Ultraluminous X-Ray Sources in External Galaxies
Top Cited Papers
Open Access
- 10 May 2001
- journal article
- research article
- Published by American Astronomical Society in The Astrophysical Journal
- Vol. 552 (2) , L109-L112
- https://doi.org/10.1086/320343
Abstract
We investigate models for the class of ultraluminous nonnuclear X-ray sources (i.e., ultraluminous compact X-ray sources [ULXs]) seen in a number of galaxies and probably associated with star-forming regions. Models in which the X-ray emission is assumed to be isotropic run into several difficulties. In particular, the formation of sufficient numbers of the required ultramassive black hole X-ray binaries is problematic, and the likely transient behavior of the resulting systems is not in good accord with observation. The assumption of mild X-ray beaming suggests instead that ULXs may represent a short-lived but extremely common stage in the evolution of a wide class of X-ray binaries. The best candidate for this is the phase of thermal-timescale mass transfer that is inevitable in many intermediate- and high-mass X-ray binaries. This in turn suggests a link with the Galactic microquasars. The short lifetimes of high-mass X-ray binaries would explain the association of ULXs with episodes of star formation. These considerations still allow the possibility that individual ULXs may contain extremely massive black holes.Keywords
All Related Versions
This publication has 30 references indexed in Scilit:
- On the Stability of Very Massive Primordial StarsThe Astrophysical Journal, 2001
- Chandra High-Resolution Camera observations of the luminous X-ray source in the starburst galaxy M82Monthly Notices of the Royal Astronomical Society, 2001
- The population of faint transients in the Galactic CentreMonthly Notices of the Royal Astronomical Society, 2000
- Radiatively Driven Outflows and Avoidance of Common-Envelope Evolution in Close BinariesThe Astrophysical Journal, 1999
- A 106 Day Period in the Nuclear Source X-8 in M33The Astrophysical Journal, 1997
- A Unified Model for the Spectral Variability in GRS 1915+105The Astrophysical Journal, 1997
- A Search for “Dwarf” Seyfert Nuclei. IV. Nuclei with Broad Hα EmissionThe Astrophysical Journal Supplement Series, 1997
- Formation of Low-Mass X-Ray Binaries. I. Constraints on Hydrogen-rich Donors at the Onset of the X-Ray PhaseThe Astrophysical Journal, 1996
- X Rays From Normal GalaxiesAnnual Review of Astronomy and Astrophysics, 1989
- Thick accretion disks with super-Eddington luminositiesThe Astrophysical Journal, 1980