Fabrizio Tavecchio — Page 8

arXiv2000

Constraints to the SSC model for Mkn 501

We fit the SEDs of the TeV blazar Mkn 501 adopting the homogeneous Synchrotron-Self Compton model to simultaneous X-ray and TeV spectra recently become available. We present detailed model spectra calculated with the above constraints and taking into account the absorption of TeV photons by the IR background. We found that the curved TeV spectra can be naturally reproduced even without IRB absorption. Taking IRB absorption into account changes the required parameter values only slightly.

astro-ph↗

arXiv1998

BeppoSAX Observations of the BL Lac Object Mkn 501 in an Intermediate State

The BL Lac object Mkn 501 was observed with the BeppoSAX satellite at three epochs in April-May 1998, simultaneously with the Whipple and HEGRA Cherenkov telescopes. The X-ray spectrum is well detected up to 70 keV and it exhibits, at all epochs, a continuous curvature, which is here modeled with three power-laws of increasingly steeper index at larger energies. In the nu*f_nu representation the spectrum exhibits a peak at ~20 keV, which is interpreted as the maximum of the synchrotron emission. This implies that the synchrotron peak energy has lowered by an order of magnitude with respect to the powerful X-ray outburst observed in April 1997. The simultaneous TeV flux was comparable to the lowest levels observed for Mkn 501, possibly suggesting that the peak of the inverse Compton radiation had also shifted toward lower energies.

astro-ph↗