PHYSICS & STAR CLUSTER SEMINAR
X-Ray Binary Evolution:
The Effects of Self-Induced Irradiation
Jérȏme Quintin
Friday, April 26, 2013
11:30 a.m.
Johnson 120
Extensive grids of binary evolutionary tracks have been computed using the MESA code to study irradiated X-ray binary systems. Non-irradiated X-ray binaries have been well studied, but I will show how irradiation affects the evolution of low- and intermediate mass X-ray binaries and their long-term secular average properties. Since the donor star loses some of its mass to the neutron star, an accretion disk is formed around the neutron star and X-rays are emitted. Some of this radiation is intercepted by the donor star and this in turn modifies its physical properties. A model that includes the geometry of the binary system and a Monte-Carlo simulation to determine the penetration depth of X-rays has been developed. For instance, assuming an efficiency factor as low as 5% for the irradiation flux, the bloating of the donor star can lead to irradiation cycles in which mass transfer surpasses the Eddington limit. If irradiation is not considered, neutron stars can become as massive as 2.5 Msun. But if irradiation is included, they generally accrete less mass and their masses are often less than 2.0 Msun. Finally, the numerical results will be compared to the observed properties of binary millisecond pulsars.
