Conveners
Gamma-Ray Astrophysics: Extragalactic
- Stefano Gabici (APC)
- mahaya ()
- Stefan Funk (Universität Erlangen)
- Daniel Mazin (ICRR)
Gamma-Ray Astrophysics: Extragalactic
- Stefano Gabici (APC)
- mahaya ()
- Daniel Mazin (ICRR)
Gamma-Ray Astrophysics: GRBs and experiments
- Stefan Funk (Universität Erlangen)
- Stefano Gabici (APC)
- mahaya ()
- Daniel Mazin (ICRR)
Gamma-Ray Astrophysics: Diffuse emission, Galactic Center and CR propagation
- Stefano Gabici (APC)
- mahaya ()
- Daniel Mazin (ICRR)
Gamma-Ray Astrophysics: Galactic
- Stefan Funk (Universität Erlangen)
- Stefano Gabici (APC)
- mahaya ()
- Daniel Mazin (ICRR)
Gamma-Ray Astrophysics: Galactic Sources and Future missions
- Stefan Funk (Universität Erlangen)
- Stefano Gabici (APC)
- mahaya ()
- Daniel Mazin (ICRR)
Prof.
Kohta Murase
(Penn State University)
26/10/2015, 14:00
Gamma-ray Astrophysics
Oral presentation
Active galactic nuclei, including blazars, have been considered as cosmic-ray source candidates, and GeV-TeV gamma rays can be used as a powerful probe. I will discuss signatures of secondary gamma rays and their multi-messenger connection.
Dr
Robert Wagner
(University of Stockholm)
26/10/2015, 14:25
Gamma-ray Astrophysics
Oral presentation
By upgrading the H.E.S.S. array of Imaging Atmospheric Cherenkov Telescopes with a fifth, 28-m diameter telescope, the sensitivity of H.E.S.S. towards low gamma-ray energies has been extended to energies below 100 GeV. This allows studies particularly of distant Active Galactic Nuclei (AGN) with soft gamma-ray spectra. Results of observations with the five-telescope array will be discussed,...
Prof.
Dijana Dominis Prester
(University of Rijeka / The University of Tokyo)
26/10/2015, 14:45
Gamma-ray Astrophysics
Oral presentation
The blazar QSO B0218+357 is the most distant AGN (z=0.944) detected so far in the TeV range. It is gravitationally lensed by the galaxy B0218+357G (z=0.68). Very-high-energy (VHE) gamma-ray emission from QSO B0218+357 was detected in July 2014 with the MAGIC telescopes, by measuring the time-delayed image of the flare, detected earlier by FERMI in the GeV range. Its emission enables the study...
Dr
Ievgen Vovk
(Max Planck Institute for Physics)
26/10/2015, 15:00
Gamma-ray Astrophysics
Oral presentation
The blazars high-energy emission is believed to be produced in the jets, powered by their central supermassive black holes. At the same time the location of the emission region within the jet is presently uncertain - mainly due to its extremely small angular size, far beyond the capabilities of the existing gamma-ray instruments. However, in the rare case of the gravitationally lensed blazars,...
Mr
Miguel Nievas-Rosillo
(Universidad Complutense de Madrid, Grupo de Altas Energías)
26/10/2015, 15:15
Gamma-ray Astrophysics
Oral presentation
Very-high-energy (VHE, E > 100 GeV) gamma-ray emission from the very distant flat spectrum radio quasar PKS 1441+25 (z = 0.940) was detected in April 2015 with the MAGIC telescopes. Aside from the gravitationally lensed VHE blazar QSO B0218+357 (z = 0.944), also detected by MAGIC, PKS 1441+25 is the most distant VHE blazar detected to date. The VHE detection occurred in April 2015 during...
Dr
Susumu Inoue
(RIKEN)
26/10/2015, 15:30
Gamma-ray Astrophysics
Oral presentation
X-ray observations of active galactic nuclei (AGN) are revealing the widespread existence of powerful, baryonic outflows reaching mildly relativistic velocities, seen as variable, blue-shifted absorption lines of ionized heavy elements, in both radio-quiet and radio-loud objects. Sometimes called ultra-fast outflows (UFOs), they are plausibly interpreted as winds driven by the accretion disk...
Dr
Katsuaki Asano
26/10/2015, 15:45
Gamma-ray Astrophysics
Oral presentation
Multi-wavelength observations of blazars have revealed curved feature in photon spectrum. Moreover, in some cases, the required electron spectral index at injection becomes harder than 2. In order to reproduce such a curved electron spectrum, we discuss the second order Fermi acceleration by turbulence in the jet. Here, we focus on the time-dependent effects of the electron acceleration and...
Dr
Alberto Dominguez
(Clemson University/UC Madrid)
26/10/2015, 16:30
Gamma-ray Astrophysics
Oral presentation
The Fermi Large Area Telescope (LAT) has been routinely gathering science data since August 2008, surveying the full sky every three hours. The first Fermi-LAT catalog of sources detected above 10 GeV (1FHL) relied on three years of data to characterize the >10 GeV sky. The improved acceptance and point-spread function of the new Pass 8 event reconstruction and classification together with six...
Dr
Abelardo Moralejo Olaizola
(Institut de Físca d'Altes Energies, Barcelona)
26/10/2015, 16:55
Gamma-ray Astrophysics
Oral presentation
1ES 1011+496 is a blazar located at a redshift z=0.212, revealed as a very-high-energy gamma-ray emitter by the MAGIC telescopes in 2007. In February 2014 the source underwent an unprecedented flaring episode, reaching a peak flux of almost 14 times the flux measured at the time of discovery, before returning to its low state. The MAGIC telescopes observed the source for a total of 17 nights...
Dr
Fabian Schüssler
(CEA-Saclay / Irfu)
26/10/2015, 17:13
Gamma-ray Astrophysics
Oral presentation
When very high-energy photons (VHE, E>100 GeV) propagate over cosmological distances, they interact with background light by pair production. Observations of spectral features in the VHE band of extragalactic sources related to this energy-dependent absorption process with the H.E.S.S. array of Cherenkov telescopes allow measuring the spectral energy distribution (SED) of the extragalactic...
Dr
Maxim Barkov
(ABBL RIKEN)
26/10/2015, 17:28
Gamma-ray Astrophysics
Oral presentation
We propose a model to explain the ultra-bright GeV gamma-ray flares observed from the blazar 3C454.3. The model is based on the concept of a relativistic jet interacting with compact gas condensations produced when a star (red giant) crosses the jet close to the central black hole. The study includes an analytical treatment of the evolution of the envelop lost by the star within the jet, and...
Mr
Francesco Borracci
(Max Planck Institute for Physics (MAGIC Telescopes))
26/10/2015, 17:43
Gamma-ray Astrophysics
Oral presentation
The blazar Mrk 421 is one of the closest and brightest extragalactic very high energy (VHE, >100 GeV) gamma-ray emitters, and hence one of the VHE objects that we can study best. Since 2009, Mrk 421 is yearly observed during 6 months with more than 25 instruments in the framework of broadband multifrequency campaigns. During April 2013, Mrk421 underwent unprecedented flaring activity in many...
Dr
Marlene Doert
(Ruhr-Universität Bochum)
26/10/2015, 17:58
Gamma-ray Astrophysics
Oral presentation
We present recent results on the high-frequency-peaked BL Lac object Markarian 501 derived from extensive multi-wavelength campaigns in the years 2009, 2012 and 2013. The blazar is located in our extragalactic neighborhood (z=0.034), which reduces spectral uncertainties due to absorption effects of the Extragalactic Background Light and allows for significant detections on sub-hour timescales,...
Ms
Tanya Edwards
(Max-Planck-Institut für Kernphysik)
26/10/2015, 18:13
Gamma-ray Astrophysics
Oral presentation
Ground-based gamma-ray astronomy is still tackling a major problem: background. Reconstruction techniques exist to distinguish most of the background of hadrons but an irreducible background of electrons and gamma-like protons still remain. I present here a new technique making use of direct Cherenkov light and air shower development that provides a way to efficiently distinguish between...
Dr
Saverio Lombardi
(OAR-INAF, ASDC)
26/10/2015, 18:28
Gamma-ray Astrophysics
Oral presentation
In the framework of the international Cherenkov Telescope Array (CTA) observatory, the Italian National Institute for Astrophysics (INAF) has developed a large field-of-view (9.6 degrees), dual-mirror, small-sized, end-to-end telescope (ASTRI SST-2M). This prototype has been installed at Mt. Etna (Italy) on September 2014, and it is currently undergoing engineering tests. Soon after the...
Dr
Valerie Connaughton
(USRA)
27/10/2015, 14:00
Gamma-ray Astrophysics
Oral presentation
Our understanding of high-energy emission from Gamma-Ray Bursts has greatly advanced with observations from the Fermi gamma-ray space telescope. I will review the Fermi observations, with particular emphasis on the surprising detection of both prompt and temporally extended emission at high energies. I will also discuss the prospects for detection of GRBs with the High Altitude Water...
Dr
Roberta ZAnin
(MPIK-Heidelberg)
27/10/2015, 14:25
Gamma-ray Astrophysics
Oral presentation
Pulsars and their synchrotron nebulae have been extensively observed in the gamma-ray energy band only in the last 10 years. With the advent of the Fermi satellite the number of known gamma-ray emitting pulsars has increased by one order of magnitude, touching the 150 mark. On the other hand, the last generation of imaging Cherenkov telescopes proved that the pulsar wind nebulae are the most...
Julian Sitarek
(University of Lodz)
27/10/2015, 14:50
Gamma-ray Astrophysics
Oral presentation
MAGIC (Major Atmospheric Gamma Imaging Cherenkov) is a
system of two imaging atmospheric Cherenkov telescopes located at the
Canary island of La Palma. The telescopes are performing observations
of gamma rays with energies between 50 GeV and tens of TeV. In 2014
MAGIC celebrated its 10th anniversary of scientific operations. In
this talk I will present the recent highlights of the...
Nahee Park
(University of Chicago)
27/10/2015, 15:13
Gamma-ray Astrophysics
Oral presentation
VERITAS is an array of four imaging atmospheric Cherenkov telescopes designed to observe gamma-ray emission from astrophysical objects in the energy range from 85 GeV to > 30 TeV. Located at the Fred Lawrence Whipple Observatory in Arizona, VERITAS has operated successfully over seven years with two major upgrades that improved the performance of the array. The scientific goals of VERITAS...
Dr
Aion Viana
(Max-Planck-Institut für Kernphysik (MPIK))
27/10/2015, 15:36
Gamma-ray Astrophysics
Oral presentation
H.E.S.S. is an array of Imaging Atmospheric Cherenkov Telescopes observing the gamma-ray sky beyond ~20 GeV. In the course of the first 10 years of operation, this experiment significantly contributed to the field of ground-based gamma-ray astronomy. In 2012, a fifth telescope was added at the centre of the original array. This large telescope of 28 meters diameter improves the performance of...
Dr
Rolf Buehler
(DESY,)
27/10/2015, 16:30
Gamma-ray Astrophysics
Oral presentation
Gamma-rays give us a view on the acceleration some of the most energetic particles in the universe. These particles are usually thought to be accelerated in (relativistic) shocks. However, with the advances in Particle In Cell simulations over the past years it became clear that magnetic reconnection is also a compelling alternative. In this talk, I will discuss what gamma-ray observations can...
Dr
Carmelo Evoli
(GSSI, L'Aquila)
27/10/2015, 16:55
Gamma-ray Astrophysics
Oral presentation
DRAGON is a public software package developed to study CR propagation in the Galaxy.
It includes diffusive/advective transport, as well as reacceleration and energy losses, for most of the nuclear and lepton species. Each species can originate from astrophysical sources (e.g., SNR, Pulsars) or from DM annihilations/decays in the halo, making the code very suitable both for studying Galactic...
Dr
Daniele Gaggero
(SISSA)
27/10/2015, 17:20
Gamma-ray Astrophysics
Oral presentation
The Fermi-LAT measurements of the diffuse Galactic gamma-ray emission reveal a hardening of the cosmic-ray (CR) spectrum with decreasing Galactocentric radius. This result can be the signature of different CR trasport properties in the inner Galaxy, and in particular a harder rigidity scaling of the diffusion coefficient.
We model this effect with DRAGON and we provide a good description of...
Prof.
Soebur Razzaque
(University of Johannesburg)
27/10/2015, 17:35
Gamma-ray Astrophysics
Oral presentation
The Fermi bubbles at the Galactic center have been imaged in sub-TeV gamma rays by the Fermi-Large Area Telescope and might have been detected in 0.3-1 PeV neutrinos by the IceCube Neutrino Observatory. A hadronic model, involving cosmic-ray interactions in the bubble volumes, can account for both gamma-ray and neutrino observations but is far from being confirmed due to low neutrino...
Dr
Francesca Calore
(University of Amsterdam)
27/10/2015, 17:50
Gamma-ray Astrophysics
Oral presentation
A spatially extended excess of gamma rays collected by the Fermi-LAT from the inner region of the Milky Way has been discovered by different groups and with increasingly sophisticated techniques of data analysis. I will review the characterization of spectral and morphological properties of the excess when variations of the Galactic diffuse emission are properly taken into account. Recently,...
Dr
Ilya Gurwich
(NRCN & Weizmann Institute)
27/10/2015, 18:05
Gamma-ray Astrophysics
Oral presentation
We show that the Fermi Bubbles and the Galactic haze are naturally interpreted as inverse-Compton and synchrotron emission from the same spectrum of cooling cosmic ray electrons. This avoids the ad-hoc spectral features and superfluous acceleration mechanisms typically assumed. The model implies that the bubbles originated 2-3 Myr ago, the mean magnetic field in the haze region is ~3\muG, and...
70.
The very high energy gamma-ray diffuse emission in the Galactic Center region as seen by H.E.S.S
Dr
Anne Lemière
(APC, CNRS/Université Paris7, Paris France)
27/10/2015, 18:20
Gamma-ray Astrophysics
Oral presentation
The Very High Energy (VHE) emission from the Galactic Center Ridge was revealed by H.E.S.S. in 2006, after subtraction of the two bright point sources HESS J1745-290 possibly associated with Sgr A*, and HESS J1747-281 associated with the composite supernova remnant G0.9+0.1. The hard spectrum of the Ridge emission and its spatial correlation with the local gas density suggest that the emission...
Dr
Ryan Chaves
(CNRS Montpellier)
29/10/2015, 14:00
Gamma-ray Astrophysics
Oral presentation
H.E.S.S. is a hybrid array of five imaging atmospheric Cherenkov telescopes operating in the very-high-energy (VHE) gamma-ray energy range ~20 GeV to 100 TeV. With its unprecedented sensitivity, broad energy range, fast slew time, and Southern-hemisphere location in Namibia, H.E.S.S. provides an unparalleled, high-quality view of the VHE Galaxy, in a multi-messenger approach that builds on...
Bronislaw Rudak
(Nicolaus Copernicus Astronomical Center, Warsaw)
29/10/2015, 14:20
Gamma-ray Astrophysics
Oral presentation
The Vela pulsar (PSR J0835 − 4510) is the brightest persistent source in the high-energy γ-ray sky. It is a relatively near, young and energetic rotation-powered pulsar. Vela was a key target for the High Energy Stereoscopic System phase II array (H.E.S.S. II). Observations were carried out following a hint of pulsed emission above 20GeV seen using Fermi-LAT data. In this talk we present...
Dr
Christian Fruck
(Max-Planck-Institut für Physik, München)
29/10/2015, 14:35
Gamma-ray Astrophysics
Oral presentation
We present the results from the Major Atmospheric Gamma Imaging Cherenkov (MAGIC) telescope of the search for TeV variability in the very high energy (VHE) gamma ray regime performed in the years 2012-2015 during the pericenter passage of the G2 gas cloud. This gas cloud orbits the Galactic Center (GC) on a highly eccentric trajectory with a pericenter distance of only a few thousand...
Daniela Hadasch
29/10/2015, 14:50
Gamma-ray Astrophysics
Oral presentation
There are several types of Galactic sources that can potentially accelerate charged particles up to GeV and TeV energies. These accelerated particles can produce Very High Energy (VHE) gamma-ray emission through different processes, for example inverse Compton scattering of ambient photon fields by accelerated electrons.
We study various transient and variable stellar objects in the VHE...
Mr
Dmitriy Khangulyan
(Rikkyo University)
29/10/2015, 15:10
Gamma-ray Astrophysics
Oral presentation
Several compact binary systems appeared to have spectral energy
distributions that peak is gamma-ray energy band. Almost all these
sources have been detected in the high energy and very high energy
regimes with Fermi/LAT and ground based Cherenkov detectors,
respectively. Detection of very high energy photons from these compact
sources implies operation of a very efficient particle...
Dr
Shuta Tanaka
(ICRR, The University of Tokyo)
29/10/2015, 15:30
Gamma-ray Astrophysics
Oral presentation
Rotation-powered pulsars release their rotational energy as relativistic magnetized plasma and create pulsar wind nebulae (PWNe) around them.
Although magnetars are considered as magnetically powered pulsar, they also release their rotational energy by the wind.
This is obvious from the fact that they are spinning down.
We have been detected PWNe around energetic pulsars which have...
Dr
Fabian Schüssler
(CEA-Saclay / Irfu)
29/10/2015, 15:50
Gamma-ray Astrophysics
Oral presentation
In this contribution the H.E.S.S. programs to follow up on multi-wavelength and multi-messenger observations and alerts will be presented.
Ongoing activities searching for high-energy gamma-ray emission in coincidence with Gamma Ray Bursts, recent extensions to Fast Radio Bursts and (in the future) gravitational waves are going to be discussed. Furthermore the newly installed H.E.S.S....
Dr
Yasunobu Uchiyama
(Rikkyo University)
29/10/2015, 16:30
Gamma-ray Astrophysics
Oral presentation
Diffusive shock acceleration (DSA), a well-developed theory of the acceleration process at work in supernova remnants (SNRs), lays the foundation for the SNR paradigm of the CR origin, though key problems are yet to be solved. Determining the acceleration efficiency is one of the key issues, where the term “acceleration efficiency” carries two different meanings; one is related to the maximum...
Prof.
Yutaka Fujita
(Osaka University)
29/10/2015, 16:55
Gamma-ray Astrophysics
Oral presentation
Radiatively inefficient accretion flows (RIAFs) in low-luminosity active galactic nuclei (LLAGNs) have been suggested as cosmic-ray and neutrino sources, which may largely contribute to the observed diffuse neutrino intensity. We show that this scenario naturally predicts hadronic multi-TeV gamma-ray excesses around galactic centers. The protons accelerated in the RIAF in Sagittarius A* (Sgr...
Dr
Kunihito Ioka
(KEK)
29/10/2015, 17:15
Gamma-ray Astrophysics
Oral presentation
Recent analyses of Fermi Large Area Telescope data show an extended GeV γ-ray excess on top of the expected diffuse background in the Galactic center region, which can be explained by annihilating dark matter (DM) or a population of millisecond pulsars (MSPs). We propose observations of very high energy (VHE) γ-rays to distinguish the MSP scenario from the DM scenario. GeV γ-ray MSPs should...
Prof.
Wlodek Bednarek
(University of Lodz)
29/10/2015, 17:35
Gamma-ray Astrophysics
Oral presentation
We discuss scenarios which turn to production of gamma-ray emission
within the redback type binary systems containing millisecond pulsar
and a low mass stellar companion. The millisecond pulsar can eject relativistic leptons from the inner magnetosphere in the rotation powered stage. These leptons, or after additional re-acceleration, can interact with radiation of companion star.
In the...
Prof.
Michael Burton
(University of New South Wales)
29/10/2015, 17:55
Gamma-ray Astrophysics
Oral presentation
The Mopra Southern Galactic Plane molecular gas survey is the next generation CO survey of the distribution and dynamics of the molecular gas along the southern galactic plane. Being conducted with 0.6 arcmin and 0.1 km/s resolution, it provides an order of magnitude improvement in both spatial and spectral resolution over the Dame et al 2001 survey, currently our standard source of reference...
Dr
Jeremy Perkins
(NASA/GSFC)
29/10/2015, 18:10
Gamma-ray Astrophysics
Oral presentation
The gamma-ray energy range from a few hundred keV to a few hundred MeV has remained largely unexplored, mainly due to the challenging nature of the measurements, since the pioneering but limited observations by COMPTEL on the Compton Gamma-Ray Observatory (1991-2000). This energy regime encompasses the transition between thermal and nonthermal processes, and accurate measurements are critical...
Prof.
Denis Bernard
(LLR, Ecole Polytechnique & CNRS/IN2P3.)
29/10/2015, 18:25
Gamma-ray Astrophysics
Oral presentation
gamma-ray astronomy suffers from the sensitivity gap between the
energy ranges for which Compton telescopes and pair telescopes are
efficient.
This blank part of the SED of the cosmic sources that are active at
high energy hinders the understanding of their nature. In particular
the pi0 bump that is dreamt to be signing the hadronic interactions in
the cosmic accelerators that produce...
Mr
Mitsunari Takahashi
(ICRR)
29/10/2015, 18:40
Gamma-ray Astrophysics
Oral presentation
Above tens of GeV, gamma-ray observations with the Fermi Large Area Telescope (LAT) are often dominated by statistical uncertainties due to the low source flux and the limited acceptance. The newly released Pass 8 analysis extended the acceptance of Fermi-LAT to ~ 2.5 m^2 sr over 100 GeV, and made effective an event class that can improve the acceptance at these very high gamma-ray energies:...
