12-20 July 2017
Asia/Seoul timezone
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GA(Gamma ray Astronomy)


Location: BEXCO
Date: from 13 Jul 13:30 to 20 Jul 12:30


  • 20 Jul 11:00 - 11:45 Ground
    • Park, Nahee
  • 20 Jul 11:45 - 12:30 Space
    • Perkins, Jeremy

Timetable | Contribution List

Displaying 120 contributions out of 120
on 20/7/2017 at 2:00
on 20/7/2017 at 2:45
We calculate the high energy gamma-ray emission expected during the periastron passage of the pulsar PSR J2032+4127 which form extended binary system with the massive companion star MT91 213. The gamma-ray emission is expected due to the comptonization of the stellar radiation by electrons accelerated at the pulsar wind and stellar wind collision shock. We apply the numerical code for the cascade ... More
Presented by Piotr BANASINSKI on 19/7/2017 at 5:45
GRB study is one of the main goals of the Lomonosov space mission. Multimessenger GRB observation is the only way of progress achievement in their study. The Lomonosov satellite is the first space mission in which the multi-wave length observations of GRBs are realized in real time without necessity of optical instrument re-orientation on GRB monitor trigger. The mission payload includes the GRB m ... More
Presented by Vitaly BOGOMOLOV on 18/7/2017 at 4:45
The η Carinae binary system hosts one of the most massive stars, which features the highest known mass-loss rate. This dense wind encounters the much faster wind expelled by its stellar companion, dissipating mechanical energy in the shock, where particles can be accelerated up to relativistic energies and subsequently produce very high energy γ-rays. We used data from the Fermi Large Area Teles ... More
Presented by Roland WALTER on 13/7/2017 at 5:45
The Fermi-LAT data accumulated over 7 years of gamma-ray observations, together with the high resolution gas (CO & HI) and the dust opacity maps, are used to study the emissivity of gamma-rays induced by interactions of cosmic rays (CRs) with the interstellar medium. Based on the dust opacity templates, the gamma-ray emissivity was measured for 36 segments of the Galactic plane. Furthermore, the g ... More
Presented by Ruizhi YANG on 18/7/2017 at 4:45
We will report on the Third Catalog of Hard Fermi-LAT Sources (3FHL) built from data taken with the Fermi Large Area Telescope (LAT). This catalog describes the gamma-ray sky at energies above 10 GeV relying on the first 7 years of LAT data using the Pass 8 event-level analysis. The 3FHL contains 1556 sources characterized in the 10 GeV--2 TeV energy range. The sensitivity and angular resolution a ... More
Presented by Alberto DOMINGUEZ
In order to provide an interpretation of X-ray and gamma-ray emission spectra of jets in Active Galactic Nuclei a detailed knowledge of particle acceleration at dissipation sites is required. In the case of blazars, the dissipation of jet energy may involve mildly relativistic magnetized internal shocks with Lorentz factor of γ ≤ 2. Of special interest for the emission modeling is the level of ... More
Presented by Arianna LIGORINI on 13/7/2017 at 9:00
The Cherenkov Telescope Array (CTA) will be the largest ground-based very-high-energy gamma-ray detection observatory in the world with more than one hundred telescopes located in two sites in the northern and southern hemispheres. The energy coverage, in the southern CTA array, will extend up to hundreds of TeV thanks to a large number (up to 70) of small size telescopes, with their primary mirro ... More
Presented by Maria Concetta MACCARONE on 14/7/2017 at 8:45
Supernova remnants are believed to be one of the major sources of Galactic cosmic rays. SNR CTB 37A is known to be interacting with several dense molecular clouds as traced by OH 1720 MHz maser. Radio and X-ray observations of the SNR confirm a mixed-morphology classification of the remnant. The TeV gamma ray source HESS J1714-385 is coincident with the SNR, though it’s still not clear whether t ... More
Presented by Soheila ABDOLLAHI on 17/7/2017 at 4:30
The polarization parameters of high energy photons from Gamma-Ray Bursts are thought to hold a wealth of information on the nature of these transient events. To date several GRB polarization measurements have been performed, including some by a dedicated instrument, however both the small number of measurements and a lack of precision has made it impossible to exclude any of the existing GRB emiss ... More
Presented by Merlin KOLE on 18/7/2017 at 5:00
We report on the detection of flaring activity from the prominent Fanaroff-Riley I radio galaxy NGC 1275 located in the Perseus cluster of galaxies in the very-high-energy gamma-ray band. The observations were performed with the MAGIC telescopes between 2016 and 2017 over several months. During this time period, the mean flux above 100 GeV was measured to be ten times brighter than during previous ... More
Presented by Dorit GLAWION on 13/7/2017 at 7:30
In this work we estimate the gamma-ray emission from hadronic interactions produced by cosmic rays (CR) accelerated in Galactic sources that remain confined around their sources for a time longer than the one estimated using the average Galactic diffusion coefficient. The confinement is due to magnetic turbulence that CRs self-produce during the escaping process in a region around the source where ... More
Presented by Giovanni MORLINO on 19/7/2017 at 5:00
Compact binary systems can provide us with unique information on astrophysical particle acceleration and cosmic ray production. However, only five binary systems have ever been observed in the regime of TeV gamma rays. The High Altitude Water Cherenkov (HAWC) Observatory has high uptime (duty cycle >95%) and a wide field of view (2 sr.), making it well-suited for observing transient sources such a ... More
Presented by Chang Dong RHO on 13/7/2017 at 8:30
Extragalactic jets are the largest particle accelerators in the universe, producing radiation ranging from radio wavelengths up to very high-energy gamma rays. Spatial origin of gamma-ray radiation from these sources cannot be fathom due to the poor angular resolution of the detectors. We propose to investigate gravitationally lensed blazars. Cosmic lenses magnify the emission and produce time del ... More
Presented by Anna BARNACKA on 19/7/2017 at 5:30
The Cherenkov Telescope Array is a next generation ground-based gamma-ray observatory designed to detect photons in the 0.02 to 300 TeV energy range. With a sensitivity improvement of one order of magnitude over currently operating facilities, coupled with significantly better angular resolution, the array will be used to address many open questions in high-energy astrophysics. In addition, CTA wi ... More
Presented by Roberta ZANIN on 15/7/2017 at 5:45
It is generally assumed that fluorescence radiation does not play a significant role in the performance of Cherenkov telescopes. This assumption is put to the test of detailed Monte Carlo simulations. To this end we have implemented the production and tracking of fluorescence radiation inside the CORSIKA code, and generated gamma-ray induced showers in the VHE energy range. The most accurate fluor ... More
Presented by Fernando ARQUEROS on 17/7/2017 at 8:00
A full scale 9.7m Schwarzschild-Couder Telescope (SCT) is a prototype for the Medium Size Telescopes (MSTs) of the Cherenkov Telescope Array (CTA). The SCT-MST has been proposed as an instrument capable to achieve the ultimate performance of the imaging atmospheric Cherenkov technique in the energy range from 100 GeV to 10 TeV in the CTA installation. The SCT employs an aplanatic two-mirror optica ... More
Presented by Vladimir VASSILIEV on 18/7/2017 at 5:45
We present a novel interpretation of the gamma-ray diffuse emission measured by H.E.S.S. in the Galactic Center (GC) and the Central Molecular Zone (CMZ) regions. We start with a data driven analysis based on PASS8 Fermi-LAT data which allows to extend down to few GeV the spectra measured by H.E.S.S. and to infer the primary Cosmic Ray (CR) radial distribution above 100 GeV. We compare those resul ... More
Presented by Dario GRASSO on 19/7/2017 at 7:30
Gamma ray detected high-redshift blazars (z>3) are intrinsically interesting since they inform us about the evolution of gamma-ray blazars and are, by definition, some of the more luminous blazars in the Universe. It has been found in many studies that such high z blazars host extremely massive black holes (M_BH> 1e9 M_sun) and thus shed a new light on the formation of supermassive black holes in ... More
Presented by Dario GASPARRINI on 13/7/2017 at 9:00
High-energy gamma rays of interstellar origin are produced by the interaction of cosmic-ray (CR) particles with the diffuse gas and radiation fields in the Galaxy. The main features of this emission are well-understood and are reproduced by existing CR propagation models employing 2D Galactocentric cylindrically symmetrical geometry. However, the high-quality data from instruments like the Fermi L ... More
Presented by Troy PORTER on 13/7/2017 at 4:30
MAGIC is a system of two Cherenkov telescopes designed to perform observations of gamma rays with energies from about 50 GeV to tens of TeV. A low energy threshold and an excellent low energy performance make it a powerful instrument for studies of high energy processes in active galactic nuclei. The MAGIC Collaboration dedicates about 40% of the telescopes' time to such observations, both monitor ... More
Presented by Julian SITAREK on 13/7/2017 at 4:45
PKS1510-089 is a flat spectrum radio quasar located at a redshift of 0.36. It is one of only a few such sources detected in very-high-energy (VHE, >100 GeV) gamma rays. Though PKS1510-089 is highly variable at GeV energies, until recently no variability has been observed in the VHE band. In 2015 May PKS1510-089 showed a high state in optical and in the GeV range. MAGIC observations performed at th ... More
Presented by Adrian BILAND on 13/7/2017 at 8:30
Gamma-ray observations of microquasars at high and very-high energies can provide valuable information of the acceleration processes inside the jets, the jet-environment interaction and the disk-jet coupling. Two high-mass microquasars have been deeply studied to shed light on these aspects: Cygnus X-1 and Cygnus X-3. Both systems display the canonical hard and soft X-ray spectral states of black ... More
Presented by Alba FERNANDEZ-BARRAL on 13/7/2017 at 8:15
PKS 1510-089 (z=0.361) is one of only a handful of flat spectrum radio quasars that have been detected at very high energy (VHE, E>100GeV) gamma-rays. It is a very active source across the entire electromagnetic spectrum. VHE observations in May 2016 with H.E.S.S. and MAGIC revealed an exceptionally strong flare, which lasted for less than two nights, and exhibited a peak flux of about 0.8 times t ... More
Presented by Michael ZACHARIAS on 13/7/2017 at 8:15
2HWC J1928+178 is a source recently discovered at TeV energies in the second HAWC catalog. It is coincident with the Fermi unidentified source 3FGL J1928+1739 and the pulsar PSR J1928+1746, which is 83 kyr old and located at a distance of 5 kpc with an Edot=1.6 x 10$^{36}$ erg/s. 2HWC J1928+178 is not detected by any of the IACTs currently in operation, which puts strong constrains on the morpholo ... More
Presented by Ruben LOPEZ-COTO on 15/7/2017 at 9:15
Observations of high-energy cosmic $gamma$-rays provide us with direct information of high-energy phenomena in the universe. Fermi-LAT is observing a $gamma$-ray sky and offering new insights. On the other hand, past and current observations have some limitations. Improvements in an angular resolution and polarization sensitivity are one of keys for a breakthrough of the limitations. We are develo ... More
Presented by Satoru TAKAHASHI on 14/7/2017 at 5:15
The Large Magellanic Cloud (LMC) is an irregular satellite galaxy of the Milky Way. The Fermi-LAT has recently discovered periodic GeV gamma-ray emission from a binary system in the LMC, LMC P3, with a period of ~10.3 days. The LMC has been observed extensively at Very-High-Energy (VHE) gamma-rays with the H.E.S.S. telescopes. Significant VHE gamma-ray emission has been detected from LMC P3, with ... More
Presented by Nukri KOMIN on 13/7/2017 at 8:00
Atmospheric monitoring is an integral part of the design of the Cherenkov Telescope Array (CTA), as atmospheric conditions affect the observations by Imaging Atmospheric Cherenkov Telescopes (IACT) in multiple ways. The variable optical properties of the atmosphere are a major contribution to the systematic uncertainty in the determination of the energy and flux of the gamma photons. Both the deve ... More
Presented by Jan EBR on 14/7/2017 at 9:00
A few Galactic objects are known to be variable sources of photons with energies above 100 GeV. These systems are mostly binaries, where variability can generally be connected to the orbital period, although particle acceleration and gamma-ray production processes are not well understood. We present here an overview of the VERITAS binary discovery program at VHE energies and a summary of eleven ye ... More
Presented by Gernot MAIER on 13/7/2017 at 7:30
We report on the VERITAS detection of very-high-energy (VHE, E> 100 GeV) gamma-ray emission from the optically bright quasar OJ 287 which is located at a redshift of z = 0.306. OJ 287 has been observed to display regular optical outbursts with a period of approximately 12 years, with the last major optical outburst having occurred in 2015. In order to explain this periodicity, models involving a b ... More
Presented by Stephan O'BRIEN on 13/7/2017 at 5:30
In June 2015, the Flat Spectrum Radio Quasar 3C 279 underwent an extremely bright gamma-ray flare, with an increase of the flux above 100 MeV by a factor 10 in less than 1 day, revealing an intrinsic variability timescale of 2 minutes as detected by the Fermi-LAT. We present results of target of opportunity observations with the H.E.S.S. experiment on this source over the nights around the peak of ... More
Presented by Carlo ROMOLI on 13/7/2017 at 7:45
The detections of fast TeV gamma-ray flares from blazars since the late 1990s have made substantial contributions to advance our understanding of these objects. These extreme flares have posed challenges to blazar models, and led to the development of new models (e.g. localized regions of magnetic reconnection, and plasma passing a standing shock). However, there are only a handful of such flares ... More
Presented by Qi FENG on 13/7/2017 at 8:45
The Water Cherenkov Detector Array (WCDA) is an important component of Large High Altitude Air Shower Observatory (LHAASO), which mainly aims at surveying the northern sky for VHE gamma ray sources. The WCDA has an area of 78,000 m2, and is sub-divided into 3,120 cells by black curtains, with a PMT deployed in each cell. Currently, the R&D is finished. In this talk, the basic design, performance a ... More
Presented by Mingjun CHEN on 14/7/2017 at 7:30
We report on the Fermi High-Latitude Extended Sources Catalog (FHES), a comprehensive search for spatially extended gamma-ray sources at high Galactic latitudes based on data from the Fermi Large Area Telescope (LAT). While the majority of high-latitude LAT sources are extragalactic blazars that appear point-like within the LAT angular resolution, there are several physics scenarios that predict t ... More
Presented by Matthew WOOD on 19/7/2017 at 5:15
Imaging Atmospheric Cherenkov Telescopes study the highest energy (up to tens of TeV) photon emission coming from nearby and distant astrophysical sources, thus providing valuable results from searches for Lorentz Invariance Violation (LIV) effects. Highly variable, energetic and distant sources such as Pulsars and AGNs are the best targets for the Time-of-Flight LIV studies. However, the limited ... More
Presented by Leyre NOGUÉS on 19/7/2017 at 4:30
Sub-milliarcsecond imaging of nearby main sequence stars and binary systems can provide critical information on stellar phenomena such as rotational deformation, accretion effects, and the universality of starspot (sunspot) cycles. Achieving this level of resolution in optical wavelength bands (U/V) requires use of a sparse array of interferometric telescopes with telescope baseline separations ex ... More
Presented by David KIEDA on 19/7/2017 at 9:00
The ALPACA (Andes Large area PArticle detector for Cosmic ray physics and Astronomy) experiment is aimed at observing cosmic gamma rays above 10 TeV in the southern sky with wide field of view and high sensitivity. We are planning to construct an 83,000 m^2 surface air-shower array and a 5,400 m^2 underground muon detector array, on a highland at the altitude of 4,740 m halfway up Mt. Chacaltaya o ... More
Presented by Munehiro OHNISHI on 17/7/2017 at 9:00
Recent high-energy missions have allowed keeping watch over blazars in flaring states, which provide deep insights into the engine powered by supermassive black holes. However, having a quasar caught in a very bright flaring state is not easy requiring long surveys. Therefore, the observation of such flaring events represents a goldmine for theoretical studies. Such a flaring event was captured by ... More
Presented by Eugenio BOTTACINI on 14/7/2017 at 4:30
VERITAS is one of the world’s most sensitive detectors of astrophysical VHE (E > 100 GeV) gamma rays. This array of four 12-m imaging atmospheric-Cherenkov telescopes has operated for ~10 years, and nearly 5000 hours of observations have been targeted on active galactic nuclei (AGN). These studies of blazars and radio galaxies have resulted in 36 detections. Most of these detections are accompan ... More
Presented by Wystan BENBOW on 13/7/2017 at 4:30
It is widely believed that Galactic Cosmic Rays (CR) are accelerated in Supernova Remnants (SNRs) through the process of diffusive shock acceleration. In this scenario, particles should be accelerated up to energies around 1 PeV (the so-called 'Knee') and emit gamma rays. To test this hypothesis, precise measurements of the gamma-ray spectra of young SNRs at TeV energies are needed. Among the alre ... More
Presented by Daniel GUBERMAN on 14/7/2017 at 4:45
We present a phenomenological model of cosmic-ray (CR) transport based on inhomogeneous diffusion. Our model is strongly motivated and driven by the large-scale trends on proton normalization and slope inferred by Fermi-LAT gamma-ray data. In particular, the model provides a solution to the long-standing gradient problem in the outer Galactic plane, i.e. the tension between the observed radial pro ... More
Presented by Daniele GAGGERO
An excess of gamma rays from the Inner Galaxy in the Fermi LAT data has been identified, the GCE. This emission has been interpreted as a possible signature of the annihilation of dark matter particles, or as originating from a collection of unresolved point sources, such as gamma-ray millisecond pulsars. We explore the clustering properties of the diffuse emission arising from a population of gam ... More
Presented by German GOMEZ-VARGAS on 18/7/2017 at 7:45
The High Energy Stereoscopic System (H.E.S.S.) has been searching for counterparts of Gamma Ray Bursts (GRBs) for many years. In 2012 the system was upgraded with a fifth 28m diameter telescope which is equipped with stronger motors for rapid repointing. Its large light collection area of 600 m^2 improves the sensitivity to low-energy gamma-rays and even extends the energy range below 100 GeV. The ... More
Presented by Clemens HOISCHEN on 18/7/2017 at 5:30
The HAWC Gamma-Ray Observatory has reported the discovery of TeV gamma-ray emission extending several degrees around the positions of Geminga and B0656+14 pulsars. Assuming these gamma rays are produced by inverse Compton scattering off low-energy photons in electron halos around the pulsars, we determine the diffusion of electrons and positrons in the local interstellar medium. We will present th ... More
Presented by Francisco SALESA GREUS on 15/7/2017 at 8:00
The international Cherenkov Telescope Array (CTA) project will provide the scientific community with the next-generation ground-based gamma-ray instrument, allowing exploration of cosmic radiation in the very high energy range from a few tens of GeV to 300 TeV. Southern and northern telescope arrays will be built, providing access to the whole sky. The southern array in Chile will be composed of I ... More
Presented by Helene SOL on 17/7/2017 at 5:45
MAGIC is one of the main detectors for exploring the galactic gamma-ray sky from ground in the energy range of 50 GeV - 50 TeV. It consists of two 17m diameter imaging atmospheric Cherenkov telescopes located at the Roque de los Muchachos Observatory, on the Canary island of La Palma. Thanks to its low energy threshold and excellent sensitivity, MAGIC has discovered a significant number of galacti ... More
Presented by Marcos LÓPEZ MOYA on 15/7/2017 at 4:30
We present the analysis methodology and preliminary results of the gamma-ray event analysis using the CALorimetric Electron Telescope (CALET). CALET, a 30 radiation length deep calorimeter, was deployed aboard the International Space Station (ISS) in August 2015. In this work we demonstrate the sensitivity of CALET to gamma-rays, the efficiency of separation between gamma-ray and charged particle ... More
Presented by Nicholas CANNADY on 13/7/2017 at 8:00
The TeV gamma ray sky is observable by recording footprints of extensive air showers with an array of particle detectors. In the northern hemisphere there are currently two projects employing this technique: The HAWC gamma ray observatory which is currently operational in Mexico and LHAASO in the Sichuan region in China which is currently under development. In the southern hemisphere several effor ... More
Presented by Harm SCHOORLEMMER on 17/7/2017 at 8:15
Access to the photon polarisation in the 1-100 MeV energy range is a challenge for the next generation of space telescopes. The current telescopes in space are almost blind in this energy range, mainly due to the degradation of the angular resolution of e+e- pair and due to elastic scattering in the matter. Pair-conversion detector technologies as gaseous detectors are a promising alternative to t ... More
Presented by David ATTIÉ on 19/7/2017 at 4:30
Pulsar wind nebulae (PWNe) are among the most extreme particle accelerators in galaxies, are recognized as multi-TeV electron/positron sources, and are one of the dominant classes of Galactic gamma-ray sources. Vela X is a nearby PWN at 290 pc from the Earth with large apparent size (> 1 deg). The H.E.S.S. array of imaging atmospheric Cherenkov telescopes has detected Vela X as one of the brightes ... More
Presented by Luigi TIBALDO on 15/7/2017 at 7:45
During their propagation through the Galaxy, cosmic-rays (CRs) interact with the interstellar gas, losing energy and creating secondary particles. These secondary particles are then used to constrain the origin and propagation of CRs as well as provide signatures of new and interesting physics. Until now, most modeling of CR propagation have used a 2D galactocentric cylindrically symmetric models ... More
Presented by Guðlaugur JÓHANNESSON on 18/7/2017 at 5:15
The new generation gamma ray telescopes, such as LHAASO, HISCORE and CTA will have a much larger sensitivity at energies above 30 TeV with respect to the current instruments, allowing the study of the gamma ray sky in an energy range almost completely unexplored. The observations will focus both on individual gamma ray sources and (in case of large field of view detectors like air shower arrays) o ... More
Presented by Silvia VERNETTO on 18/7/2017 at 5:30
The Cherenkov Telescope Array (CTA) is the next generation ground-based gamma-ray observatory. It will provide an order of magnitude better sensitivity and an extended energy coverage, 20 GeV--300 TeV, relative to current experiments. Imaging Atmospheric Cherenkov Telescopes (IACTs), despite featuring an excellent sensitivity, are characterized by a limited field of view which makes the blind sear ... More
Presented by Tarek HASSAN on 18/7/2017 at 9:15
The High Altitude Water Cherenkov (HAWC) gamma-ray observatory consists of 300 water Cherenkov detectors and has been fully operational since March 2015 in central Mexico. It detects cosmic- and gamma-ray showers in the TeV range. For multi-TeV energies, the shower reconstruction and hence the performance of the detector is affected by the partial containment of the showers within the array. To im ... More
Presented by Vikas JOSHI on 13/7/2017 at 5:30
The present HESSII era of the HESS collaboration follows from the successful upgrade of the HESS array, and the first published results obtained with this new instrument. Thanks to these achievements, a lower energy threshold with HESSII than that obtained previously with HESSI has been clearly demonstrated. The success of these developments has now opened up a whole new lower-energy window to the ... More
Presented by Andrew TAYLOR on 13/7/2017 at 5:00
Eta Car is a colliding-wind binary that shows non-thermal emission from hard X-rays to high-energy gamma rays. The gamma-ray spectrum exhibits two spectral components, where the high-energy component extends up to 300 GeV. Previous observations of Eta Car with the High Energy Stereoscopic System (H.E.S.S.) resulted in upper limits. With the addition of the large 28-m central telescope to the H.E.S ... More
Presented by Eva LESER on 13/7/2017 at 8:45
Extraterrestrial gamma-ray astronomy is now a source of new knowledge in the fields of cosmophysics, astrophysics, cosmic-ray physics, and the nature of dark matter. The next absolutely necessary step in the development of extraterrestrial high-energy gamma-ray astronomy is the improvement of the physical and technical characteristics of gamma-ray telescopes in order to improve the angular and ene ... More
Presented by Nikolay TOPCHIEV on 14/7/2017 at 5:30
Designed to study the sky at very high energies, the H.E.S.S. experiment detects gamma-rays of energies from few tens of GeV up to hundreds of TeV using five Imaging Atmospheric Cherenkov Telescopes (IACT). The Crab Nebula is one of the sources which has been regularly monitored by the H.E.S.S. telescopes since the array started to operate. The Fermi-LAT satellite have reported on the detection of ... More
Presented by Floriana ZEFI on 15/7/2017 at 8:30
Gamma-rays with energy exceeding 100 GeV emitted by extragalactic sources initiate cascades in the intergalactic medium. The angular and temporal distribution of the cascade photons that arrive at the Earth depend on the strength and configuration of extragalactic magnetic fields in the line of sight. For weak enough fields, extended emission around the source (halo) is expected to be detectable, ... More
Presented by Foteini OIKONOMOU on 19/7/2017 at 5:00
With the installation of a new 28-m diameter imaging atmospheric Cherenkov telescope in the middle of the array, the H.E.S.S. instrument has entered since 2012 into its Phase II. The fifth large-size telescope is particularly important to lower the threshold energy of the array, and is thus an unique instrument to observe low-frequency-peaked blazars, such as flat-spectrum radio-quasars (FSRQs), w ... More
Presented by Matteo CERRUTI on 13/7/2017 at 5:45
The Large Area Telescope (LAT) on board the Fermi satellite conducted the deepest all-sky survey in gamma rays so far. Despite outstanding achievements in assigning source types, 1010 sources in the Third Fermi-LAT Source Catalog (3FGL) remain without plausible associations, and 573 sources are associated to active galaxies of uncertain type. Assigning blazar classes to unassociated and uncertain ... More
Presented by Sabrina EINECKE on 18/7/2017 at 8:15
Probing the high energy emission processes of blazars through their variability relies crucially on long-term monitoring. We present unprecedented light curves from unbiased observations of very high energy fluxes from the blazars Mrk 421 and Mrk 501 based on a joint analysis of data from the First G-APD Cherenkov Telescope (FACT) and the High Altitude Water Cherenkov (HAWC) Observatory. Thanks to ... More
Presented by Daniela DORNER on 13/7/2017 at 5:15
We present results of a search for PeV gamma ray point sources with the IceCube observatory, presently the most sensitive facility for PeV gamma ray sources in the southern hemisphere. This includes a general search over IceCube's field of view, as well as tests for correlations with TeV sources detected by H.E.S.S. and neutrino events from IceCube's high energy starting event sample. As the atten ... More
Presented by Zachary GRIFFITH on 19/7/2017 at 8:15
The High-Altitude Water-Cherenkov (HAWC) experiment is a TeV gamma-ray observatory located 4100 m above sea level on the Sierra Negra mountain in Puebla, Mexico. The detector consists of 300 water-filled tanks, each instrumented with 4 photomultiplier tubes that utilize the water-Cherenkov technique to detect atmospheric air showers produced by cosmic gamma rays. Construction of HAWC was completed ... More
Presented by Jordan GOODMAN on 15/7/2017 at 5:15
The gamma-ray energy range from a few hundred keV to a few hundred MeV has remained largely unexplored since the pioneering but limited observations by COMPTEL on the CGRO (1991-2000). Fundamental astrophysics questions can be addressed by a mission in the MeV range, from astrophysical jets and extreme physics of compact objects to a large population of unidentified objects. To address these quest ... More
Presented by Alexander MOISEEV on 14/7/2017 at 5:45
"TeV binary LS I +61 303 has a compact star in an eccentric orbit around a Be star about 2kpc away. LS I +61 303 exhibits modulated gamma-ray emission around its 26.5 days orbit, mostly detectable at TeV energies around its apastron passage, with maximum flux during  $phi$=0.55-0.65 phase range. Multiple flaring episodes at TeV energies have been observed since its detection in 2006 with nightl ... More
Presented by David KIEDA on 13/7/2017 at 7:45
The Cygnus arm of our galaxy is a source-rich and complex region hosting multiple gamma-ray source types such as pulsar wind nebulae(PWN), supernova remnants, binary systems, and star clusters. The High Altitude Water Cherenkov(HAWC) observatory has been collecting data continuously since 2014, and has reported five sources within the Cygnus region. Several other instruments have also observed gam ... More
Presented by Binita HONA on 15/7/2017 at 5:30
The Compton Spectrometer and Imager (COSI) is a balloon-borne soft gamma-ray (0.2-5 MeV) telescope designed to study astrophysical sources of nuclear line emission and gamma-ray polarization. The heart of COSI is a compact array of cross-strip germanium detectors (GeDs), providing excellent spectral resolution (0.3% at 662 keV) and capability of tracking photon scattering history with full 3D posi ... More
Presented by Jeng-Lun CHIU on 19/7/2017 at 9:15
The Cygnus region of the galaxy is one of the richest regions of gas and star formation and is the brightest region of diffuse GeV emission in the northern sky. VERITAS has conducted deep (approximately 300 hours of live time) observations in the direction of Cygnus region reaching an average sensitivity of a few percent of the Crab nebula flux. We present the results of these observations and an ... More
Presented by Ralph BIRD on 17/7/2017 at 9:15
We present a new and deep analysis of the pulsar wind nebula (PWN) HESS J1825-137 with a comprehensive data set of almost 400 hours taken with the H.E.S.S. array between 2004 and 2016. The large amount of data, and the inclusion of low-threshold H.E.S.S. II data allows us to include a wide energy range of more than 2.5 orders of magnitude, ranging from 150 GeV up to 70 TeV. We exploit this rich da ... More
Presented by Alison MITCHELL on 15/7/2017 at 8:15
The First G-APD Cherenkov Telescope (FACT) is pioneering the usage of silicon photo multipliers (SiPMs also known as G-APDs) for the imaging atmospheric Cherenkov technique. It is located at the Observatorio Roque de los Muchachos on the Canary island of La Palma. Since first light in October 2011, it is monitoring bright TeV blazars in the northern sky. By now, FACT is the only imaging atmospheri ... More
Presented by Maximilian NÖTHE on 17/7/2017 at 7:30
We present a search for diffuse PeV gamma rays arising from interactions of cosmic rays with the interstellar gas in the Galactic plane. We analyze air shower data recorded by the IceCube Observatory from May 2012 to May 2016 in the energy range of 0.63 PeV to 100 PeV for the presence of gamma ray showers. Characteristics of air shower signals, recorded by IceTop as well as in-ice IceCube array, a ... More
Presented by Hershal PANDYA on 19/7/2017 at 5:30
CTA is the next generation high-energy gamma-ray observatory, which consists of two sites, Paranal, Chile in South and La Palma, Spain in North to establish all sky coverage at the very high energy range. With the baseline design of CTA, we will build four large size telescopes at the center of the array on both sites. The Large Size Telescopes (LST) will detect with high sensitivity gamma rays wi ... More
Presented by Masahiro TESHIMA on 14/7/2017 at 8:00
The detection of an astrophysical flux of high-energy neutrinos by IceCube is a major step forward in the search for the origin of cosmic rays, as this emission is expected to originate in hadronic interactions taking place in or near cosmic-ray accelerators. No neutrino point sources, or a significant correlation with known astrophysical objects, have been identified in the IceCube data so far th ... More
Presented by Marcos SANTANDER on 18/7/2017 at 8:45
Based on 18 months of data from the DArk Matter Particle Explorer (DAMPE), we are able to produce a GeV gamma-ray sky map showcasing the powerful e/p (e/gamma) discrimination and high space resolution of DAMPE. Bright gamma-ray point sources of various kinds are identified in the map. We discuss the potential usage of DAMPE’s photon observation in both calibration and science, including boresigh ... More
Presented by Shijun LEI on 18/7/2017 at 5:45
Fast variations of gamma-ray flux from Active Galactic Nuclei and Gamma-Ray Bursts can constrain Lorentz Invariance Violation (LIV) because of the delayed (or advanced) arrival of photons with higher energies: this approach has lead to the current world-best limits on the energy scale of Quantum Gravity. Here we report on constraints on LIV studying the gamma-ray emission up to TeV energies from t ... More
Presented by Javier RICO
Fast variations of gamma-ray flux from Active Galactic Nuclei and Gamma-Ray Bursts can constrain Lorentz Invariance Violation (LIV) because of the delayed (or advanced) arrival of photons with higher energies: this approach has lead to the current world-best limits on the energy scale of Quantum Gravity. Here we report on constraints on LIV studying the gamma-ray emission up to TeV energies from t ... More
Presented by Markus GAUG on 17/7/2017 at 5:00
The Large Array Telescope for Tracking Energetic Sources (LATTES), is a novel concept for a hybrid EAS array detector, composed of a Resistive Plate Counter and a Water Cherenkov Detector, planned to cover gamma-rays from less than 100 GeV up to 100 TeVs. This experiment, to be installed at high altitude in South America, could cover the existing gap in sensitivity between satellite and ground arr ... More
Presented by Ruben CONCEIÇÃO on 17/7/2017 at 8:45
ALTO is a concept/project in the exploratory phase since 2013 aiming to build a wide-field VHE gamma-ray observatory at very high altitude in the Southern hemisphere. The operation of such an observatory will complement the Northern hemisphere observations performed by HAWC and will make possible the exploration of the central region of our Galaxy and search for Pevatrons, and to search for extend ... More
Presented by Satyendra THOUDAM on 17/7/2017 at 8:30
The H.E.S.S. gamma-ray observatory has opened a window on our Galaxy at very high energies (VHEs) with resolutions and sensitivities never before possible, discovering a rich zoo of source classes as well as a number of yet to be identified VHE emitters. The rich H.E.S.S. data set obtained after more than 14 years of observations, together with the advanced data analysis techniques developed in th ... More
Presented by Robert PARSONS on 15/7/2017 at 4:45
The First G-APD Cherenkov Telescope (FACT) is monitoring blazars at TeV energies. Thanks to the observing strategy, the automatic operation and the usage of solid state photosensors (SiPM, aka G-APDs), the duty cycle of the instrument has been maximized and the observational gaps minimized. This provides an unprecedented, unbiased data sample of more than 8600 hours of data of which more than 2350 ... More
Presented by Daniela DORNER on 18/7/2017 at 8:30
The HAWC (High Altitude Water Cherenkov) observatory recently published their second source catalog with 39 very high energy gamma-ray sources based on 507 days of exposure time. Among these, there were sixteen sources that are more than one degree away from any known TeV source. We studied thirteen of these sources without known counterparts with VERITAS and Fermi-LAT data. VERITAS, an array of f ... More
Presented by Nahee PARK on 15/7/2017 at 5:00
Cosmic rays propagating in the Milky Way lose energy via interactions with the interstellar medium and magnetic fields. These losses produce emissions that span the electromagnetic spectrum, and are an invaluable tool for understanding the intensities and spectra of cosmic rays in distant regions, far beyond those probed by direct cosmic ray measurements. We present updates on the study of cosmic ... More
Presented by Elena ORLANDO on 14/7/2017 at 5:00
Blazars are extremely variable objects emitting radiation across the electromagnetic spectrum and showing variability on time scales from minutes to years. Simultaneous multi-wavelength observations are crucial for understanding the emission mechanisms. In particular the study of their TeV emission is relevant to test the dominant radiative process at such energies (e.g. leptonic models predict co ... More
Presented by Ruben ALFARO on 17/7/2017 at 7:45
Primordial black holes are black holes that may have formed from density fluctuations in the early universe. It has been theorized that black holes slowly evaporate. If primordial black holes of initial mass of 10^14g were formed, their evaporation would end in this epoch, in a bright burst of very-high-energy gamma rays. A Cherenkov telescope experiment like VERITAS can look for these primordial ... More
Presented by Simon ARCHAMBAULT on 19/7/2017 at 8:30
The measurement of Galactic diffuse TeV gamma-ray emission would provide strong constraints on the acceleration and propagation of high-energy cosmic rays within our Galaxy. The High Altitude Water Cherenkov (HAWC) Observatory, located in central Mexico at 4100 m above sea level, is sensitive to gamma rays between a few hundreds GeV and 100 TeV. Thanks to its large field of view of 2 steradians an ... More
Presented by Hao ZHOU
The measurement of Galactic diffuse TeV gamma-ray emission would provide strong constraints on the acceleration and propagation of high-energy cosmic rays within our Galaxy. The High Altitude Water Cherenkov (HAWC) Observatory, located in central Mexico at 4100 m above sea level, is sensitive to gamma rays between a few hundreds GeV and 100 TeV. Thanks to its large field of view of 2 steradians an ... More
Presented by Hao ZHOU on 14/7/2017 at 8:30
One of the most outstanding questions in the field of gamma-ray bursts (GRBs) concerns about the composition of relativistic jets that are responsible for producing bright prompt gamma-rays and X-ray flares. Among two possible (i.e., matter-dominated or Poynting-flux-dominated) outflows, it is possible to expect a signature of bulk acceleration of the emitting region only in the case of a Poynting ... More
Presented by Z. Lucas UHM on 18/7/2017 at 4:30
High-energy cosmic-ray (CR) protons and electrons interact with the interstellar gas or the interstellar radiation field and produce diffuse gamma rays. Since the interstellar medium (ISM) is transparent to these high-energy photons, GeV gamma rays are a powerful probe to study the ISM and Galactic CRs. In order to study the spatial and spectral distributions of CRs through gamma rays, either in t ... More
Presented by Tsunefumi MIZUNO on 19/7/2017 at 4:45
Cosmic rays (CRs) in the Galaxy are thought to be generated via diffusive shock acceleration. Gamma-ray observations have revealed that protons and/or electrons are accelerated to energies up to 100 TeV in supernova remnants (SNRs), and hence SNRs are the most plausible source of CR production. Whereas low-energy cosmic rays (LECRs) below the ~MeV band have important information on the initial acc ... More
Presented by Kumiko NOBUKAWA on 18/7/2017 at 5:00
The extragalactic background light (EBL) is the radiation accumulated through the history of the Universe in the wavelength range from the ultraviolet to the far infrared. Local foregrounds make the direct measurement of the diffuse EBL notoriously difficult, while robust lower limits have been obtained by adding up the contributions of all the discrete sources resolved in deep infrared and optica ... More
Presented by Abelardo Moralejo OLAIZOLA on 19/7/2017 at 4:45
A recent study of the diffuse gamma-ray emission in the central molecular zone by using very high energy (VHE, E > 0.1 TeV) H.E.S.S. data suggests that the Galactic Center (GC) is the most plausible supplier of Galactic ultra-relativistic cosmic rays (CRs) up to the knee at about 10$^{15}$ eV (PeV). However, the GC might not be the only source capable to accelerate CRs up to PeV energies in the Ga ... More
Presented by Ekrem Oguzhan ANGUNER on 17/7/2017 at 5:15
The physics motivations and advantages of the new TAIGA (Tunka Advanced Instrument for cosmic ray physics and Gamma Astronomy) detector are presented. TAIGA aims to addresses gamma-ray astronomy at energies from a few TeV to several PeV, as well as cosmic ray physics from 100 TeV to several EeV. For the energy range 30 – 200 TeV the sensitivity of 5 km^2 area TAIGA detector for the detection of ... More
Presented by Nikolay BUDNEV on 18/7/2017 at 4:30
Gamma Cygni SNR (G78.2+2.1) is a middle-aged SNR (~7000 years old) situated in the Cygnus region. The high-energy observations by VERITAS and Fermi-LAT revealed a complex, energy-dependent morphology of the SNR in the GeV-TeV band, different from that observed in X-rays. G78.2+2.1 also hosts the pulsar PSR J2021+4026, which is the only variable gamma-ray pulsar known to date. Using recent observat ... More
Presented by Marcel STRZYS on 17/7/2017 at 4:45
We propose a coherent jet model for radio loud AGNs. This model is based on the assumption that the jet is composed of two flows: an external MHD plasma, surrounding an internal highly relativistic plasma of electron-positrons. The leptons present in the spine, responsible of most of the emission, are supposed to be continuously heated via diffuse acceleration along the jet. The model is thus natu ... More
Presented by Thomas VUILLAUME on 13/7/2017 at 9:15
Diffuse gamma-ray emission is a viable tool to probe cosmic rays and their propagation in the Milky Way. In the MeV to GeV energy range the Galactic diffuse emission has been explored in great detail by Fermi-LAT. At very high energies (VHE), gamma-ray sources dominate the TeV sky. Any VHE large-scale diffuse emission is thus likely to consist to a large fraction of gamma-ray sources that are unre ... More
Presented by Kathrin EGBERTS on 19/7/2017 at 5:15
Gamma-ray bursts (GRBs) are the most luminous explosions in the Universe, yet many of their basic properties remain poorly understood, particularly for short GRBs with durations less than ~2 sec. Very-high-energy (VHE) gamma rays from GRBs are expected to provide crucial new information on the physical mechanisms of energy dissipation, particle acceleration and radiation in these enigmatic objects ... More
Presented by Susumu INOUE on 18/7/2017 at 5:15
The Cherenkov Telescope Array is expected to lead to the detection of many new supernova remnants (SNRs) in the TeV and multi--TeV range. In addition to the individual study of each SNR, the study of these objects as a population can help constraining the parameters describing the acceleration of particles and increasing our understanding of the mechanisms involved. We present Monte Carlo simulati ... More
Presented by Pierre CRISTOFARI on 17/7/2017 at 5:30
The composite supernova remnant (SNR) MSH 15-52 comprises the bright X-ray pulsar wind nebula (PWN) of PSR B1509-58, surrounded by a shell which is a prominent object in the radio domain. H.E.S.S. had discovered extended very-high-energy (VHE) gamma-ray emission coincident with the PWN. With additional H.E.S.S. observations performed since the 2005 discovery paper, we study the properties of the e ... More
Presented by Michelle TSIROU on 15/7/2017 at 9:00
Recently it was observed (A. Furniss et al., MNRAS, 446, 2267 (2015)) that Fermi LAT blazars with relatively hard (gamma<3) observed spectra above 10 GeV are predominantly located towards the directions to the large scale structure voids and, moreover, the observed flux of >10 GeV gamma-rays is usually greater for the case of such directions. This effect may be interpreted in the framework of the ... More
Presented by Timur DZHATDOEV on 18/7/2017 at 8:00
The pulsed radiation from PSR B0833-45 (Vela) has a phased-averaged spectral energy distribution of an apparently simple structure across a wide energy range, from optical light to hard gamma-rays. However, the Vela pulses in narrow energy bands reveal astonishing complexity of the directional pattern of the radiation. These pulses are, therefore, a unique clue to the underlying radiative processe ... More
Presented by Bronislaw RUDAK on 15/7/2017 at 7:30
Sgr A*, the variable source at the center of the Milky Way galaxy, is the closest supermassive black hole candidate which is interesting to understand the origin of outflows and flare phenomena in low luminosity AGNs. It has been under frequent study and the black hole astrophysics community awaits for results from further simultaneous multiwavelength monitoring in April 2017. For this purpose, we ... More
Presented by Chandra Bahadur SINGH on 19/7/2017 at 8:00
Statistical tools like the lognormal flux distribution, the linear rms-flux relation and the (broken) power-law spectral densities (PSDs) obtained from observations in X-ray/Ultraviolet/Optical emission of radio-quiet AGNs and other compact sources are normally attributed to the multiplicative combination of fluctuations in the accretion disk. Similar characteristics have been seen in some blazars ... More
Presented by Pankaj KUSHWAHA on 18/7/2017 at 7:30
The very to ultra high energy gamma-ray regime up to several 100 TeV is the key to spectrally resolve the cutoff regime of the long-sought Pevatrons, the Galactic cosmic-ray PeV accelerators. One component of the TAIGA hybrid detector is the TAIGA-HiSCORE shower-front sampling timing array, which currently consists of 28 wide angle (0.6 sr) air Cherenkov timing stations distributed on an area of 0 ... More
Presented by Vasily PROSIN on 13/7/2017 at 5:15
The foreseen implementations of the Small Size Telescopes (SST) in CTA will provide unique insights into the highest energy gamma-rays offering fundamental means to discover and understand the sources populating the Galaxy and our local neighborhood. Aiming at such a goal, the SST-1M is one of the three different implementations that are being prototyped and tested for CTA.  SST-1M is a ... More
Presented by Cyril ALISPACH on 14/7/2017 at 8:15
The High-Energy Stereoscopic System (H.E.S.S.) has detected an extended region of diffuse TeV gamma-ray emission along the Ridge in the central 200 parsec of the Galaxy, indicating a petaelectrovolt accelerators (‘PeVatrons’) in the Galactic Center. We assume a past hypernova locating in the Galactic Center, since an individual supernova remanent can not accelerate particles to PeV energy over ... More
Presented by Haoning HE on 19/7/2017 at 7:45
Any considerations on propagation of particles through the Universe must involve particle interactions: processes leading to production of particle cascades. While one expects existence of such cascades, the state of the art cosmic-ray research is oriented purely on a detection of single particles, gamma rays or associated extensive air showers. The natural extension of the cosmic-ray research wit ... More
Presented by Kévin Almeida CHEMINANT on 19/7/2017 at 8:45
The TAIGA (Tunka Advanced Instrument for cosmic rays and Gamma-Astronomy) detector is aiming to study the gamma and cosmic rays at the high-energy end of galactic sources. Deployment of this multi-component, hybrid array started several years ago in Tunka Valley, ~50 km from the lake Baikal in Siberia. The Timing Cherenkov array TAIGA- HiSCORE, part of the TAIGA, currently consists of 28 wide-angl ... More
Presented by Lyubov SVESHNIKOVA on 13/7/2017 at 4:45
The resolution power of current Imaging Atmospheric Cherenkov Telescopes is presently restricted to scales of a few arcmin. Measuring the extension of VHE sources is limited by the uncertainties in the characterisation of the instrument Point Spread Function (PSF), which varies strongly with observation and instrument conditions. Employing newly developed simulation and analysis techniques we subs ... More
Presented by Markus HOLLER on 15/7/2017 at 8:45
We report the first ground-based observation of the CATS-LIDAR onboard the ISS by the TAIGA-HiSCORE gamma-ray facility, and the MASTER-Tunka Robotic telescope. HiSCORE detects unscattered laser light directly from the ISS, at up to km-scale distance from the laser beam spot on ground. The ISS-LIDAR turns out to be a unique calibration tool, in particular to verify the absolute astronomical pointin ... More
Presented by Ralf WISCHNEWSKI on 13/7/2017 at 5:00
The Cherenkov Telescope Array (CTA) will be the next-generation gamma-ray observatory, investigating gamma-ray and cosmic ray astrophysics at energies from 20 GeV to more than 300 TeV. The observatory, consisting of large arrays of imaging atmospheric Cherenkov telescopes in both the southern and northern hemispheres, will provide full-sky coverage and will achieve a sensitivity improved by up to ... More
Presented by Rene ONG on 14/7/2017 at 7:45
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