CAT VHE γ-ray observations of Mkn 501 and Mkn 421, and implications on the blazar phenomenon

Djannati-Ataı¨ for the CAT collaboration, Arache
April 2000
AIP Conference Proceedings;2000, Vol. 510 Issue 1, p328
Academic Journal
Two blazars, Mrk421 and Mrk501, have been detected at TeV energies by the CAT telescope operating in the French Pyrene´es. The Very High Energy (VHE) emission observed from Mrk501 exhibits dramatically different behavior in the quiescent and flaring states: the steep power-law spectrum seen in the low-activity state of 1998 contrasting with the harder, curved spectrum in the high-activity state of 1997. Mrk421 observations, on the other hand, are consistent with a power-law spectrum from the low-to-midrange intensities seen in 1998. The VHE spectra, considered along with the low-energy (X-ray) behavior of these sources, shed light on gamma-ray production and absorption mechanisms within blazar jets. © 2000 American Institute of Physics.


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