Formation and Evolution of Microquasar GRS 1915+105

Abstract

Using the StarTrack population synthesis code we analyze the possible formation channels of the Galactic microquasar GRS 1915+105 harboring the most massive known stellar black hole. We find that we are able to reproduce the evolution and the current state of GRS 1915+105 in a model with lowered wind mass loss rates in massive stars. We conclude that the existence of GRS 1915+105 implies that stellar winds in massive stars are a factor of two weaker, but still within observational bounds, than used in stellar models. We discuss the mass transfer initiated by the massive primary in binaries which are the possible precursors of systems harboring massive black holes. We show that such mass transfer evolution is neither clear case B nor C, but instead is initiated during the core helium burning phase of the massive donor star, the progenitor of the black hole. We also argue that massive black holes do not receive any kicks at their formation and are formed through direct collapse of progenitor star without accompanying supernova explosion.