Related papers: TeV Active Galactic Nuclei: Multifrequency Modelin…
A new TeV source, HESS J1641-463, has been serendipitously discovered in the Galactic plane by the High Energy Stereoscopic System (H.E.S.S.) at a significance level of 8.6 standard deviations. The observations of HESS J1641-463 were…
M87 is the first extragalactic source detected in the TeV gamma-ray domain that is not a blazar, its large scale jet not being aligned to the line of sight. We present here a multi-blob synchrotron self-Compton model accounting explicitly…
The close X-ray selected BL Lac PKS 2155--304 has been observed using the University of Durham Mark 6 very high energy (VHE) gamma ray telescope during 1996 September/October/November and 1997 October/November. VHE gamma rays with energy >…
The VERITAS array of 12-m atmospheric-Cherenkov telescopes is used in an intensive observation program focused on the discovery of VHE (E > 100 GeV) gamma-ray-emitting blazars. Since VERITAS began full-scale operation in 2007, more than…
The prospects for future blazar surveys by next-generation very high energy (VHE) gamma-ray telescopes, such as Advanced Gamma-ray Imaging System (AGIS) and Cherenkov Telescope Array (CTA), are investigated using the latest model of blazar…
During the first 3 years of operation the Gamma-Ray Imaging Detector onboard the AGILE satellite detected several blazars in a high gamma-ray activity: 3C 279, 3C 454.3, PKS 1510-089, S5 0716+714, 3C 273, W Comae, Mrk 421, PKS 0537-441 and…
Milagro and HAWC have detected extended TeV gamma-ray emission around nearby pulsar wind nebulae (PWNe). Building on these discoveries, Linden et al. [1] identified a new source class -- TeV halos -- powered by the interactions of…
This study explores the origins of cosmic rays and their secondary messengers, focusing on the potential role of four BL Lacs W Comae, 1ES 1959+650, PKS 2005-489, and PKS 2155-304 as potential sources of astrophysical neutrinos and gamma…
Radio Galaxies have by now emerged as a new $\gamma$-ray emitting source class on the extragalactic sky. Given their remarkable observed characteristics, such as unusual gamma-ray spectra or ultrafast VHE variability, they represent unique…
We construct a systematic survey of extragalactic \gamma-ray sky at the energies above 100 GeV using the data of Fermi telescope. Such survey has not been previously done by the ground-based Cherenkov gamma-ray telescopes which have,…
Extreme high-frequency peaked BL Lacs (EHBLs) are characterized by a synchrotron peak frequency exceeding $10^{17}$ Hz and a second peak that can be in the energy range of few GeVs to several TeVs. The MAGIC telescopes detected multi-TeV…
The close X-ray selected BL Lac PKS 2155-304 has been observed using the University of Durham Mark 6 very high energy (VHE) gamma ray telescope during 1996 September/October/November and 1997 October/November. VHE gamma rays with energy >…
Radio observations of very high energy (VHE) gamma-ray sources are fundamental to identify and reveal their nature, as well as to understand the physics behind these energetic sources. I will comment on some characteristics of extragalactic…
The recent results from ground based $\gamma$-ray detectors (HESS, MAGIC, VERITAS) provide a population of TeV galactic $\gamma$-ray sources which are potential sources of High Energy (HE) neutrinos. Since the $\gamma$-rays and $\nu$ -s are…
Recent calculations indicate that radio emission from quasars at $z \sim$ 6 - 7 could be detected at much earlier stages of evolution, at $z \sim$ 14 - 15, by the Next-Generation Very Large Array (ngVLA) and the Square Kilometer Array…
Variable gamma-ray emission has been discovered in five Radio-loud Narrow Line Seyfert 1 (NLSy1) galaxies by the Large Area Telescope (LAT) onboard the Fermi Gamma-Ray Space Telescope. This has clearly demonstrated that these NLSy1 galaxies…
Blazars with redshifts z<0.1 are likely candidates for detection at energies in the range 300 GeV - 50 TeV with Cerenkov telescopes and scintillator arrays. We present gamma-ray flux predictions for a sample of 15 nearby flat-spectrum radio…
The VERITAS array of imaging atmospheric Cherenkov telescopes has collected nearly 6000 hours of observations of active galactic nuclei (AGNs). It has detected 39 very-high-energy (VHE, >100 GeV) AGNs at redshifts up to z = 0.9, of which 24…
Low Luminosity Active Galactic Nuclei (LLAGNs) possess the characteristic features of more luminous Active Galactic Nuclei (AGNs) but exhibit a much lower nuclear Halpha luminosity than their more luminous counterparts. M87 (NGC 4486) and…
The flat-spectrum radio quasar PKS 1441+25 at a redshift of z = 0.940 is detected between 40 and 250 GeV with a significance of 25.5 {\sigma} using the MAGIC telescopes. Together with the gravitationally lensed blazar QSO B0218+357 (z =…