Editor's Summary
2 July 2009
A mid-sized black hole
There should be some intermediate-mass black holes out there, in the gap between the stellar mass and super-massive populations. Too large to have formed by the collapse of a massive star, but too small to be found at the centre of galaxies, they are thought to form in dense stellar clusters or globular clusters. Until now there was no strong observational evidence for their existence. But the 'missing link' of the black hole world may have now been found with the discovery of a variable ultraluminous X-ray source, in the edge-on spiral galaxy ESO 243–49. The extreme luminosity of the source — HLX-1 for short — is consistent with the presence of an intermediate-mass black hole of over 500 solar masses.
Letter: An intermediate-mass black hole of over 500 solar masses in the galaxy ESO 243-49
Sean A. Farrell, Natalie A. Webb, Didier Barret, Olivier Godet & Joana M. Rodrigues
doi:10.1038/nature08083
