Centrum Astronomii
Uniwersytet Mikołaja Kopernika

X-ray and gamma-ray emission from jets in black-hole binaries. Cyg X-3 and Cyg X-1

prof. dr hab Andrzej Zdziarski (CAMK PAN Warszawa)

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.

Data
21.11.2011 - 11:15
Miejsce
Sala seminaryjna KRA