EDP Sciences
Free access
Volume 393, Number 3, October III 2002
Page(s) L61 - L64
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:20021205

A&A 393, L61-L64 (2002)
DOI: 10.1051/0004-6361:20021205


Recurrent microblazar activity in Cygnus X-1?

G. E. Romero1, 2, M. M. Kaufman Bernadó1 and I. F. Mirabel2, 3

1  Instituto Argentino de Radioastronomía, C.C.5, (1894) Villa Elisa, Buenos Aires, Argentina
2  CEA/DMS/DAPNIA/Service d'Astrophysique, Centre d'Études de Saclay, 91191 Gif-sur-Yvette, France
3  Instituto de Astronomía y Física del Espacio/CONICET, C.C. 67, Suc. 28, Buenos Aires, Argentina

(Received 11 July 2002 / Accepted 20 August 2002)

Recurrent flaring events at X- and soft gamma-ray energies have been recently reported for the galactic black hole candidate Cygnus X-1. The observed fluxes during these transient outbursts are far higher than what is observed in "normal" episodes. Here we suggest that the origin of this radiation is non-thermal and produced by inverse Compton interactions between relativistic electrons in the jet and external photon fields, with a dominant contribution from the companion star field. The recurrent and relatively rapid variability could be explained by the precession of the jet, which results in a variable Doppler amplification.

Key words: X-ray binaries -- stars: individual: Cyg X-1 -- gamma-rays: observations -- gamma-rays: theory

Offprint request: G. E. Romero, romero@venus.fisica.unlp.edu.ar

© ESO 2002