SCYON Abstract

Received on January 27 2007

A black hole in a globular cluster

AuthorsThomas J. Maccarone (1), Arunav Kundu (2), Stephen E. Zepf (2), and Katherine L. Rhode (3,4)
Affiliation
(1) School of Physics and Astronomy, University of Southampton
(2) Department of Physics and Astronomy, Michigan State University
(3) Astronomy Department, Wesleyan University
(4) Astronomy Department, Yale University
To appear inNature
Contacttjm@phys.soton.ac.uk
URLhttp://dx.doi.org/10.1038/nature05434
Links

Abstract

Globular star clusters contain thousands to millions of old stars packed within a region only tens of light years across. Their high stellar densities make it very probable that their member stars will interact or collide. There has been considerable debate about whether black holes should exist in these star clusters. Some theoretical work suggests that dynamical processes in the densest inner regions of globular clusters may lead to the formation of black holes of ∼1,000 solar masses. Other numerical simulations instead predict that stellar interactions will eject most or all black holes that form in globular clusters. Here we report the X-ray signature of an accreting black hole in a spectroscopically-confirmed globular cluster in the Virgo Cluster giant elliptical galaxy NGC 4472. This object has an X-ray luminosity of about 4*1039 ergs/sec, making it brighter than any non-black hole object can be in an old stellar population. The X-ray luminosity varies by a factor of 7 in a few hours, ruling out the possibility that the object is several neutron stars superposed.