The colliding-wind binary WR140: the particle acceleration laboratory

Abstract

WR+O star binary systems exhibit synchrotron emission arising from relativistic electrons accelerated where the wind of the WR star and that of its massive binary companion collide - the wind-collision region (WCR). These ``colliding-wind'' binaries (CWB), provide an excellent laboratory for the study of particle acceleration, with the same physical processes as observed in SNRs, but at much higher mass, photon and magnetic energy densities. WR140 is the best studied CWB, and high resolution radio observations permit a determination of several system parameters, particularly orbit inclination and distance, that are essential constraints for newly developed models of CWBs. We show a model fit to the radio data at orbital phase 0.9, and show how these models may be used to predict the high energy emission from WR140.