Colliding winds in ultraluminous X-ray sources

Abstract

Ultraluminous X-ray sources (ULX) are objects with luminosities that exceed the Eddington limitfor a stellar-mass black hole. In these closed binary systems, the star overflows its Roche lobe and the black holeaccretes matter at a supercritical rate. The upper layers of the disk are no longer in equilibrium and are ejectedas a powerful radiation-driven wind that interacts with the wind from the star producing shocks where particlescan be accelerated up to relativistic energies and then cool down yielding a broadband spectrum