Particle acceleration in colliding-wind massive binaries: a relevant science case for ASTRO-H

The strong stellar winds of massive stars in binary systems interact through shocks responsible for several phenomena, including significant particle acceleration up to relativistic energies. The existence of this relativistic particle population is mainly revealed through detection of bright synchrotron radio emission in the case of a few tens of systems. More recently, Suzaku observations revealed the existence of non-thermal X-rays in the case of two colliding-wind binaries (CWBs), confirming the prediction that inverse Compton scattering should be at
work in these objects. In this context, the ASTRO-H mission constitutes the ideal tool to investigate non-thermal phenomena in hard X-rays (above 10 keV), where the well-known thermal emission from the shocked winds should not be significantly present. This poster gives an overview of this science case, and provides clues for the expected input of ASTRO-H in the study of these objects.