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Now showing items 11-20 of 22
Characterizing the γ-ray long-term variability of PKS 2155-304 with H.E.S.S. and Fermi-LAT
(EDP Sciences, 2017)
Studying the temporal variability of BL Lac objects at the highest energies provides unique insights into the extreme physical processes occurring in relativistic jets and in the vicinity of super-massive black holes. To ...
EBL inhomogeneity and hard-spectrum gamma-ray sources
(IOP Publishing, 2017)
The unexpectedly hard very-high-energy (VHE; E > 100 GeV) γ-ray spectra of a few distant blazars have been interpreted as evidence of a reduction of the γγ opacity of the universe due to the interaction of VHE γ-rays with ...
H.E.S.S. discovery of very high energy γ-ray emission from PKS 0625−354
(Oxford Univ Press, 2018)
PKS 0625−354 (z = 0.055) was observed with the four High Energy Stereoscopic System (H.E.S.S.) telescopes in 2012 during 5.5 h. The source was detected above an energy threshold of 200 GeV at a significance level of 6.1σ. ...
Polarization signatures of relativistic magnetohydrodynamic shocks in the blazar emission region. I. Force-free helical magnetic fields
(IOP, 2016)
The optical radiation and polarization signatures in blazars are known to be highly variable during flaring activities. It is frequently argued that shocks are the main driver of the flaring events. However, the spectral ...
Particle diffusion and localized acceleration in inhomogeneous AGN jets. II. Stochastic variation
(Oxford Univ Press, 2016)
We study the stochastic variation of blazar emission under a 2D spatially resolved leptonic jet model we previously developed. Random events of particle acceleration and injection in small zones within the emission region ...
Leptonic and lepto-hadronic modeling of the 2010 November flare from 3C 454.3
(AAS, 2016)
In this study, we use a one-zone leptonic and a lepto-hadronic model to investigate the multi-wavelength emission and prominent flare of the flat spectrum radio quasar 3C 454.3 in 2010 November. We perform a parameter study ...
Attenuation of TeV γ-rays by the starlight photon field of the host galaxy
(Oxford Univ Press, 2017)
The absorption of TeV γ-ray photons produced in relativistic jets by surrounding soft photon fields is a long-standing problem of jet physics. In some cases, the most likely emission site close to the central black hole ...
Systematic physical characterization of the γ-ray spectra of 2FHL blazars
(IOP Publishing, 2019)
We test different physically motivated models for the spectral shape of the γ-ray emission in a sample of 128 blazars with known redshifts detected by the Fermi Large Area Telescope (LAT) at energies above 50 GeV. The first ...
Possible accretion disk origin of the emission variability of a blazar jet
(IOP Publishing, 2018)
We analyze X-ray light curves of the blazar Mrk 421 obtained from the Soft X-ray Imaging Telescope (SXT) and the Large Area X-ray Proportional Counter (LAXPC) instrument on board the Indian space telescope AstroSat and ...
Leptonic and hadronic modeling of Fermi-LAT hard spectrum quasars and predictions for high-energy polarization
(IOP Publishing, 2018)
We present the results of a study of the time-averaged spectral energy distributions (SEDs) of eight flat spectrum
radio quasars (FSRQs) present in the second catalog of high energy sources detected beyond 50 GeV by the ...