Conveners
19 - VHE & CR: Blazars and EBL
- Teresa Montaruli
19 - VHE & CR: Blazars and EBL
- Elisa Prandini (University of Geneva)
19 - VHE & CR: VHE observations
- Teresa Montaruli
19 - VHE & CR: VHE observations
- Elisa Prandini (Universite de Geneve (CH))
19 - VHE & CR: CR and astrophysical neutrinos
- Teresa Montaruli
19 - VHE & CR: CR and astrophysical neutrinos
- Matthieu Heller (Universite de Geneve (CH))
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Elisa Kay Pueschel (University College Dublin)06/12/2015, 14:00TalkThe 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...Go to contribution page
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Josefa Becerra Gonzalez (NASA GSFC)06/12/2015, 14:21TalkThe 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...Go to contribution page
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Pierre Colin (MPI fuer Physik)06/12/2015, 14:42TalkRapid 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...Go to contribution page
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Floriana Zefi (LLR - Ecole Polytechnique)06/12/2015, 15:03TalkWe 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...Go to contribution page
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Frank Rieger (MPIK and Univ. of Heidelberg)06/12/2015, 15:24TalkThe 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...Go to contribution page
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Gareth Hughes (ETH Zurich)06/12/2015, 16:35TalkThe 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...Go to contribution page
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Dr Marina Manganaro (IAC)06/12/2015, 16:55TalkS5 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...Go to contribution page
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Giovanna Pedaletti (DESY)06/12/2015, 17:15TalkThe 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 <...Go to contribution page
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Josefa Becerra Gonzalez (NASA GSFC)06/12/2015, 17:35TalkThe 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...Go to contribution page
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Antonio Stamerra (INAF-OATo / SNS-Pisa)06/12/2015, 17:55TalkFor 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...Go to contribution page
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Gareth Hughes (ETH Zurich)06/12/2015, 18:15TalkPG 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...Go to contribution page
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Omar Kurtanidze (Abastumani Observatory)06/12/2015, 18:35PosterTo 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...Go to contribution page
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Jill Chevalier (LAPP)07/12/2015, 14:00TalkThe 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...Go to contribution page
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Oscar Blanch (IFAE)07/12/2015, 14:25TalkMAGIC is a ground-based astrophysics instrument for measuring gamma rays in the energy range ~ 35 GeV - 50 TeV. It is the first instrument paving the road into the sub-100 GeV gamma-ray sky. MAGIC consists of two 17m diameter, F/1.03 imaging atmospheric Cherenkov telescopes, which are separated by 85m distance and are located at 2200m a.s.l. in the Roque de los Muchachos European North...Go to contribution page
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John Quinn (University College Dublin)07/12/2015, 14:50TalkVERITAS 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,...Go to contribution page
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Dr Robert Lauer (University of New Mexico)07/12/2015, 15:15TalkThe 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...Go to contribution page
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Lucie Gerard07/12/2015, 16:15TalkThe Cherenkov Telescope Array (CTA) is the next-generation observatory for ground-based gamma-ray astronomy. A Key Science Program (KSP) of observations will be conducted, providing legacy data sets of benefit to the entire astronomical community. This contribution presents the extra-galactic science addressed in the CTA KSP. The objectives contain targeted observations of active galactic...Go to contribution page
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Matthieu Heller (Universite de Geneve (CH))07/12/2015, 16:40TalkThe 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...Go to contribution page
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Dr Saverio Lombardi (OAR-INAF, ASDC)07/12/2015, 17:00TalkIn 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...Go to contribution page
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Markus Boettcher (North-West University)07/12/2015, 17:20TalkThis 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...Go to contribution page
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Foteini Oikonomou07/12/2015, 17:45TalkGamma-rays with energy exceeding 100 GeV emitted by extragalactic sources, such as blazars, 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 (EGMFs) in the line of sight. For weak enough fields, extended emission around the source (halo)...Go to contribution page
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Dr Maria Petropoulou (Purdue University)08/12/2015, 14:00TalkBlazars, 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...Go to contribution page
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Zhuo Li (Peking University)08/12/2015, 14:25TalkThe 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...Go to contribution page
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Foteini Oikonomou08/12/2015, 14:45TalkUltra-high energy (UHE) neutrinos and photons travel undeflected through cosmic magnetic fields, and point directly to the sources in which they were produced. As such, they have the potential to unveil the locations of the still unknown sources of UHE cosmic rays. The surface detector of the Pierre Auger Observatory is sensitive to UHE neutrinos and photons with energies above 1 EeV and 10...Go to contribution page
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Dr Daniele VIVOLO (INFN Napoli)08/12/2015, 15:05TalkThe 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...Go to contribution page
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Sergio Petrera (University of L'Aquila)08/12/2015, 15:25TalkThe 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...Go to contribution page
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Antonio Surdo (INFN - Lecce (IT))08/12/2015, 16:15TalkThe 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...Go to contribution page
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Jörg Paul Rachen (IMAPP / Radboud University Nijmegen)08/12/2015, 16:35TalkIt 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...Go to contribution page
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yoann genolini (LAPTh)08/12/2015, 16:55TalkPAMELA 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...Go to contribution page
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Michael Kachelriess (NTNU)08/12/2015, 17:15TalkI 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...Go to contribution page
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Dr Rafik Sedrati (University of Souk Ahras, Facilty of science and technology)08/12/2015, 17:35Posterseverel recent experience such as PAMELA, FERMI-LAT, AMS02 have given a very accurate measurement of the spectrum of primary cosmic ray electrons and positrons.have reported a clear excess in the flux of positron fraction up to 100 GeV which leads to the emergence of a debate about the existence and the source of this excess: could come from nearby pulsars or dark-matter annihilation ?? Most...Go to contribution page
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Ingyin Zaw (NYU Abu Dhabi)08/12/2015, 17:38PosterStudies 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...Go to contribution page