Related papers: Results on AGN observations with HEGRA
The radiation mechanism of very high energy $\gamma$-ray emission from blazars and crucial parameters like magnetic field, and size of the emitting region are not well understood yet. To understand the above mentioned properties of blazars,…
Recent highlight results obtained with the air shower detector complex HEGRA at the Canary island La Palma are presented. Observations and searches for gamma sources above an energy of 500 GeV are covered, where special emphasis is put on…
The HEGRA collaboration has achieved outstanding results during the operation of the six imaging atmospheric Cherenkov telescopes from 1996 to 2002. The experimental work pioneered the field of TeV gamma-ray astronomy with observations…
The HEGRA system of imaging air Cherenkov telescopes has successfully pioneered the stereoscopic observation technique of extensive air showers. The observational method is briefly described and important results of recent observations of…
The HEGRA experiment is an air shower detector system for the study of neutral and charged cosmic rays in the energy range between 500 GeV to 10 PeV. Here we give an overview of how the HEGRA detector is used to search for TeV…
In this paper, we present the results of Monte Carlo simulations of atmospheric showers induced by diffuse gamma rays as detected by the high-energy gamma ray astronomy (HEGRA) system of five imaging atmospheric Cerenkov telescopes (IACTs).…
A sample of 54 selected Active Galactic Nuclei (AGN) has been observed with the HEGRA stereoscopic system of Cherenkov Telescopes between 1996 and 2002 in the TeV energy regime. The observations were motivated by the positive results…
The recent advances in TeV gamma-ray astronomy are largely the result of the ability to differentiate between extensive air showers generated by gamma rays and hadronic cosmic rays. Air Cherenkov telescopes have developed and perfected the…
Milagro is a gamma-ray observatory employing a water Cherenkov detector to observe extensive air showers produced by high-energy particles impacting in the Earth's atmosphere. We discuss the first detection of TeV gamma-rays from the…
Since February 1997 the BL Lac object Mkn 501 is in a ``high state'' of gamma-ray emission. The HEGRA collaboration has studied Mkn 501 with their air Cherenkov telescopes on La Palma. Here we report on observations with the 5 m^2 telescope…
The HEGRA 5 m^2 air Cherenkov telescope (CT1) was used to search for gamma-ray emission above 1.5 TeV from a series of low redshift AGN (Mkn 421, Mkn 501, MS 0116+319, PKS 2209+236, NGC 315 and W Comae). Here we present results from a total…
In the recent years, the new generation of Imaging Atmospheric Cerenkov Telescopes successfully detected very high energy (VHE; E>100 GeV) gamma-ray emission from a growing number of Active Galactic Nuclei (AGNs), mainly belonging to the…
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$3 years of data (December 2000 through November 2003) are presented.…
The HEGRA system of 4 Imaging Atmospheric Cherenkov Telescopes (IACTs) has been used since March 1997 for a comprehensive study of the gamma-ray emission from the BL Lac object Mkn 501 in the energy range above 500 GeV. Taking advantage of…
A detection of Gamma-rays from Mkn 421 at energies above 1 TeV is reported, based on observations made in December 1994 - May 1995 with the first two HEGRA Cherenkov telescopes. >From the image analysis, 111 excess gamma candidates are…
The Milagro gamma-ray observatory employs a water Cherenkov detector to observe extensive air showers produced by high-energy particles impacting in the Earth's atmosphere. A 4800 m$^{2}$ pond instrumented with 723 8" PMTs detects Cherenkov…
The Hight Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory monitors the gamma-ray sky in the energy range from 100 GeV to 100 TeV and has detected two very high energy (VHE) blazars: Markarian 421 (Mrk 421) and Markarian 501 (Mrk 501)…
The High Altitude Water Cherenkov Gamma-Ray Observatory (HAWC) continuously detects TeV photons and particles within its large field-of-view, accumulating every day a deeper exposure of two thirds of the sky. We analyzed 1523~days of HAWC…
It is notoriously difficult to organize simultaneous observations from space and from the ground. This is particularly so at GeV-TeV energies where the space observations from all sky telescopes and the ground-based observations (mostly…
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. Depending on the magnetic fields in the vicinity of the…