral diagnostics are expected. We present hard X-ray observations obtained in 15 Msec with Swift/BAT and INTEGRAL and spectra collected during different states up to 400 keV. These spectra can be successfully fitted by the EQPAIR model revealing continuous...
David Weir
(University of Stavanger)
16/12/2015, 15:24
We present large-scale numerical simulations of the gravitational radiation produced by a first order thermal phase transition in the early universe. The dominant source of gravitational waves is sound waves generated by the expanding bubbles of the low-temperature phase. The resulting gravitational wave power spectrum has a power-law form between scales set by the average bubble separation...
Andrey Beresnyak
(Naval Research Laboratory)
16/12/2015, 15:24
MHD Turbulence is a strongly nonlinear dynamics of conductive fluids, e.g. plasma. Recent progress in theory regarding almost all basic regimes of this dynamics -- from how the magnetic field is generated (dynamo problem), to how turbulence is decaying, to what are the asymptotic scaling laws, allowed us to proceed with more observationally motivated questions. One of them is why almost all...
Jens Niemeyer
(Goettingen University)
16/12/2015, 15:25
Talk
Light scalar fields such as ultra-light axions (ULAs) are dark matter candidates which suppress the growth of perturbations on scales below their de Broglie wavelength and predict solitonic halo cores owing to their quantum pressure support. They therefore give rise to new phenomenology in large-scale structure formation and galaxy evolution, including a potential solution to the cusp-core and...
Masaaki Takahashi
(AIchi University of Education)
16/12/2015, 15:33
Poster
The formation of standing magnetohydrodynamical (MHD) shocks by accreting plasma in a black hole magnetosphere is studied. The black hole magnetosphere would be formed around a black hole with an accretion disk. The global magnetic field lines would be originated by currents in the accretion disk and its corona, and then some part of magnetic field lines would lead to the event horizon. Along...
Ms
Paola Rioseco
(IFM-UMICH)
16/12/2015, 15:36
Poster
We analyze the accretion of gas into a black hole background space-time in the context of relativistic kinetic theory. The state of the gas is described by a distribution function which has to satisfy the general relativistic Boltzmann equation.
In the first part of this work, we describe a method to find the most general solution of this equation in the collisionless case.
In the second...
Ms
Dolunay Kocak
(University of Ege),
Kadri Yakut
(University of EGE)
16/12/2015, 15:39
Poster
In this study, we present angular momentum loss mechanism through gravitational radiation for the selected X-ray binary systems. Gravitational radiation time-scale is estimated for each selected system. In addition, their gravitational wave amplitudes are also estimated and their detectability with gravitational wave detectors has been discussed.
Jörg Paul Rachen
(IMAPP / Radboud University Nijmegen)
16/12/2015, 15:42
Poster
We present time-resolved broad-band spectra of a complete
sample of blazars, selected by showing flat radio spectra up to 143
GHz, taken from observations with Planck, the Effelsberg 100m
telescope, and the IRAM 30m telescope. Dedicated Effelsberg
observations have been focused on times within two months around
Planck single survey scans of each source, with a cadence of 2-4 weeks
during...
Mr
Varadarajan Parthasarathy
(N. Copernicus Astronomical Center)
16/12/2015, 15:42
Poster
Our research focuses on axisymmetric hydrodynamical simulations. The models implemented are *thinner* tori and *thicker* torus in equilibrium around a non-rotating black hole. The tori were constructed with a constant distribution of angular momentum obtained from Kluzniak-Lee (a pseudo-Newtonian) potential. Epicyclic motion were triggered by adding sub-sonic velocity fields; radial, vertical...
Dr
Kyle Parfrey
(Lawrence Berkeley National Laboratory)
16/12/2015, 16:15
Talk
We propose a scenario for launching relativistic jets from rotating black holes, in which small-scale magnetic flux loops, sustained by disc turbulence, are forced to inflate and open by differential rotation between the black hole and the accretion flow. This mechanism does not require a large-scale net magnetic flux in the accreting plasma, whose presence in the environment of the central...
Laura BERNARD
(Université de Paris 6 - Pierre et Marie Curie)
16/12/2015, 16:15
The only consistent linear theory for a massive spin-2 field on a flat space-time has been known for a long time as being the Fierz-Pauli theory. Its promotion to a non-linear theory, although essential, has long been thought impossible because of the appearance of the Boulware-Deser (BD) ghost. Recently, de Rham, Gabadadze and Tolley (dRGT) proposed a family of massive gravity theories, free...
Thomas Tauris
(Uni. Bonn)
16/12/2015, 16:15
Talk
Radio millisecond pulsars (MSPs) have been spun-up to very high rotation frequencies
via accretion of mass and angular momentum from a companion star in a binary system.
In this talk, I will review the formation of MSPs and discuss recent observational
and theoretical challenges in understanding their formation and evolution via the
standard recycling scenario. I will discuss MSP...
Dr
Johann Cohen-Tanugi
(LUPM, Université de Montpellier & CNRS/IN2P3)
16/12/2015, 16:15
Talk
Indirect dark matter (DM) searches rely on detection of stable by-products of DM interactions to search for a signal of this elusive component of the Universe. Among these final products, gamma rays have recently played a major role in understanding the nature of the DM particle. This contribution reviews the current status of indirect DM searches with the Large Area Telescope, the main...
Nicola Tamanini
(CEA - France)
16/12/2015, 16:15
In this talk I will consider the application of eLISA as a probe of the late-time cosmological expansion. In particular I will first review the concept of standard sirens and how these can be used to investigate the distant-to-redshift relation. I will then discuss the best strategies to obtain as many standard sirens as possible, taking into account what kinds of electro-magnetic counterparts...
Dr
Andrey Saveliev
(University of Hamburg/Keldysh Institute)
16/12/2015, 16:15
In order to give a consistent picture of cosmic, i.e. galactic and extragalactic, magnetic fields, different approaches are possible and often even necessary. Here we present three of them: First, a semianalytic analysis of the time evolution of primordial magnetic fields from which their properties and, subsequently, the nature of present-day intergalactic magnetic fields may be deduced....
Vittorio De Falco
(University of Basel)
16/12/2015, 16:35
Talk
In this talk I consider the light path of observed photons emitted by matter in a *Schwarzschild gravitational field*. *Ray-tracing methods* are employed to tackle this problem and the used main equations are: **light bending**, **time delay** and **solid angle**. They are expressed through *elliptic integrals* that can be resolved numerically through generally complex routines. To run faster...
Prof.
Zoltan Haiman
(Columbia University)
16/12/2015, 16:35
In this talk, I will discuss possible characteristics of
electromagnetic (EM) emission from supermassive black hole (SMBH)
binaries. In particular, any detectable EM emission is likely to be
time-variable, and contain unique spectral signatures, which should
aid identifying SMHB binaries. I will discuss recent hydrodynamical
simulations, which suggest quasiperiodic modulations in the...
Mariele Motta
(University of Geneva)
16/12/2015, 16:35
In this talk I will discuss linear perturbations of dRGT massive bi-gravity with a single metric coupled to matter. First, I will introduce the formal derivation of the second order action for generic metrics. I will then use this result to identify stability bounds. Finally, I will discuss the linear perturbations on a FRW background, the cosmology of different branches, the number of degrees...
Dr
Francesco Miniati
(ETHZ - ETH Zurich)
16/12/2015, 16:35
Massive galaxy clusters (GC) are filled with a hot, turbulent and magnetised
intra-cluster medium (ICM). They are still forming under the action of gravitational instability driving supersonic accretion flows, which partially dissipate into heat through a
complex network of large scale shocks, while partly excite giant turbulent
eddies and cascade. Amongst others turbulence amplifies...
Karri Koljonen
(New York University Abu Dhabi)
16/12/2015, 16:36
Talk
Accreting black holes are responsible for producing the fastest, most powerful outflows of matter in the Universe. The formation process of powerful jets close to black holes is poorly understood, and the conditions leading to jet formation are currently hotly debated. In this talk I will present recent results that show empirical correlation between the properties of the plasma close to the...
Emmanuel Moulin
(CEA Saclay)
16/12/2015, 16:40
Talk
The Cherenkov Telescope Array (CTA) is a worldwide project aiming at building the next ground based gamma-ray observatory with a sensitivity ten times better than current experiments like H.E.S.S., MAGIC and VERITAS. CTA will be composed of several tens of telescopes with different sizes distributed on two sites located in the northern and southern hemispheres. CTA will also have a much wider...
Matthieu Heller
(Universite de Geneve (CH))
16/12/2015, 16:40
Talk
The SST-1M telescope is one of the prototypes under construction proposed to be part of the future Cherenkov Telescope Array.
It uses a standard Davis-Cotton design for the optics and telescope structure, with a dish diameter of 4 meters and a large field-of-view of 9 degrees.
An innovative camera with Silicon Photomultipliers and fully digital readout and trigger electronics, DigiCam, has...
Dr
Alessandro Papitto
(Space Science Institute Barcelona (ICE) CSIC-IEEC)
16/12/2015, 16:45
Talk
Neutron stars in low mass X-ray binaries can be spun-up to millisecond rotational periods by accreting the matter transferred by a companion star. When the rate of mass transfer decreases at the end of this Gyr-long X-ray bright phase, a radio pulsar powered by the rotation of the neutron star magnetic field turns on. Recently, the evolutionary link between these two classes of sources was...
Prof.
Isao Okamoto
(National Astronomical Observatory of Japan)
16/12/2015, 16:55
Talk
Making use of $3+1$ formulation of black hole electrodynamics, it is argued that the frame-dragging effect combines with unipolar induction, to sustain the double-structured magnetosphere consisting of the outer and inner domains, and high-energy activities therein. The emf's, $\cal{E}_{\rm out}$ and $\cal{E}_{\rm in}$, of a pair of unipolar induction batteries driving electric currents in the...
Pietro Guarato
(Université de Genève)
16/12/2015, 16:55
In this talk, a detailed analysis of the evolution of tensor perturbations in a cosmological background for a model of Hassan-Rosen theory of bigravity is presented. It is shown that gravitational waves are unstable in this setting, but also that in practice the amplitude of tensor perturbations generated during inflation is sufficiently suppressed to avoid this instability from showing up...
Guenter Sigl
(II. Institut für theoretische Physik, Universität Hamburg)
16/12/2015, 16:55
We will present work on the chiral magnetic instability in the context of hot neutron stars and its possible role for magneto genesis in the early Universe. Whether a chiral asymmetry in the electron sector, induced for example by the electroweak interaction, leads to growing helical magnetic fields depends on many factors that will be discussed in this talk.
Prof.
Andres Escala
(Universidad de Chile)
16/12/2015, 16:55
We study numerically the fate of SMBHs in galaxy mergers. If the galaxies involved in these mergers have a gas fraction of at least %1 is expected that a massive gaseous disk with a mass of ten to hundred times the mass of the SMBHs will be formed in the central kilo parsec of the merger remnant. The SMBHs in these nuclear region will form a SMBH binary which separation will shrink mainly due...
Dr
Roberto Soria
(ICRAR-Curtin University)
16/12/2015, 16:56
Talk
Determining the power output and efficiency of accreting black holes is a fundamental astrophysical problem:
we want to know the relation between mass accretion rate, radiative output (photons) and mechanical output
(kinetic energy of jets and winds). We focus in particular on off-nuclear black holes that are accreting
from a donor star at a rate near or above the critical Eddington...
Dr
Saverio Lombardi
(OAR-INAF, ASDC)
16/12/2015, 17:00
Talk
In the framework of the international Cherenkov Telescope Array (CTA) observatory, the Italian National Institute for Astrophysics (INAF) is developing the ASTRI SST-2M end-to-end prototype, installed at Mt. Etna (Italy) on September 2014, and is leading, in collaboration with Universities from Brazil and South Africa, the ASTRI mini-array composed of nine ASTRI small-sized, dual-mirror...
Hamish Clark
(University of Sydney)
16/12/2015, 17:05
Talk
In this talk I will discuss recent efforts to detect dark matter 'ultracompact minihalos' (UCMHs), including a novel utilisation of gravitational time-delay lensing with pulsars. Recently proposed as a type of small-scale dark matter structure, UCMHs are formed from large overdensities in the very early Universe. They have been shown to be able to persist through to the present day, providing...
Carlo Ferrigno
(University of Geneva)
16/12/2015, 17:10
Talk
The pulsar IGR J18245$-$2452 was dubbed as transitional, after detection of X-ray accretion induced pulsations, during an outburst which interrupted radio, rotationally-powered emission. The source was observed at the peak of its X-ray flux using XMM-Newton twice for a total exposure of 90 ks. At odds with other accreting millisecond pulsars, its power spectrum is characterised by a strong...
Johannes Noller
(University of Oxford)
16/12/2015, 17:15
Galileons appear in the low-energy limit of several cosmologically motivated theories, e.g. Massive Gravity, Bigravity and DGP. Yet we are only just beginning to understand some of their features. I will discuss newly discovered dualities and enhanced symmetries for (subsets of) Galileons and how they are related to scalar-theories of gravity and Massive gravity/Bigravity in particular.
Ksenia Ptitsyna
(INR Moscow, MSU Moscow, ISDC Geneve)
16/12/2015, 17:15
Poster
We consider the possible existence and observational consequences of the so-called vacuum "gaps" in the SMBH force-free magnetospheres in RIAF type sources. The gaps are the sites with a lack of the volume charge density in comparison to the plasma-filled force-free regions of the magnetosphere. They are analogous to the gaps in the pulsars magnetospheres. In such gaps direct acceleration of...
Mark Hannam
(Cardiff University)
16/12/2015, 17:15
Modelling the inspiral, merger and ringdown of generic (i.e., precessing) black-hole binaries has long been a major challenge for theoretical gravitational-wave astronomy. I will present a simple picture of the underlying phenomenology of these systems, which has lead to a novel technique to produce accurate generic waveform models.
Dr
Pedro Luis Luque-Escamilla
(Universidad de Jaén)
16/12/2015, 17:17
Talk
Jets appear in Astrophysics in very different environments and scales across the Universe, and they seem to share common features in all cases. Their study can then help us to understand a widespread outflow mechanism. However, their large-scale dynamics remain hidden to observation along human time scales because they usually develop too slowly, either because of their large sizes (in active...
Prof.
Benjamin Koch
(Pontifica Universidad Catolica de Chile)
16/12/2015, 17:18
Poster
It is a well known effect that a rotating black hole can accelerate
spinless particles to in principle arbitrary energies.
Within the formalism of the Spinning Top it is investigated
to which extend the "corresponding" process is also possible:
*"Can spinning tops be accelerated by a non-rotating black hole?"*
It is found that this is indeed the case.
Markus Boettcher
(North-West University)
16/12/2015, 17:20
Talk
This talk reviews recent progress in our understanding of the multiwavelength spectral and polarization signatures of relativistic shocks in the relativistic jets of active galactic nuclei and gamma-ray bursts. Spectral signatures are based on a self-consistent coupling of Monte-Carlo simulations of diffusive shock acceleration with radiation-transfer simulations. Our results indicate that, in...
Kadri Yakut
(University of EGE),
ismail özbakır
16/12/2015, 17:21
Poster
In this study, accurate and detailed solution of the frame-dragging process has been presented with a newly deduced equation of motion. Numerical solutions show that the results obtained in this study are somewhat different than those results presented in Thirring (1918). Obtained results have been applied to various astrophysical mediums as case studies.
Dragan Hajdukovic
(Institute of Physics, Astrophysics and Cosmology (ME))
16/12/2015, 17:24
Poster
While it is neglected, Hawking radiation is model-dependent; it depends on our model of the quantum vacuum. It was recently suggested that what we call dark matter and dark energy can be explained as the local and global effects of the gravitational polarization of the quantum vacuum by the immersed Standard Model matter. This result appears as the consequence of the working hypothesis that...
Andrea Vittino
(Universita' di Torino and INFN Torino)
16/12/2015, 17:30
Talk
Antideuterons can be produced through the nuclear coalescence of the antiprotons and the antineutrons that are originated in a dark matter pair annihilation or decay event. At low kinetic energies, the fluxes of these bound states are found to dominate over the astrophysical background and thus antideuterons may be considered as a very promising channel for a dark matter indirect detection,...
Dr
Kyle Parfrey
(Lawrence Berkeley National Laboratory)
16/12/2015, 17:30
Talk
The interaction of a rotating star's magnetic field with a surrounding plasma disc lies at the heart of many questions posed by neutron stars in X-ray binaries. I will present global simulations of this interaction, performed in the force-free (high-magnetization) limit of relativistic MHD, showing the opening of magnetic field lines, the formation and reconnection of magnetospheric current...
Massimiliano Rinaldi
(University of Trento)
16/12/2015, 17:35
Recently Kallosh, Linde, and collaborators have provided a unified description of single-field inflation in terms of just one parameter α. These so-called α-attractors predict a spectral index n_s and a tensor-to-scalar ratio r, which are fully compatible with the latest Planck data. The only common feature of all α-attractors is a non-canonical kinetic term with a pole, and a potential...
amruta jaodand
(ASTRON- Netherlands Institute for Radio Astronomy)
16/12/2015, 17:50
Talk
Recently, Bogdanov $\&$ Halpern (2015) identified the unassociated Fermi gamma-ray source $3$FGL~J$1544.6-1125$ as only the $4$th known "transitional millisecond pulsar" (tMSP), a claim further bolstered by follow-up observations by Bogdanov (2015). The tMSPs are a newly discovered class of binary systems that transition between states as a radio millisecond pulsar and a low-mass X-ray binary...
Mathieu Boudaud
(LAPTh Annecy France)
16/12/2015, 17:50
Talk
Using the updated proton and helium fluxes just released by the AMS-02 experiment we reevaluate the secondary astrophysical positron and antiproton fluxes. We compare our results with the positron flux and the preliminary antiproton to proton ratio, both measured by AMS-02. The main uncertainties for the theoretical calculation are assessed. For positrons, we test the possibility to explain...
Kenta Hotokezaka
(Hebrew University)
16/12/2015, 17:55
Measuring the neutron-star equation of state with gravitational waves is one of the scientific goal of grand-based gravitational-wave laser interferometers. To achieve this, we need end-to-end waveforms of binary neutron star mergers. Here we present waveforms that are computed with a long-term numerical relativity simulation. Then the waveforms are compared with those computed with effective...
Dr
Ilia Musco
(Laboratoire Univers et Théories (LUTH) - Observatoire de Paris)
16/12/2015, 17:55
It has been suggested that a scalar field φ non-minimally coupled to matter could be responsible for the observed accelerated expansion of the Universe. However, the fact that we are able to measure its effect only on cosmological scales but not on local ones, such as that of our solar system, might be the consequence of a screening mechanism. This is the essence of the Chameleon model....
Mr
Dimitrios Millas
(KU LEUVEN)
16/12/2015, 17:59
Talk
Several observations of astrophysical jets show evidence of a structure in the direction perpendicular to the jet axis, leading to the development of “spine & sheath” models of jets.
Two-component jets have been already examined (e.g. Meliani & Keppens 2007, Meliani & Keppens 2009) for relativistic hydrodynamic jets and relativistic magnetized jets with poloidal magnetic field. These...
Dr
Zorawar Wadiasingh
(Centre for Space Research, North-West University)
16/12/2015, 18:05
Talk
Searches of unidentified Fermi sources have vastly expanded the number of known galactic-field “black widow” and “redback” circular MSP binary systems. We model the high-energy emission from these systems due to relativistic leptons in the pulsar wind and those accelerated in intrabinary shocks. We show that the observed radio eclipses of the MSP can constrain the shock and system geometry....
Michael Kachelriess
(NTNU)
16/12/2015, 18:10
Talk
I review the results of a new calculation for the antiproton production by cosmic ray protons and nuclei and discuss the expected theoretical uncertainty. Then I discuss the antiproton flux expected from a local, 2 Myr old SN and the implication for indirect dark matter searches.
Haakon Andresen
(Max Planck Institut für Astrophysik)
16/12/2015, 18:15
To this day the exact nature of the detonation mechanise in core collapse supernovae reminds somewhat of a mystery. While numerical models are becoming more and more sophisticated, observations of the inner engine remain elusive. Because he core surrounded by dens stellar matter, electromagnetic radiation can only provide indirect information. Neutrinos and gravitational waves on the other...
Dr
Luigi Foschini
(National Institute for Astrophysics - INAF)
16/12/2015, 18:19
Poster
How powerful relativistic jets are generated is still one of the most important topics of the modern astrophysics. One of the most interesting and adopted theories was developed by Blandford and Znajek in 1977 with reference to jets from black holes. In the present work, I would like to draw the attention on some relatively unexplored features of the theory, with particular reference to the...
Ms
Marilyn Cruces
(Instituto de Astrofísica, Pontificia Universidad Católica de Chile)
16/12/2015, 18:20
Talk
Millisecond pulsars (MSPs) are old and very fast rotating neutron stars (NS) with much weaker magnetic fields than the younger classical pulsars and magnetars. Most MSPs are in binary systems, suggesting a "recycling scenario", in which a classical pulsar accretes matter from its companion and as a consequence spins up. Although this scenario explains the fast rotation, it is not clear yet how...
Dr
Alla Miroshnichenko
(Institute of Radio Astronomy, NAS of Ukraine)
16/12/2015, 18:22
Poster
We consider four samples of steep-spectrum radio sources from our catalogue UTR-2 at the decameter band. These contain galaxies and quasars of both spectral types - with linear steep spectrum and break steep spectrum. To obtain the relation of low-frequency luminosity, at the frequency 25 MHz, L_25 and linear size R of sample objects we determine one at the different redshift ranges at the...
Bhawna Gomber
(University of Wisconsin (US))
16/12/2015, 18:30
Poster
LZ is a second-generation dark-matter experiment designed to achieve unprecedented sensitivity to weakly interacting massive particles (WIMPs) of masses from a few GeV/c to hundreds of TeV/c2. With total liquid xenon mass of about 10 tonnes, LZ is planned to achieve a sensitivity to WIMP-nucleon spin-independent cross section approaching ∼2⋅10−48 cm2 in 3 years of operation. This represents an...
Hyerim Noh
(Korea Astronomy and Space Science Institute)
16/12/2015, 18:33
Poster
We show that the axion as a coherently oscillating scalar field acts as a cold dark matter (CDM) to the second-order perturbations in all cosmological scales including the super-horizon scale. The proof is made in the axion-comoving gauge. For a canonical mass, the axion pressure term causes deviation from the CDM only on scales smaller than the Solar System size. Beyond such a small scale the...
Ms
Marilyn Cruces
(Instituto de Astrofísica, Pontificia Universidad Católica de Chile)
16/12/2015, 18:35
Poster
The XMM-Newton space telescope is capable of 30-microsecond time resolution but its onboard clock drifts, for example due to changes in temperature. Current calibration documentation only provides an upper limit on the clock drift of 10^-8, but observations of X-ray millisecond pulsars (MSPs) suggest that it should be more stable.
Using kilo-second XMM-Newton observations of MSPs taken...
Dr
Saverio Lombardi
(OAR-INAF, ASDC)
16/12/2015, 18:36
Poster
Nowadays there are compelling evidences at several astrophysical scales for a large (~85%), dark, non-baryonic and non-relativistic component of the matter density of the Universe. The quest to explain the nature of Dark Matter (DM) represents a paramount issue of modern fundamental physics and astrophysics. The non-baryonic DM is compatible with a gas of cold and weakly interacting massive...
Dragan Hajdukovic
(Institute of Physics, Astrophysics and Cosmology (ME))
16/12/2015, 18:39
Poster
We show that if quantum vacuum fluctuations are virtual gravitational dipoles, then the phenomena usually attributed to hypothetical dark matter, may be considered as a consequence of the gravitational polarization of the quantum vacuum by the immersed baryonic matter; apparently, at least mathematically, the galactic halo of dark matter can be replaced by the halo of the polarized quantum...
Sinziana Paduroiu
(University of Geneva)
16/12/2015, 18:42
Poster
Using cosmological simulations we explore the effects of warm dark matter (WDM) particles (e.g. sterile neutrinos)on the structure formation for different mass particles. Properties like the velocity dispersion and the damping of the fluctuation spectrum imprint a distinct signature on the structure formation mechanism as well as on the evolution of structures and on the internal structure of...
Prof.
Francis Halzen
(IceCube/WIPAC)
17/12/2015, 09:00
Talk
The IceCube project has transformed one cubic kilometer of natural Antarctic ice into a neutrino detector. The instrument detects more than 100,000 neutrinos per year in the GeV to PeV energy range. Among those, we have recently isolated a flux of high-energy cosmic neutrinos. I will discuss the instrument, the analysis of the data, and the significance of the discovery of cosmic neutrinos....
Prof.
Jim Hinton
(Max Planck Institute for Nuclear Physics)
17/12/2015, 09:35
Talk
The last decade has marked a renaissance in the field of gamma-ray
astronomy. Results from space and ground-based instruments, in
particular Fermi and the big three of ground-based gamma-ray
astronomy: HESS, VERITAS and MAGIC, have transformed our view of the
gamma-ray sky. The current datasets allow the very detailed study of
archetypal particle accelerators across a very wide energy...
Prof.
Pasquale Blasi
(INAF)
17/12/2015, 10:10
Talk
I will summarize the current understanding of the physical processes responsible for cosmic ray acceleration, mainly in supernova remnant shocks, and their transport in the interstellar medium. Special attention will be devoted to the comparison with most recent data of both multifrequency emission from astrophysical sources and spectra of CRs measured locally.
Prof.
Virginia Trimble
(University of California Irvine)
17/12/2015, 11:20
Astrophysics, both the name and the subject, was born in the halcyon days of irrational international exuberance near the end of the 19th century, when there were 100's of international conferences in a decade and 10's of new international organizations being established. Those included the French-inspired Carte du Ciel and G.E. Hale's International Union for Solar Reseasch. General...
Prof.
Virginia Trimble
(University of California Irvine)
17/12/2015, 11:40
Nanda Rea
(University of Amsterdam/CSIC-IEEC)
17/12/2015, 11:50
Magnetars are a small subset of the neutron star population, being the strongest magnets we know of. They show themselves via powerful X/gamma-ray steady and flaring emission. The energetics of such flares in our Galaxy second only the supernova explosions. In this talk I will first review the observational characteristics of these highly magnetic pulsars, and some recent discoveries in the...
Sylvain Guiriec
(NASA Goddard Space Flight Center / UMD / CRESST)
17/12/2015, 12:10
The Gamma Ray Bursts (GRBs) are the most intense explosions in the universe and the footprints of stellar-mass black hole formation. Their initial phase, called prompt emission, lasts from a few ms to several tens of s. We suggest here to replace the historical spectral model (Band function) for the GRB prompt emission (keV-MeV energy regime) with a new one. We show that the complex GRB...
Dr
Maria Petropoulou
(Purdue University)
17/12/2015, 14:00
Talk
Blazars, being highly variable sources across the electromagnetic spectrum, may serve as promising targets for high-energy neutrino detection, especially during periods of flaring activity. Using as a testbed the nearby blazar Mrk 421, we present a detailed hadronic model of its emission during a 13-day flare in 2010 with unprecedented multi-wavelength and temporal coverage. We calculate the...
Mr
Ian Christie
(Purdue University)
17/12/2015, 14:00
A recent method has been proposed for probing the properties of the accretion disk surrounding Sgr A* located at our galactic center. This is based on a study of the collision between the disk fluid and the wind of the star, S2. We expand upon the previous work by constructing a semi-analytical model for the shock formation in the stellar wind. This takes into account the thermal pressure of...
Hiromi Saida
(Daido University)
17/12/2015, 14:00
According to the general relativity (GR), the black hole (BH) is characterized by three parameters: mass $M$, spin angular momentum $J$ and electric charge $Q$.
In real cases, the charge is expected to be zero, $Q=0$.
Then, the "BH observation" may be understood as the measurement of $M$ and $J$ through a direct observation of GR phenomena, for example the strong gravitational lens effect....
Masaru Shibata
(Kyoto University)
17/12/2015, 14:00
The merger of binary neutron stars is one of the most promising gravitational wave sources. For the detection of gravitational waves, numerical relativists are required to accurately predict gravitational waveforms and possible electromagnetic signals. I will talk on our latests effort for the numerical-relativity simulations: magnetohydrodynamics and radiation hydrodynamics simulations.
Emilia Järvelä
(Aalto University Metsähovi Radio Observatory)
17/12/2015, 14:00
Talk
The presence of powerful relativistic jets in narrow-line Seyfert 1 galaxies (NLS1) was confirmed when Fermi detected gamma-rays from a handful of them. In the current active galactic nuclei (AGN) paradigm powerful relativistic jets are produced only in massive elliptical galaxies with supermassive black holes, but NLS1 galaxies challenge this scenario since they have lower black hole masses,...
Jeroen Franse
(Leiden University)
17/12/2015, 14:00
Talk
The latest observational status of the candidate dark matter decay signal at 3.5 keV will be presented. This unidentified X-ray line is observed in multiple galaxies and galaxy clusters. Instrumental effects or plasma emission are disfavoured while the observations are consistent with a decaying dark matter interpretation. In addition to a review of the existing work, the latest developments...
Michael Daniel
(University of Liverpool)
17/12/2015, 14:00
As an observatory for ground-based gamma-ray astronomy in the energy region from a few tens of GeV to a few hundred TeV, the Cherenkov Telescope Array (CTA) will be the major next generation facility of Imaging Atmospheric Cherenkov Telescopes. The broad energy coverage will be accompanied by an order of magnitude improvement in flux sensitivity in the TeV region along with factor 2-5...
Davide Gerosa
(University of Cambridge)
17/12/2015, 14:20
We unveil a new dynamical instability in binary black holes with aligned spins. If the spin of the more massive black hole is aligned with the orbital angular momentum while the spin of the less massive black hole is anti-aligned, spins suddenly start to precess when the binary separation falls below the threshold of our newly discovered instability. This instability provides a natural...
Marco Berton
(University of Padova - Department of Physics and Astronomy "G. Galilei")
17/12/2015, 14:20
Talk
Narrow-line Seyfert 1 galaxies (NLS1s) are active galactic nuclei (AGN) recently identified as a new class of $\gamma$-ray sources. The high energy emission is explained with the presence of a relativistic jet observed at small angles, just like in the two classes of blazars. When the latters are observed at larger angles they appear as radio-galaxies, but an analogue parent population for...
R. Benton Metcalf
(Univerity of Bologna)
17/12/2015, 14:21
The Euclid mission is expected to discover perhaps two orders of magnitude
more strong gravitational lenses than are known today. These will be quasar-galaxy,
galaxy-galaxy and galaxy-cluster lenses. I will discuss what is required to find and
process such a large number of lenses. I will then describe what can be learned from
these lenses with respect to the dark matter...
David Richard Harvey
(EPFL - EPF Lausanne)
17/12/2015, 14:21
Talk
Recent studies into the dynamics of galaxy clusters and galaxy cluster members have revealed potential signatures of self-interacting dark matter. In this talk I will discuss the current evidence that supports this hypothesis and the observational signals that self-interacting dark matter may manifest itself as. I will finish by presenting current work and observations from the worlds best...
Vincent Tatischeff
(CSNSM, CNRS)
17/12/2015, 14:24
e-ASTROGAM is a gamma-ray observatory to be proposed as a Medium-size mission for the ESA science program. It is dedicated to the observation of the Universe with unprecedented sensitivity in the energy range 0.3 – 100 MeV extending up to GeV energies, together with a ground-breaking polarization capability. In this energy window, a variety of phenomena and sources await their discovery and...
Zhuo Li
(Peking University)
17/12/2015, 14:25
Talk
The origin of IceCube detected diffuse neutrinos is still unknown. Searching for their sources also helps to solve the problem of the cosmic ray orgigin. We assume that there is connection between the neutrino and gamma-ray fluxes from the sources. It holds if both the neutrinos and gamma-rays are haronic origin. Moreover, it should also hold in statistic sense even if the gamma-rays are...
Dr
Luigi Foschini
(National Institute for Astrophysics - INAF)
17/12/2015, 14:40
Talk
We studied a sample of 42 radio loud narrow-1ine Seyfert 1 galaxies (RLNLS1s) by using all the available multiwavelength observations and the information in literature. The masses of the central black holes are in the range $\sim 10^{6-8}M_{\odot}$, smaller than blazars, while the accretion luminosities span from $\sim 0.01$ to $\sim 0.49L_{{\rm Edd}}$, with an outlier at $0.003$, similarly to...
Elena Orlando
(Stanford University)
17/12/2015, 14:42
Diffuse emission has dramatically increased the interest of the astrophysical community, due to recent detailed observations by Planck, Fermi-LAT, H.E.S.S. and VERITAS. Unfortunately disentangling and characterizing this diffuse emission strongly depends on uncertainties in the knowledge of unresolved sources, cosmic rays, matter, radiation fields, and magnetic fields.
We discuss here the...
Mr
Takumu Kawamura
(University of Trento)
17/12/2015, 14:42
In this talk I will present some general relativistic magnetohydrodynamic simulations produced with the numerical code WHISKY. We have simulated magnetized binary neutron star mergers with two different Equations of State: ideal-fluid and H4. We have focused in particular on high-mass systems (both equal and unequal-mass ones) that produce after the merger a spinning black hole surrounded by a...
Thomas David Jacques
(Universite de Geneve (CH))
17/12/2015, 14:42
Talk
WIMPs with suppressed interactions can present observational challenges at lowest order. We study Majorana DM interacting via an axial-vector Z’, where both the self-annihilation rate and WIMP-nucleon scattering rate are suppressed. By including loop diagrams in the calculation of the self-annihilation rate, we find that the self-annihilation rate is notably enhanced relative to the tree-level...
Dr
Zuzanna Kostrzewa-Rutkowska
17/12/2015, 14:42
We present the results of our search for gravitationally lensed quasars in the OGLE survey. We show candidates from a 650 square degrees area behind the Magellanic Clouds System. The study of strong lensing time delays serves as a powerful probe in cosmology. The OGLE database provides long time light curves, allowing for a cost-effective way to accurately derive time delays and therefore...
Prof.
J S Yadav
(Tata Institute of Fundamental Reaserch)
17/12/2015, 14:43
ASTROSAT is India's first science satellite dedicated to multiwavelength astronomy. It has five science payloads which will cover UV to hard X-ray in low earth orbit. LAXPC instrument is one of the major instruments (415 kg payload weight and above 100 electronic cards). This instrument is designed and developed at TIFR and all the three LAXPC flight units have successfully completed...
Joseph Avenoso
(The College of New Jersey),
Tyler Viducic
(The College of New Jersey)
17/12/2015, 15:00
Poster
It has been previously shown that the energy lost from an incident gravitational wave (GW) on a cloud of charged particles can manifest itself an electromagnetic field, causing the GW to attenuate. Furthermore, it can be shown that the presence of the field and the circumstances in which it was generated leads to currents and subsequently magnetic fields. We plan to calculate how much energy...
Antonis Manousakis,
Bhupendra Mishra
(Nicolaus Copernicus Astronomical Center Warsaw Poland),
Frederic Vincent
(Observatoire de Paris)
17/12/2015, 15:00
Poster
We simulate a purely hydrodynamical torus with constant specific angular momentum around a Schwarzschild black hole. The goal is to search for quasi-periodic oscillations (QPOs) of the torus. Initial torus setup is subjected to radial, vertical and a diagonal (combination of radial and vertical) velocity perturbations. The hydrodynamical simulations are performed using the general relativistic...
Mikhail Ivanov
(Ecole Polytechnique Federale de Lausanne (CH))
17/12/2015, 15:03
Talk
Baryon acoustic oscillations (BAO) provide us with one of the most powerful cosmological probes. However, the BAO are plagued by non-linear effects which must be taken into account. I will discuss these effects and their physical impact on correlation functions in real and momentum spaces. I will present a new technique (so-called 'IR — resummation') to account for these effects to all orders...
Frederic Vincent
(Observatoire de Paris)
17/12/2015, 15:03
Poster
Quasi-periodic oscillations (QPO) are an important probe of the timing properties of black-hole binaries and a ubiquitous feature of their PDS. For that reason, many attempts to explain their origin have also reduced them to their frequencies. In order to explore their behavior beyond this, we consider three simple classes of models: elongated hot spots, tori and spirals. We perturb the...
Wolfgang Kastaun
(Trento University)
17/12/2015, 15:03
A large number of publications model hyper-massive neutron stars (i.e. neutron stars with total mass exceeding the maximum allowed for a uniformly rotating star) produced in binary neutron star mergers by assuming a rotation profile with a rapidly rotating core. We confront such models with results of general relativistic hydrodynamic simulations which exhibit a slowly rotating core instead....
Dr
Oleg Titov
(Geoscience Australia)
17/12/2015, 15:03
Poster
Some models of the expanding Universe predict that the astrometric proper motion of distant radio sources embedded in space-time are non-zero as radial distance from observer to the source grows. Systematic proper motion effects would produce a predictable quadrupole pattern on the sky that could be detected using Very Long Baseline Interferometry (VLBI) technique. This quadrupole pattern...
Dr
Daniele VIVOLO
(INFN Napoli)
17/12/2015, 15:05
Talk
The ANTARES experiment has been running in its final configuration since 2008. It is the largest
neutrino telescope in the Northern hemisphere. After the discovery of a cosmic neutrino diffuse flux
by the IceCube detector, the search for its origin has become a key mission in high-energy
astrophysics. Particularly interesting is the indication (although not significant with the...
Rebecca Nealon
(Monash University)
17/12/2015, 15:06
Poster
Observations of QPOs from neutron stars and black holes suggest they must be a feature of the accretion disc surrounding these objects. Their measured frequencies indicate they are from the inner disc, where effects from the Lense-Thirring precession are significant. However, because the properties of the high and low frequency QPOs are so different, it is thought that separate physical...
Dr
Paolo Soffitta
(IAPS/INAF)
17/12/2015, 15:06
XIPE, the X-ray Imaging Polarimetry Explorer, is one of the three missions selected by ESA for study phase for down-selection of the fourth medium size mission. XIPE will measure the polarization in hundreds of celestial sources of different classes. It will allow for answering, in a novel way, to questions related to the acceleration phenomena in PWNe, Supernovae and blazars, to the transport...
Charalampos Markakis
(University of Southampton)
17/12/2015, 15:24
Gravitational waves from neutron-star and black-hole binaries carry valuable information on their physical properties and probe physics inaccessible to the laboratory. Neutron stars can be well-modelled as simple barotropic fluids during the part of binary inspiral most relevant to gravitational wave astronomy, but the crucial geometric and mathematical consequences of this simplification have...
Mr
Yuuki Omori
(McGill University)
17/12/2015, 15:24
Large scale structure in the universe causes gravitational lensing of
the cosmic microwave background (CMB), which has now been
well-measured by several CMB experiments. By cross-correlating CMB
lensing with tracers of large scale structure (like galaxies), it is
possible to obtain new constraints on cosmology and a better
understanding of possible systematic errors in cosmological...
Dr
Adam Amara
(ETHZ - ETH Zurich)
17/12/2015, 15:24
Talk
The Dark Energy Survey (DES) is a 5000 square degree survey targeting dark matter and dark energy science. This year sees the release of the first science results from the DES collaboration using data taken during science verification. I plan to present these new results, which include dark matter maps, cosmology constraints and new discoveries such as the new strong lens systems being found....
Denys Malyshev
(University of Geneva)
17/12/2015, 15:24
The Galactic centre (GC) is a bright gamma-ray source with the GeV-TeV band spectrum composed of two distinct components in the 1-10 GeV and 1-10 TeV energy ranges. The nature of these two components is not clearly understood. We present imaging, spectral, and timing analysis of data from ~7 years of observations of the Galactic centre by FERMI/LAT gamma-ray telescope complemented by sub-MeV...
Sergio Petrera
(University of L'Aquila)
17/12/2015, 15:25
Talk
The Pierre Auger Observatory studies the most energetic cosmic rays arriving at Earth, in the energy range from 10^17 eV up to 10^20 eV and beyond. More than 10 years data taking have led to major advances in our knowledge of the origin and nature of cosmic rays. We present a summary of the latest results, discussing the challenges on the astrophysical interpretation of the flux suppression...
Dr
Jan-Willem den Herder
(SRON)
17/12/2015, 15:25
The Athena mission is the second large mission of ESA with an expected launch date of 2028. The data will be gathered by a very large mirror (2 m2) with a 5 arcsec resolution. Athena will have two instruments: the Wide Field Imager combines a large field of view (40 x 40 arcmin2) with Si-class energy resolution and the X-ray Integral Field Unit (X-IFU) which enables high spectral resolution...
Alejandro Cruz Osorio
(Universidad Nacional Autónoma de México)
17/12/2015, 16:15
We present CAFE, a code designed to solve the equations of relativistic ideal magnetohydrodynamics (RMHD) in three cartesian dimensions. We present the standard tests for the relativistic RMHD regime. The tests include among the two-dimensional (2D) and 3D tests with magnetic field. The code uses high-resolution shock-capturing methods, and we present the error analysis for a combination that...
Dmitriy Chernyshov
(Lebedev's Institute of Physics, Moscow, Russia)
17/12/2015, 16:15
Fermi bubbles are giant gamma-ray structures seen above and below the Galactic plane with characteristic size of order of 10 kpc. They also show very good correlation with the microwave emission discovered by the WMAP telescope and the residual diffuse emission in the range above 30 GHz found by the Planck satellite. Correlation between gamma-ray emission observed by Fermi and radio emission...
Dr
Stefan Oslowski
(Bielefeld University / MPIfR Bonn)
17/12/2015, 16:15
Gravitational waves are expected to be radiated by supermassive black hole binaries formed during galaxy mergers. A stochastic superposition of gravitational waves from all such binary systems will modulate the arrival times of pulses from radio pulsars. Using observations of millisecond pulsars obtained with the Parkes radio telescope, we constrain the characteristic amplitude of this...
Matteo Bugli
(Max Planck Institute for Astrophysics)
17/12/2015, 16:15
Talk
Accretion on compact objects is commonly considered the most plausible mechanism to power up a list of astrophysical systems (such as AGNs, GRBs, X-Ray Binaries, etc. . . ) and in particular magnetic fields are believed to play a major role in enabling the accretion process through the development of magnetic instabilities. We investigated the effects of a finite resistivity in a magnetized...
Antonio Surdo
(INFN - Lecce (IT))
17/12/2015, 16:15
Talk
The CR spectrum has been studied by the ARGO-YBJ experiment in a wide energy range (TeVs→ PeVs) . This study is particularly interesting because not only it allows a better understanding of the so called ’knee’ of the energy spectrum and of its origin, but also provides a powerful cross-check among very different experimental techniques.
The unique detector features (full coverage, time...
Stefan Gillessen
(Max Planck Inst fur Extraterrestrische Physik)
17/12/2015, 16:15
Located at 8kpc only, the Galactic Center allows studying a galactic nucleus in unparalleled detail.
With the advent of high-resolution, near-infrared instrumentation in the last decade it became
possible to follow individual stellar orbits around the radio source Sgr A* with orbital periods
as short as 12 years. The orbits determine the mass of Sgr A* to 4 million solar masses,
and thus...
Dr
Dominique Eckert
(University of Geneva)
17/12/2015, 16:15
In the local Universe, about half of the total baryon content of the Universe is still escaping our census. Understanding the state and distribution of these missing baryons is a major question for our knowledge of galaxy evolution and cosmology. Numerical simulations predict that the missing baryons should be in the form of a very diffuse, warm-hot (T~1e5-1e7 K) state, which would remain...
Prof.
Bence Kocsis
(Eötvös University)
17/12/2015, 16:35
The Fermi satellite has recently detected gamma ray emission from the central regions of our Galaxy. This may be evidence for dark matter particles, a major component of the standard cosmological model, annihilating to produce high-energy photons. We show that the observed signal may instead be generated by millisecond pulsars that formed in dense star clusters in the Galactic halo. Most of...
Dr
William East
(Stanford University)
17/12/2015, 16:35
A period of exponential expansion early in our cosmic history is usually
invoked to explain the large scale homogeneity and isotropy of the Universe.
However, there remain important questions about the conditions under which
inflation can actually start when homogeneity is not assumed to begin with it.
In this talk, I will present results from fully general-relativistic simulations used to...
Prof.
Sergei Klioner
(Lohrmann Observatorium, Technische Universitaet Dresden)
17/12/2015, 16:35
Esa's second space astrometry mission Gaia was launched in December 2013 and after an extended commissioning period started its scientific operations in July 2014. After 17 months of observations Gaia delivered an immense dataset of high-accuracy positional observations. In spite of some unexpected difficulties with the instrument, Gaia Data Processing and Analysis Consortium is progressing...
Jörg Paul Rachen
(IMAPP / Radboud University Nijmegen)
17/12/2015, 16:35
Talk
It seems to be a striking coincidence that all putative cosmic ray
sources which are dynamically able to fill the universe with the observed
extragalactic cosmic ray density can produce the same maximum confinement
energy, eBR ~ 10^20 eV, while being spread in scale R over 10 orders of
magnitude - the most impressive representation of this coincidence is the famous
Hillas plot, in which...
Bhupendra Mishra
(Nicolaus Copernicus Astronomical Center Warsaw Poland)
17/12/2015, 16:36
Talk
The stability of geometrically thin radiation pressure dominated accretion disks around black holes remained under debate. Analytical work concludes that such disks should be thermally unstable. Newtonian shearing box simulations in the past show that these disks may be thermally stable. In last few years other pseudo-Newtonian shearing box simulations showed that the disks are thermally...
Thomas Baumgarte
(Bowdoin College)
17/12/2015, 16:55
We study critical phenomena in the gravitational collapse of a radiation fluid. We perform numerical simulations in both spherical symmetry and axisymmetry, and observe critical scaling in both supercritical evolutions, which lead to the formation of a black hole, and subcritical evolutions, in which case the fluid disperses to infinity and leaves behind flat space. We identify the critical...
Vitalii Sliusar
(Astronomical Observatory of Taras Shevchenko National University of Kyiv, Ukraine)
17/12/2015, 16:55
We study effects due to a possible presence of putative dark matter mini-halos (DM clumps) in the light curves of source images of the extragalactic gravitational lens systems. The extended clumps are described by means of a simplified model of the lens mapping. Every microlens consists of a central point mass surrounded by a concentric extended mini-halo; this is characterized by the ratio q...
Dr
Frederic Vincent
(Observatoire de Paris)
17/12/2015, 16:55
Near-future sub-millimetric VLBI observations of the surroundings of the Galactic center supermassive black hole, Sgr A*, by the Event Horizon Telescope (EHT) will lead to unprecedented constraints on the nature of the accretion flow surrounding this compact object. One of the most fascinating goal of the EHT is to test the presence of an event horizon by imaging the *black hole shadow*, and...
yoann genolini
(LAPTh)
17/12/2015, 16:55
Talk
PAMELA and, more recently, AMS-02, are ushering us into a new era of greatly reduced statistical uncertainties in experimental measurements of cosmic ray fluxes. In particular, new determinations of traditional diagnostic tools such as the boron to carbon ratio (B/C) are expected to significantly reduce errors on cosmic-ray diffusion parameters, with important implications for astroparticle...
Anna Chashkina
(Tuorla Observatory, University of Turku)
17/12/2015, 16:57
Talk
One of the ultraluminous X-ray sources M82 X-2 was recently identified as a neutron star accreting at a rate significantly larger that ordinary X-ray pulsars. The accretion disc outside the magnetosphere probably still remains below the local Eddington limit but its structure may be affected by the radiation of the central source (accretion column) that together with magnetic torques shifts...
Dr
Antoine Lassus
(Max Planck Institute für Radioastronomie)
17/12/2015, 16:57
We have searched for continuous gravitational wave (CGW) signals produced by individually resolvable, circular supermassive black hole binaries (SMBHBs) in the latest EPTA dataset, which consists of ultra-precise timing data on 41 millisecond pulsars. Several algorithms have been used and depending on the adopted detection algorithm, the 95% upper limit on the sky-averaged strain amplitude...
Michael Kachelriess
(NTNU)
17/12/2015, 17:15
Talk
I review the escape model for Galactic cosmic rays (CRs) that reproduce over a wide range of energies all available experimental data for individual groups of CR nuclei.
Then I discuss how the extragalactic proton component derived within this model can be explained by astrophysical sources, especially blazars. The diffuse neutrino and γ-ray fluxes produced by these CR protons interacting...
Manuel David Morales
(Instituto de Física y Matemáticas - Universidad Michoacana de San Nicolás de Hidalgo)
17/12/2015, 17:15
I present the numerical evolution of a self-gravitating massless spherical scalar field based on a new code which implements the 3+1 tetrad formulation of general relativity on compactified constant mean curvature (CMC) hypersurfaces developed by Bardeen, Sarbach and Buchman. The major advantage of this formulation is that it allow us to model with high accuracy the scalar radiation at future...
Dr
Robert Braun
(SKA Organisation, Jodrell Bank Observatory)
17/12/2015, 17:15
The SKA is now in the detailed design phase with construction scheduled to
begin in early 2018, followed by early science from about 2020. A major
component of its broad-ranging science program is focused on addressing
questions in fundamental physics. The current status of the project will
be summarised and the prospects for advancing relativistic astrophysics
will be highlighted.
Pavel Abolmasov
(University of Turku)
17/12/2015, 17:18
Talk
Using general relativistic analytical treatment in Kerr metric and numerical simulations with the public HARM2D code, we consider the vertical structure and velocity field in the inner parts of a black hole accretion disk, both outside and inside the last stable orbit.
Chaotic magnetic fields frozen into the accreting matter easily become the dominant pressure source inside the sonic point...
Dr
Lindley Lentati
(Cambridge University)
17/12/2015, 17:19
The European Pulsar Timing Array (EPTA) was established in 2006 as a collaboration between European research institutes and radio observatories. The key mission of the EPTA is the direct detection of nanohertz gravitational waves (GWs) using the high-precision timing of an ensemble of millisecond pulsars. The primary source of GWs in the nanohertz band is expected to be merging supermassive...
Ingyin Zaw
(NYU Abu Dhabi)
17/12/2015, 17:35
Poster
Studies discerning whether there is a significant correlation between ultra high energy cosmic ray (UHECR) arrival directions and optical AGN are hampered by the lack of a uniformly selected and complete all-sky optical AGN catalog. To remedy this, we are preparing such a catalog based on the 2MASS Redshift Survey (2MRS), a spectroscopic sample of $\sim 44,500$ galaxies complete to a K...
Mrs
Daniela Perez
(Instituto Argentino de Radioastronomia)
17/12/2015, 17:35
We show that a spherically symmetric gravitational collapse of a star can result in a bounce if the equation of state behaves with sufficient rigidity just before the formation of an event horizon. The relativistic time dilation produced by the strong gravity makes the whole process to be undistinguishable from a black hole on timescales shorter than the Hubble time for a distant observer. We...
Mr
Markus Rexroth
(EPFL - EPF Lausanne)
17/12/2015, 17:35
Poster
Flexion is the second order weak gravitational lensing effect which is responsible for the arclike appearance of lensed sources. Its strong signal in the intermediate regime and the orthogonality to the weak lensing shear field make flexion an ideal complement to today's gravitational lensing measurements. Furthermore, its high sensitivity to local density peaks makes it a great tool for...
Prof.
Benjamin Brown
(Marquette University)
17/12/2015, 17:35
Positron annihilation at 511 keV coming from the direction of the Galactic Center could be occurring in a variety of different ways. One channel, in-flignt annihilation, occurs by charge exchange approximately below 100 eV as positrons slow by inelastic collisions from keV energies. The characteristic Doppler broadened line width and shape is of interest in comparing to galactic gamma ray data...
Dr
Kuo Liu
(Max-Planck-Institute for Radio Astronomy)
17/12/2015, 17:35
Searching for gravitational waves has nowadays been a vital astrophysical experiment in gravity and pulsar timing array (PTA) constitutes the major effort in low frequency regime. The detection of gravitational waves with PTAs relies on the technique of high precision pulsar timing currently achieved with the 100-m class radio telescopes. In this talk, I will present an overview of the Large...
Mr
Shohei Saga
(Naogya university)
17/12/2015, 17:38
Poster
Vector mode of cosmological perturbation theory imprints characteristic signals on the weak lensing signals such as curl- and B-modes which are never imprinted by the scalar mode.
However, the vector mode is neglected in the standard first-order cosmological perturbation theory since it only has a decaying mode.
This situation changes if the cosmological perturbation theory is expanded up to...
Zakaria Meliani
(LUTH, Observatoire de Paris)
17/12/2015, 17:38
Talk
Accretion disks play an important role in the evolution of their relativistic inner compact objects. The emergence of a new generation of interferometers will allow resolving these accretion disks and providing more information about the properties of the central gravitating object. Due to this instrumental leap forward it is crucial to investigate the accretion disk physics near various types...
Dr
Zuzanna Kostrzewa-Rutkowska
(Warsaw University Astronomical Observatory)
17/12/2015, 17:41
Poster
Most stellar remnants so far have been found in binary systems where they interact with matter from their companion. Isolated neutron stars and black holes are hard to find as they do not emit light, yet they are predicted to be present in our Galaxy in vast numbers.
We explored the OGLE-III database of 150 million objects observed in years 2001-2009 and found 59 microlensing events...
Dr
Alberto Sesana
(University of Birmingham)
17/12/2015, 17:41
Pulsar timing arrays (PTAs) are dramatically improving their sensitivity. Current upper limits start to be in tension with vanilla models of gravitational wave driven, circular supermassive black hole binaries (SMBHBs), although nothing can be safely ruled out yet. I will discuss how we can use current and future PTA limits to investigate the nature of SMBHBs and learn about their overall...
Dr
Ilia Musco
(Laboratoire Univers et Théories (LUTH) - Observatoire de Paris)
17/12/2015, 17:55
In the context of gravitational collapse to form a black hole, one sees the appearance of inner and outer trapping horizons (foliated by marginally trapped surfaces), as was already noted in numerical calculations in the 1960s. This phenomenology has acquired new interest in connection with discussions of the Hayward unified first law of black hole dynamics. We have investigated the nature of...
Viacheslav Zhuravlev
17/12/2015, 17:59
Talk
This work is related to one of the major unsolved problems in the theory of accretion disks:
the problem of pure hydrodynamical origin of effective viscosity in their interiors.
If it were solved, we would have a general alternative to the well-known conception of
supercritical turbulence excited by magneto-rotational instability. As has been widely discussed by fluid physicists since...
Dr
Sotiris Sanidas
(University of Amsterdam)
17/12/2015, 18:03
Pulsar Timing Arrays observe a set of millisecond pulsars at high timing precision over long periods of time, aiming to directly detect gravitational waves. Probing the nHz frequency regime, PTAs are sensitive also to many primordial GW sources, with one of them being cosmic strings; a web of string-like energy concentrations that may have formed right after Inflation and permeates the...
Alberto Saa
(UNICAMP)
17/12/2015, 18:15
Poster
By exploring the numerical scheme introduce in [1], we analyze the asymptotic ($u\to\infty$) evolution of Robinson-Trautman spacetimes, with special emphasis on the behavior of the apparent horizon and its curvature anisotropies, which can indeed induce accelerations and a recoil in the remnant black hole due to asymmetrical emission of gravitational waves [2].
**References**
[1] A. Saa...
259.
The High Energy cosmic-Radiation Detection (HERD) Facility onboard China's Future Space Station
Ming Xu
(Chinese Academy of Sciences (CN))
17/12/2015, 18:15
The High Energy cosmic-Radiation Detection (HERD) facility is one of several space astronomy payloads onboard China's future Space Station, which is planned for operation starting around 2020. It is designed as a next generation space facility focused on indirect dark matter search, precise cosmic ray spectrum and composition measurements up to the knee energy, and high energy gamma-ray...
Mikhail Belyaev
(UC Berkeley/TAC)
17/12/2015, 18:19
Talk
Accretion is a ubiquitous process in astrophysics. In cases when the magnetic field is not too strong and a disk is formed, accretion can proceed through the mid plane all the way to the surface of the central compact object. Unless that compact object is a black hole, a boundary layer will be formed where the accretion disk touches its surfaces. The boundary layer is both dynamically and...
Dragan Hajdukovic
(Institute of Physics, Astrophysics and Cosmology (ME))
17/12/2015, 18:25
The unrivalled advantage of tiny trans-Neptunian binaries is that they are the best available realisation of an isolated two body system with very weak external and internal Newtonian gravitational field. As a consequence, in many cases (as for instance in the case of the binary (55637) 2002 UX25), the known Newtonian precession of orbit of the satellite is so small that cannot be detected by...
Mariusz Dabrowski
(University of Szczecin)
17/12/2015, 18:35
In this talk I will briefly present the advantages and drawbacks of varying speed of light c cosmologies and relate them to the of varying fine structure constant α theories. Then, I will discuss some new tests (redshift drift and angular diameter distance maximum against Hubble function) which may allow measuring timely and possibly even spatial change of the speed of light. The criteria to...
Dr
Antonio Stamerra
(INAF-Osservatorio Astrofisico di Torino, Italy)
17/12/2015, 18:39
Poster
We report on the results of a multifrequency campaign on the BL Lac object PG 1553+113 that was organized by the Whole Earth Blazar Telescope (WEBT) Collaboration in 2013 April-August. Nineteen optical, two near-IR, and three radio telescopes monitored the source to follow its behaviour at low energies during and around the high-energy observations by the MAGIC telescopes in April-July. A...
Ms
Lis Sulistiyowati
(Institut Teknologi Bandung)
17/12/2015, 18:42
Poster
In this study, we report the examinations of the spectra of ULXs in two nearby (< 10 Mpc) pairs of interacting galaxies M51 and NGC 4485/90 collected by Swift-XRT observations from 2005 to 2014 and 2008 to 2015 for each target, respectively. We consider 9 ULXs in M51 and 5 ULXs in NGC 4485/90. We obtain 116 ObsIDs of M51 and 37 ObsIDs of NGC 4485/90. For each pair of interacting galaxy, there...
Prof.
Stefano Vitale
(University of Trento)
18/12/2015, 09:00
Talk
The talk will likely take place during the cruise of LISA Pathfinder to its final interplanetary orbit. LISA Pathfinder is the technology precursor of the Gravitational Wave (GW) observatory that ESA intends to launch as their 3rd large size mission within the current planning.
The talk will review the status and the scientific objectives of the GW observatory, and of its reference mission...
Prof.
Mustapha Ishak
(The University of Texas at Dallas)
18/12/2015, 09:35
Talk
There are over 1300 known exact solutions to Einstein’s equations. Part of these solutions found applications in astrophysics including the solar system, compact objects, and cosmology. These have offered some physical or mathematical insights into the systems under consideration. In this review talk, some characterizing notions about exact solutions will be outlined along with some examples....
Prof.
Luigi Stella
(INAF - Osservatorio Astronomico di Roma)
18/12/2015, 10:10
Talk
High-time-resolution and spectroscopic observations of accreting collapsed objects in the X-ray range provide access to strong-field gravity, through measurements of the motions of matter orbiting a few gravitational radii away from black holes. Key predictions of strong field general relativity, such as relativistic epicyclic motions, precession, light bending and the presence and radius of...
Prof.
Andrew Fabian
(University of Cambridge)
18/12/2015, 11:20
Talk
The innermost region of the accretion flow around X-ray bright, unobscured, Active Galactic and Black Hole Binaries (AGN and BHB) is being routinely mapped by X-ray spectral-timing of the reflection spectrum produced by irradiation of the accretion disc. The spin of the black hole can be determined by identifying the inner edge of the reflection region with the ISCO. The black hole in many of...
Alexander Tchekhovskoy
(Uiversity of California Berkeley)
18/12/2015, 11:55
Talk
After reviewing the physics of jet formation by accreting black holes, I will present the results of recent 3D general relativistic magnetized fluid dynamics simulations and discuss the insights they give us into the disk-jet connection. I will finish by presenting the simulated spectra and images and the constraints on the near event horizon physics coming from the comparison to the...
Felipe Garrido Goicovic
(Instituto de Astrofisica, PUC, Chile)
Poster
There is compelling evidence that most -if not all- galaxies harbour a super-massive black hole (SMBH) at their nucleus, hence binaries of these massive objects are an inevitable product of the hierarchical evolution of structures in the universe, and represent an important but thus-far elusive phase of galaxy evolution. Gas accretion via a circumbinary disc is thought to be important for the...
Paul de Fromont
(Observatoire de Paris - LUTH)
Poster
In this work I show that we can reconstruct the large scale density profiles surrounding extrema in the density field such as Dark Matter Halos or Cosmic Voids (their exact symmetric in the initial conditions).
I show that those profiles can be parametrized in such a way that they conserve some inner properties in their evolution whatever the underlying dynamics. Using N-body simulations of...
Prof.
Shouhong Wang
(Indiana University)
Poster
We shall present a blackhole theorem and a theorem on the structure of our Universe, proved in a recently published paper, based on 1) the Einstein general theory of relativity, and 2) the cosmological principle that the universe is homogeneous and isotropic. These two theorems are rigorously proved using astrophysical dynamical models coupling fluid dynamics and general relativity based on a...
Dr
Dnyaneshwar Pawar
(School of Mathematical Science,Swami Ramanand Teerth Marathwada University, Nanded, 431606 (India))
Poster
Abstract
The present paper deals with cylindrically symmetric metric in
the form of Marder (1958) with Saez-Ballester theory of gravitation
in the presence of perfect
fluid and dark energy. In order to obtain
the deterministic solution of the field equations we have assumed that
the expansion scalar in the model is proportional to the Eigen value
of the shear tensor. We have also...
