2001/08/22 by A. R. King, King, A. R.
Physics and Astronomy · #Astrophysics (astro-ph) #FOS: Physical sciences #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0108364
5 pages, no figures; to appear in the Proceedings of the Jan van Paradijs Memorial Symposium, Amsterdam, June 2001
arxiv created 2001/08/22 · arxiv updated 2009/12/01
I briefly review the theory of soft X-ray transient systems. Irradiation of the accretion disc faces by the central X-ray source determines both the occurrence and the nature of the outbursts, in particular forcing these to be long viscous events and producing exponential decays at short orbital periods. Soft X-ray transients constitute the majority of LMXBs, persistent systems being largely confined to a subset of neutron-star LMXBs with periods P < 2 d. It appears that LMXBs very frequently contain nuclear-evolved companions, even at short orbital periods. In long-period transients (P > 20 d) the outburst recurrence times must become extremely long (> 1500 yr). The outbursts are highly super-Eddington, markedly reducing the accretion efficiency. Spinup of a neutron-star primary to millisecond periods probably cannot occur for orbital periods > 200 d, in agreement with observations of binary pulsars.