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))
Elisa Kay Pueschel
(University College Dublin)
12/15/15, 2:00โฏPM
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...
Josefa Becerra Gonzalez
(NASA GSFC)
12/15/15, 2:21โฏPM
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...
Pierre Colin
(MPI fuer Physik)
12/15/15, 2:42โฏPM
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...
Floriana Zefi
(LLR - Ecole Polytechnique)
12/15/15, 3:03โฏPM
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...
Frank Rieger
(MPIK and Univ. of Heidelberg)
12/15/15, 3:24โฏPM
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...
Gareth Hughes
(ETH Zurich)
12/15/15, 4:35โฏPM
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...
Dr
Marina Manganaro
(IAC)
12/15/15, 4:55โฏPM
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...
Giovanna Pedaletti
(DESY)
12/15/15, 5:15โฏPM
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 <...
Josefa Becerra Gonzalez
(NASA GSFC)
12/15/15, 5:35โฏPM
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...
Antonio Stamerra
(INAF-OATo / SNS-Pisa)
12/15/15, 5:55โฏPM
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...
Gareth Hughes
(ETH Zurich)
12/15/15, 6:15โฏPM
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...
Omar Kurtanidze
(Abastumani Observatory)
12/15/15, 6:35โฏPM
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...
Jill Chevalier
(LAPP)
12/16/15, 2:00โฏPM
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...
Oscar Blanch
(IFAE)
12/16/15, 2:25โฏPM
Talk
MAGIC 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...
John Quinn
(University College Dublin)
12/16/15, 2:50โฏPM
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,...
Dr
Robert Lauer
(University of New Mexico)
12/16/15, 3:15โฏPM
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...
Matthieu Heller
(Universite de Geneve (CH))
12/16/15, 4:40โฏPM
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
Saverio Lombardi
(OAR-INAF, ASDC)
12/16/15, 5:00โฏPM
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...
Markus Boettcher
(North-West University)
12/16/15, 5:20โฏPM
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...
Dr
Maria Petropoulou
(Purdue University)
12/17/15, 2:00โฏPM
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...
Zhuo Li
(Peking University)
12/17/15, 2:25โฏPM
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
Daniele VIVOLO
(INFN Napoli)
12/17/15, 3:05โฏPM
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...
Sergio Petrera
(University of L'Aquila)
12/17/15, 3:25โฏPM
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...
Antonio Surdo
(INFN - Lecce (IT))
12/17/15, 4:15โฏPM
Talk
The CR spectrum has been studied by the ARGO-YBJ experiment in a wide energy range (TeVsโ PeVs) . This study is particularly interesting because not only it allows a better understanding of the so called โkneeโ 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...
Jรถrg Paul Rachen
(IMAPP / Radboud University Nijmegen)
12/17/15, 4:35โฏPM
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...
yoann genolini
(LAPTh)
12/17/15, 4:55โฏPM
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...
Michael Kachelriess
(NTNU)
12/17/15, 5:15โฏPM
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 ฮณ-ray fluxes produced by these CR protons interacting...
Ingyin Zaw
(NYU Abu Dhabi)
12/17/15, 5:35โฏPM
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...
