2017ApJ...846...17W -
Astrophys. J., 846, 17-17 (2017/September-1)
The origin of the ultraluminous X-ray sources.
WIKTOROWICZ G., SOBOLEWSKA M., LASOTA J.-P. and BELCZYNSKI K.
Abstract (from CDS):
Recently, several ultraluminous X-ray (ULX) sources were shown to host a neutron star (NS) accretor. We perform a suite of evolutionary calculations, which show that, in fact, NSs are the dominant type of ULX accretor. Although black holes (BH) dominate early epochs after the star-formation burst, NSs outweigh them after a few 100 Myr and may appear as late as a few gigayears after the end of the star-formation episode. If star formation is a prolonged and continuous event (i.e., not a relatively short burst), NS accretors dominate the ULX population at any time in the solar metallicity environment, whereas BH accretors dominate when the metallicity is sub-solar. Our results show a very clear (and testable) relation between the companion/donor evolutionary stage and the age of the system. A typical NSULX consists of a ∼1.3 M☉ NS and ∼1.0 M☉ Red Giant. A typical BH ULX consists of a ∼8 M☉ BH and ∼6 M☉ main-sequence star. Additionally, we find that the very luminous ULXs (LX 1041 erg s–1) are predominantly BH systems (∼9 M☉) with Hertzsprung-gap donors (∼2 M☉). Nevertheless, some NSULX systems may also reach extremely high X-ray luminosities (>=1041 erg s–1).
Abstract Copyright:
© 2017. The American Astronomical Society. All rights reserved.
Journal keyword(s):
methods: statistical - stars: black holes - stars: neutron - X-rays: binaries - X-rays: binaries
Simbad objects:
8
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