Exploring the Nature of the Brightest Hyper-luminous X-ray Source

Abstract

The small subset of hyper-luminous X-ray sources with luminosities in excess of ~1E41 erg/s are hard to explain without the presence of an intermediate mass black hole, as significantly super-Eddington accretion and/or very small beaming angles are required. The recent discovery of HLX-1, the most luminous object in this class with a record breaking luminosity of ~1E42 erg/s in the galaxy ESO 243-49, therefore currently provides some of the strongest evidence for the existence of intermediate mass black holes. HLX-1 is almost an order of magnitude brighter than the other hyper-luminous sources, and appears to exhibit X-ray spectral and flux variability similar to Galactic stellar mass black hole X-ray binaries. In this paper we review the current state of knowledge on this intriguing source and outline the results of multi-wavelength studies from radio to ultra-violet wavelengths, including imaging and spectroscopy of the recently identified optical counterpart obtained with the Very Large Telescope. These results continue to support an intermediate mass black hole in excess of 500 Msun

6 pages, 6 figures. Accepted for publication in the Astronomische Nachrichten, to appear in the proceedings of the conference "Ultra-Luminous X-ray sources and Middle Weight Black Holes" (Madrid, May 24-26, 2010)

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Cited by in corpus (12)

• The most extreme ultraluminous X-ray sources: evidence for intermediate-mass black holes?
• X-ray Variability and Hardness of ESO 243-49 HLX-1: Clear Evidence for Spectral State Transitions
• The origin of variability of the intermediate-mass black-hole ULX system HLX-1 in ESO 243-49
• The Close Stellar Companions to Intermediate Mass Black Holes
• A Young Massive Stellar Population Around the Intermediate Mass Black Hole ESO 243-49 HLX-1
• Nature of the Extreme Ultraluminous X-ray Sources
• Ultra-Luminous X-ray Sources in Haro 11 and the Role of X-ray Binaries in Feedback in Lyman-alpha Emitting Galaxies
• Combined Analysis of Hubble and VLT Photometry of the Intermediate Mass Black Hole ESO 243-49 HLX-1
• NIR Counterparts to ULXs (III): Completing the photometric survey and selected spectroscopic results
• Understanding the environment around the intermediate mass black hole candidate ESO 243-49 HLX-1
• Discovery and analysis of a ULX nebula in NGC 3521
• Exploring the nature of ultra-luminous X-ray sources across stellar population ages using detailed binary evolution calculations