High Mass X-ray Binaries: Future Evolution and Fate
  BH-NS and BH-BH systems are among the most promising gravitational wave sources detectable by advanced LIGO/VIRGO and the Einstein Telescope. Although the rates of these systems may be above those of NS-NS mergers, BH-NS and BH-BH systems are difficult to detect, and thusfar none have been observed. But the progenitors of BH-NS and BH-BH binary systems may have been observed, in the form of High-Mass X-ray Binaries (HMXBs). In this paper, we continue work studying these potential progenitors of these important gravitational wave sources. In the first two papers of the series, we have demonstrated that IC10 X-1 and NGC300 X-1 are direct progenitors of BH-BH systems and that Cyg X-1 may form, alas with a very low probability, a BH-NS system. Here, we analyze the Galactic binaries GX 301-2, Vela X-1, XTEJ1855-026, 4U1907+09, Cir X-1 and extra-galactic LMC X-1, LMC X-3, M33 X-1. In each case, we find that the future evolution will not allow the formation of a BH-NS nor a BH-BH system. Most of these binaries will soon merge in the common envelope phase, with a compact object sinking into a helium-rich core of a stellar companion. This "helium-merger" may be a progenitor for long duration gamma-ray bursts (GRBs). Based on the observed HMXB population, the rate of helium-mergers may make up a sizable fraction of long-duration GRBs. Due to this high number of potential GRB progenitors, a chance that a Galactic HMXB has caused one of the recent major mass extinction events is significant (10-20%). 
Krzysztof Belczynski (Warsaw/UTB), Tomasz Bulik (Warsaw), Chris L.   Fryer (LANL)
astro-ph.HE astro-ph.GA