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Particle acceleration and synchrotron emission in Mrk 501
Author(s) -
Wagner S.J.,
Lamer G.,
Bicknell G.V.
Publication year - 1999
Publication title -
astronomische nachrichten
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.394
H-Index - 63
eISSN - 1521-3994
pISSN - 0004-6337
DOI - 10.1002/1521-3994(199908)320:4/5<226::aid-asna226>3.0.co;2-#
Subject(s) - synchrotron , physics , particle acceleration , acceleration , astrophysics , astronomy , optics , classical mechanics
Abstract Mrk 501 became very active in 1997. The cut‐off frequency of the synchrotron emission increased by two orders of magnitude during an extensive flare, lasting several months. The increase in hard X‐ray flux is accompanied by an increase in TeV emission. We have carried out several multi‐frequency campaigns in 1997 and 1998, involving observations of the X‐ray spectrum with SAX and XTE, as well as low‐frequency monitoring during epochs of intense TeV observations. Here we report on a campaign carried out in July 1997. We find the X‐ray spectra to be composed of several components with very different cut‐off energies and different variability patterns. We model the variation of the synchrotron spectra with several components, the evolution of which is tightly constrained by the wide‐band coverage of the SED and the dense temporal coverage. The temporal characteristics indicate that acceleration time‐scales are short but longer than cooling time‐scales throughout the entire regime of photon energies covered in this study. We will present a consistent modeling of the synchrotron spectra up to the highest energies and provide important constraints on the acceleration mechanisms.