X-Ray Binaries

1. Tim Linden, Vicky Kalogera, Jeremy Sepinsky, Andrea Prestwich, Andreas Zezas, Jay Gallagher
2. 1005.1639

Low Metallicity Environments Produce a Brighter High-Mass X-Ray Binary Population

We study the effects of binary evolution on the production and emission of high-mass x-ray binaries. We find that there are two separate methods to produce extremely bright x-ray binary activity. The first is active primarily in high-metallicity environments, and is powered by the strong winds of supergiant OB stars which efficiently push material onto their binary companion. The second is active primarily in low-metallicity environemnts, as is powered by the production of tight binary orbits with efficient Roche Lobe Overflow producing mass transfer onto the compact object. The dominance of Roche Lobe Overflow at low metallicities is due to the small size of early-stage stars which allows binaries with small periods to form efficiently. The net effect is that more bright x-ray binaries are formed at low metallicities, increasing the x-ray luminosity of metal poor galaxies.