Gamma-ray emission from Wolf-Rayet binaries

P. BENAGLIA; G. E. ROMERO

ASTRONOMY AND ASTROPHYSICS

EDP Sciences

Lugar: Les Ulis Cedex A; Año: 2003 vol. 399 p. 1121 - 1134

0004-6361

Abstract. In the colliding wind region of early-type binaries, electrons can be accelerated up to relativistic energies displaying power-law spectra, as demonstrated by the detection of non-thermal radio emission from severalWR+OB systems. The particle acceleration region, located between the stars, is exposed to strong photon fields in such a way that inverse Compton cooling of the electrons could result in a substantial high-energy non-thermal flux. In particular cases, the ratio of the energy densities of magnetic to photon fields in the colliding wind region will determine whether a given source can produce or not significant gamma-ray emission. We present here a study of the binaries WR 140, WR 146, and WR 147 in the light of recent radio and gamma-ray observations. We show that with reasonable assumptions for the magnetic field strength WR 140 can produce the gamma-ray flux from the EGRET source 3EG J2022+4317. WR 146 and WR 147 are below the detection threshold, but new and forthcoming instruments like INTEGRAL and GLAST might detect non-thermal emission from them.