Ultraluminous X-ray Sources
Abstract
Ultraluminous X-ray sources (ULXs) represent a class of binary systems that are more luminous than any black hole in our Galaxy. The nature of these objects remained unclear for a long time. The most popular models for the ULXs involve either intermediate mass black holes (IMBHs) or stellar-mass black holes accreting at super-Eddington rates. In the last few years our understating of these objects was significantly improved, which made the model of super-Eddington accretion much preferable. Both the X-ray and optical spectra provide evidence for the strong outflows coming from supercritical accretion disk. Another surprising result was discovery of pulsations in four ULXs, which claims that these systems must host neutron stars. Besides the presence of pulsations, there is no sharp difference between ultraluminous pulsars and normal ULXs. This fact implies that significant number of known ULXs might eventually be neutron stars.
- Publication:
-
Accretion Processes in Cosmic Sources - II
- Pub Date:
- September 2018
- DOI:
- 10.22323/1.342.0038
- arXiv:
- arXiv:1812.02516
- Bibcode:
- 2018acps.confE..38A
- Keywords:
-
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 11 pages, 1 figure. Submitted to Proceedings of Science ("APCS2018: Accretion Processes in Cosmic Sources -- II" held at S. Petersburg, Ed. Franco Giovannelli)