Related papers: Physics Insights from Recent MAGIC AGN Observation…
Since the first TeV blazar Markarian (Mrk) 421 was detected in 1992, the number of established TeV gamma-ray emitting BL Lac objects has grown to 6, with redshifts ranging from 0.031 (Mrk 421) to 0.129 (H 1426+428). The intensive study of…
An anomalously large transparency of the Universe to gamma rays has recently been discovered by the Imaging Atmospheric Cherenkov Telescopes (IACTs) H.E.S.S. and MAGIC. We show that observations can be reconciled with standard blazar…
Context: MWC 656 has recently been established as the first observationally detected high-mass X-ray binary system containing a Be star and a black hole (BH). The system has been associated with a gamma-ray flaring event detected by the…
During remarkable flaring activity in 1997 Markarian 501 was the brightest source in the sky at TeV energies, outshining the Crab Nebula by a factor of up to 10. Periods of flaring activity each lasting a few days were observed…
Published EGRET spectra from blazars extend only to 10 GeV, yet EGRET has detected approximately 2000 gamma-rays above 10 GeV of which about half are at high Galactic latitude. We report a search of these high-energy gamma-rays for…
The radio galaxy NGC 1275, recently identified as a very high energy (VHE, >100 GeV) gamma-ray emitter by MAGIC, is one of the few non-blazar AGN detected in the VHE regime. In order to better understand the origin of the gamma-ray emission…
We describe the emission properties of blazars, i.e. the AGNs that, due to their peculiar orientation w.r.t. the observer, allow the most penetrating and direct view of their central engine. After showing that the extragalactic GeV-TeV sky…
Hints for a GeV component in the emission from GRBs are known since the EGRET observations during the '90s and they have been recently confirmed by the data of the Fermi satellite. These results have, however, shown that a fully…
Cosmic opacity for very high-energy gamma rays ($E>10$ TeV) due to the interaction with the extragalactic background light can be strongly reduced because of possible Lorentz-violating terms in the particle dispersion relations expected,…
The number of known very high energy (VHE) blazars is $\sim\,50$, which is very small in comparison to the number of blazars detected in other frequencies. This situation is a handicap for population studies of blazars, which emit about…
GRB 190114C is an unusual gamma-ray burst (GRB) due to its detection at sub-$TeV$ energies by MAGIC, seen at redshift z = 0.42. This burst is one of the brightest GRB detected by \fermi. A joint GBM-LAT analysis of the prompt emission…
Studies of radio galaxies at TeV energies are fascinating because their jets are misaligned concerning our sightline. Thus, it provides us with a unique opportunity to study the structure of their jets, the radiative processes, and the…
Context: Gamma-ray bursts are cosmological sources emitting radiation from the gamma-rays to the radio band. Substantial observational efforts have been devoted to the study of gamma-ray bursts during the prompt phase, i.e. the initial…
Line-like features in TeV $\gamma$-rays constitute a ''smoking gun'' for TeV-scale particle dark matter and new physics. Probing the Galactic Center region with ground-based Cherenkov telescopes enables the search for TeV spectral features…
Context. We present the discovery of very high energy (VHE, E > 100GeV) gamma-ray emission from the BL Lac object 1ES 1215+303 by the MAGIC telescopes and simultaneous multi-wavelength data in a broad energy range from radio to gamma-rays.…
The MAGIC collaboration has recently reported the discovery of gamma-ray emission from the binary system LS I +61 303 in the TeV energy region. Here we present new observational results on this source in the energy range between 300 GeV and…
Most $\gamma$-ray detected active galactic nuclei are blazars with one of their relativistic jets pointing towards the Earth. Only a few objects belong to the class of radio galaxies or misaligned blazars. Here, we investigate the nature of…
Milagro is a water Cherenkov extensive air shower array that continuously monitors the entire overhead sky in the TeV energy band. The results from an analysis of $\sim$3 years of data (December 2000 through November 2003) are presented.…
Recently, the Galactic Center has been reported to be a source of very high energy (VHE) gamma-rays by the VERITAS, CANGAROO and HESS experiments. The energy spectra as measured by these experiments show substantial differences. In this…
Active Galactic Nuclei (hereafter AGN) produce powerful outflows which offer excellent conditions for efficient particle acceleration in internal and external shocks, turbulence, and magnetic reconnection events. The jets as well as…