924 citations · 39.2k across the 592 of their papers we have counts for
16 papers · 1 filter
Search for a TeV gamma-ray halo of Mkn 501
HEGRA Collaboration, F. Aharonian
For distant extragalactic sources of gamma-rays in the PeV energy range, interactions of the gamma rays with intergalactic diffuse radiation fields will initiate a pair cascade. De…
Gamma Rays from Molecular Clouds
F. A. Aharonian
I discuss the spectral features of pi-0 decay gamma-radiation from clouds/targets located in proximity of relatively young proton accelerators, and speculate that such ``accelerato…
Reanalysis of the high energy cutoff of the 1997 Mkn 501 TeV energy spectrum
HEGRA Collaboration, F. Aharonian
Data taken with the HEGRA system of imaging atmospheric Cherenkov telescopes during the 1997 flares of Mkn 501 are reanalyzed using an algorithm providing improved energy resolutio…
Complex Spectral Variability from Intensive Multi-wavelength Monitoring of Mrk421 in 1998
T. Takahashi, J. Kataoka, G. Madejski +20
We conducted a multi-frequency campaign for the TeV blazar Mrk~421 in 1998 April. The campaign started from a pronounced high amplitude flare recorded by SAX and Whipple; ASCA obse…
The TeV Energy Spectrum of Mkn 501 Measured with the Stereoscopic Telescope System of HEGRA during 1998 and 1999
The HEGRA Collaboration, F. Aharonian, A. Akhperjanian +1
During 1997, the BL Lac object Mkn 501 went into an extraordinary state of high X-ray and TeV gamma-ray activity, lasting more than 6 months. In this paper we report on the TeV emi…
Optimizing the angular resolution of the HEGRA telescope system to study the emission region of VHE gamma rays in the Crab Nebula
HEGRA Collaboration, F. Aharonian
The HEGRA system of imaging atmospheric Cherenkov telescopes provides for specially selected classes of events an angular resolution of better than 3'. By comparing the measured an…
BeppoSAX Observations of Markarian 501 in June 1999
E. Pian, L. Chiappetti, P. Giommi +19
We present the preliminary results of a long BeppoSAX observation of the BL Lac object Mkn501 carried out in June 1999. The source was fainter than found during the BeppoSAX pointi…
5@5 - a 5 GeV energy threshold array of imaging atmospheric Cherenkov telescopes at 5 km altitude
F. A. Aharonian, A. K. Konopelko, H. J. Voelk +1
We discuss the concept and the performance of a powerful future ground-based astronomical instrument - a stereoscopic array of several large imaging atmospheric Cherenkov telescope…
Rejection of the hypothesis that Markarian 501 TeV photons are pure Bose-Einstein condensates
The HEGRA Collaboration, F. Aharonian, A. Akhperjanian +1
The energy spectrum of the Blazar type galaxy Markarian 501 (Mrk 501) as measured by the High-Energy-Gamma-Ray Astronomy (HEGRA) air Cerenkov telescopes extends beyond 16 TeV and c…
Constraints on the Cosmic Infra-Red Background based on BeppoSAX and CAT spectra of Mkn 501
J. Guy, C. Renault, F. A. Aharonian +2
The TeV and X-ray data obtained by the imaging Cherenkov telescope CAT and X-ray satellite BeppoSAX during the remarkable flare of Mkn 501 in April 16, 1997 are used to constrain t…
The Energy Spectrum of TeV Gamma-Rays from the Crab Nebula as measured by the HEGRA system of imaging air Cherenkov telescopes
F. Aharonian, The HEGRA Collaboration
The Crab Nebula has been observed by the HEGRA (High-Energy Gamma-Ray Astronomy) stereoscopic system of imaging air Cherenkov telescopes (IACTs) for a total of about 200 hrs during…
Very-high-energy gamma radiation associated with the unshocked wind of the Crab pulsar
S. V. Bogovalov, F. A. Aharonian
We show that the relativistic wind in the Crab pulsar, which is commonly thought to be invisible in the region upstream of the termination shock at R < 0.1 pc, in fact could be dir…
TeV Gamma Rays from BL Lac Objects due to Synchrotron Radiation of Extremely High Energy Protons
F. A. Aharonian
One of remarkable features of the gamma ray blazar Markarian 501 is the reported shape of the TeV spectrum, which during strong flares of the source remains essentially stable desp…
Correlated intense X-ray and TeV activity of Mrk~501 in 1998 June
Rita M. Sambruna
We present exactly simultaneous X-ray and TeV monitoring with {\it RXTE} and HEGRA of the TeV blazar Mrk 501 during 15 days in 1998 June. After an initial period of very low flux a…
On energy-dependent propagation effects and acceleration sites of relativistic electrons in Cassiopeia A
A. M. Atoyan, R. J. Tuffs, F. A. Aharonian +1
We consider the effect of energy dependent propagation of relativistic electrons in a spatially inhomogeneous medium in order to interpret the broad-band nonthermal radiation of th…
On the gamma-ray fluxes expected from Cassiopeia A
A. M. Atoyan, F. A. Aharonian, R. J. Tuffs +1
Based on the results of our previous study of the broad band synchrotron emission of Cas A in the framework of a spatial inhomogeneous model, we calculate the fluxes of gamma-radia…