2008/06/13 by Yungelson, L. R., Lasota, J. -P.
#Astrophysics (astro-ph) #FOS: Physical sciences
paper · doi:10.48550/arxiv.0806.2235
We discuss the formation, evolution and observational parameters of the population of short-period (<10 hr) low-mass black-hole binaries (LMBHB). Their evolution is determined by the orbital angular momentum loss and/or nuclear evolution of the donors. All observed semidetached LMBHB are observed as soft X-ray transients (SXTs). The absence of observed short-period stable luminous X-ray sources with black holes and low-mass optical components suggests that upon RLOF by the donor, the angular-momentum losses are substantially reduced. The model with reduced angular-momentum loss reasonably well reproduces the masses and effective temperatures of the observed secondaries of SXTs. Theoretical mass-transfer rates in SXTs are consistent with those deduced from observations only if the accretion discs in LMBHB are truncated. The population of short-period LMBHB is formed mainly by systems which at RLOF had unevolved or slightly evolved donors (abundance of hydrogen in the center > 0.35). Our models suggest that a very high efficiency of common envelopes ejection is necessary to form LMBHB.