%0 Journal Article
%T Multiwavelength observations of Mkn 501 during the 1997 high state
%A D. Petry
%A M. Boettcher
%A V. Connaughton
%A A. Lahteenmaki
%A T. Pursimo
%A C. M. Raiteri
%A F. Schroeder
%A A. Sillanpaa
%A G. Sobrito
%A L. Takalo
%A H. Terasranta
%A G. Tosti
%A M. Villata
%J Physics
%D 2000
%I arXiv
%R 10.1086/308955
%X During the observation period 1997, the nearby Blazar Mkn 501 showed extremely strong emission and high variability. We examine multiwavelength aspects of this event using radio, optical, soft and hard X-ray and TeV data. We concentrate on the medium-timescale variability of the broadband spectra, averaged over weekly intervals. We confirm the previously found correlation between soft and hard X-ray emission and the emission at TeV energies, while the source shows only minor variability at radio and optical wavelengths. The non-linear correlation between hard X-ray and TeV fluxes is consistent with a simple analytic estimate based on an SSC model in which Klein-Nishina effects are important for the highest-energy electrons in the jet, and flux variations are caused by variations of the electron density and/or the spectral index of the electron injection spectrum. The time-averaged spectra are fitted with a Synchrotron Self-Compton (SSC) dominated leptonic jet model, using the full Klein-Nishina cross section and following the self-consistent evolution of relativistic particles along the jet, accounting for gamma-gamma absorption and pair production within the source as well as due to the intergalactic infrared background radiation. The contribution from external inverse-Compton scattering is tightly constrained by the low maximum EGRET flux and found to be negligible at TeV energies. We find that high levels of the X-ray and TeV fluxes can be explained by a hardening of the energy spectra of electrons injected at the base of the jet, in remarkable contrast to the trend found for gamma-ray flares of the flat-spectrum radio quasar PKS 0528+134.
%U http://arxiv.org/abs/astro-ph/0002255v1