Speaker
Description
Ultraluminous X-ray sources (ULXs) are off-nuclear objects with apparent luminosities exceeding the Eddington limit for accreting stellar-mass black holes. Past this limit, radiation pressure dominates gravity, and the excess supply of matter would be ejected. To explain such high luminosities, the source emission is thought to be strongly collimated by the radiatively driven winds. Certain Galactic X-ray sources, such as SS 433 and Cygnus X-3, are suspected to be concealed ULXs viewed edge-on.
To better understand the observable properties of concealed super-Eddington accreting objects, we have made simulations of polarized scattering in the wind. We find that the collimation is less efficient than in purely geometrical models. Our model is capable of explaining the observed polarization degree variations in Cygnus X-3 and places constraints on the physical properties of the wind. Further development of the model should elucidate the connection between Galactic sources and face-on ULXs.