High-energy radiation generated by winds and shocks: SNRs and superbubbles

Abstract

We discuss populations of X-ray and $\gamma$-ray sources in star-forming regions (SFR). Interacting winds of massive stars and high supernova activity in SFRs can be powerful sources of high energy emission. Models of nonthermal particle acceleration in the vicinity of active SFRs are reviewed. A class of hard emission sources where a fast wind from a massive star collides with a supernova shell is described. Stellar winds of massive stars and core collapsed supernova explosions with great energy release in the form of multiple interacting shock waves inside the superbubbles are argued as favorable sites of nonthermal particle acceleration. Young stellar objects and supernova activity in the dense environment of starforming regions produce an another potentially abundant class of hard faint X-ray sources due to interaction of fast moving knots with the dense ambient medium. The knots could have very different physical nature, e.g. supernova ejecta fragments or Herbig-Haro-like objects. We argue that the sources may have rather steep logN—logS distribution and can contribute substantially to the galactic diffuse emission including the both low-ionized 6.4 keV and He-like Fe lines.