X-ray and gamma-ray emission from jets in black-hole binaries. Cyg X-3 and Cyg X-1
Cyg X-3 is the only accreting binary from which high-energy gamma-rays have been unambiguously detected. The gamma-ray spectrum observed by Fermi together with the contemporaneous X-ray spectrum imply the presence of a low-energy cutoff in the distribution of accelerated electrons at a Lorentz factor of ~1000, which agrees with recent shock acceleration models. The jet kinetic power is estimated to be about 10^38 erg/s. (Zdziarski et al. arXiv:1111.0878v1).
We critically analyze the recent claim of Laurent et al. (2011Sci...332..438L) of a strongly polarized power-law tail extending to 2 MeV in the spectrum of Cyg X-1, which would imply the presence of a jet synchrotron component. We calculate the actual spectrum in that region, find it to be an order of magnitude lower, and compatible with Comptonization in the accretion flow.
Last updated on 20.10.2012 11:17