Open AccessThe population of faint transients in the Galactic Centre
Author(s) -
King A. R.
Publication year - 2000
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2000.03644.x
Subject(s) - physics , astrophysics , neutron star , galaxy , population , astronomy , black hole (networking) , low mass , transient (computer programming) , stars , computer network , routing protocol , demography , routing (electronic design automation) , sociology , computer science , link state routing protocol , operating system
BeppoSAX has detected a population of faint transient X‐ray sources in the Galactic Centre. I show that a simple irradiated disc picture gives a consistent fit to the properties of this population, and that it probably consists of low‐mass X‐ray binaries (LMXBs) that have evolved beyond their minimum orbital periods of ∼80 min. Since all post‐minimum systems are transient, and neutron star LMXBs are more common than black hole LMXBs in the Galaxy, the majority of these systems should contain neutron stars, as observed. This picture predicts that the Galactic Centre transients should have orbital periods in the range ∼80–120 min, and that most of them should repeat in the next few years. In this case, the total number of post‐minimum transients in the Galaxy would be considerably smaller than the usual estimates of its total LMXB population. I discuss possible reasons for this.