Classifying the Zoo of Ultraluminous X-ray Sources

Roberto Soria, Mark Cropper, Christian Motch
2005 Chinese Journal of Astronomy and Astrophysics  
Ultraluminous X-ray sources (ULXs) are likely to include different physical types of objects. We discuss some possible subclasses, reviewing the properties of a sample of ULXs recently observed by Chandra and XMM-Newton. Sources with an isotropic X-ray luminosity up to a few times 10 39 erg s −1 are consistent with "normal" stellar-mass X-ray binaries (mostly high-mass X-ray binaries in star-forming regions). Higher black hole (BH) masses (≈ 50-100M ⊙ ) may be the end product of massive stellar
more » ... evolution in peculiar environments: they may explain ULXs with luminosities ≈ 1-2 × 10 40 erg s −1 . Only a handful of ULXs require a true intermediate-mass BH (M > ∼ 500M ⊙ ). Finally, a small subclass of ULXs shows flaring or rapid variability in its power-law spectral component.
doi:10.1088/1009-9271/5/s1/153 fatcat:jjeph7sd45dx5o2gktfxyemveu