Resumo

CHRISTIANSEN, Hugo R.; ROMERO, Gustavo E.  e  ORELLANA, Mariana. High-energy gamma-ray production in microquasars. Braz. J. Phys. [online]. 2007, vol.37, n.2b, pp. 545-548. ISSN 0103-9733.  http://dx.doi.org/10.1590/S0103-97332007000400012.

A hadronic model for gamma-ray production in microquasars is presented. Microquasars are galactic binary systems with jets, which have, presumably, hadronic components. We consider a microquasar formed by a neutron star that accretes matter from the equatorial wind of a Be primary star. The collision between the jet, emitted by the compact object, and the dense equatorial disk of the companion massive star is responsible for the gamma-ray production. Gamma-rays result from the decay of neutral pions produced in relativistic pp interactions arising from this collision all along the orbit. Assuming a simple, positional independent set of parameters, our calculations are consistent with a peak of gamma-ray flux at the periastron passage with a secondary maximum near apastron. Under this assumption, gamma-ray signals would be in contrast with the radio/X-ray outbursts which peak clearly after periastron. We finally calculate the opacity of the ambient photon field to the propagation of the gamma-rays. The spectral energy distribution appears strongly attenuated in a wide band (50 GeV - 50 TeV) due to local absorption. These spectral features should be detectable by an instrument like MAGIC through exposures integrated along several periastron passages.

Palavras-chave : Galactic gamma-rays sources.