2002/09/22 by D. Horns, Horns, D., the HEGRA collaboration +1
Engineering · Physics and Astronomy · #Astrophysics (astro-ph) #Astrophysics and Cosmic Phenomena #Dark Matter and Cosmic Phenomena #FOS: Physical sciences #Particle Accelerators and Free-Electron Lasers #Particle physics theoretical and experimental studies #Solar and Space Plasma Dynamics #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0209454
6 pages, 4 figures, will appear in the Proceedings for "High Energy Blazar astronomy", Turku, Finland 2002
arxiv created 2002/09/22 · openalex publication_date 2002/09/22 · arxiv updated 2009/12/01 · openalex created_date 2019/06/27 · openalex updated_date 2026/07/28
Recent results obtained with the HEGRA system of imaging Cherenkov telescopes\non the TeV emission of the Blazars Mkn~421 (z=0.030), 1ES1959+650\n(z=0.047), and H1426+428 (z=0.129) are reported. For Mkn~421, a close\nconnection of the average flux level and spectral shape has been observed\nduring the periods of increased activity in the years 2000 and 2001.\nSimultaneously taken data with the RXTE X-ray satellite reveal a complex light\ncurve at X-ray and TeV energies. After a deep exposure of 94 hrs, the object\n1ES1959+650 was detected at the significance level of 5.4\σ with a soft\nenergy spectrum following a power-law with a photon-index of 3.3 \± 0.7.\nDuring recent observations in May 2002, the source has shown increased activity\nwith indications for a flattening of the energy spectrum.\n The high energy peaked Blazar H1426+428 has recently been identified as a\nsource of TeV photons. Since the source is fairly distant (z=0.129), absorption\nof TeV photons due to pair-production on the optical and near infrared\nextragalactic light becomes important and should leave a signature in the\nobserved TeV energy spectrum. Notably, the TeV energy spectrum determined with\nthe HEGRA system of Cherenkov telescopes agrees with the expectation of a\nstrongly absorbed source spectrum.\n