We discuss CXOU~1229410+075744, a new black hole candidate in a globular cluster in the elliptical galaxy NGC~4472. By comparing two Chandra observations of the galaxy, we find a source that varies by at least a factor of 4, and has a peak luminosity of at least 2×1039 ergs/sec. As such, the source varies by significantly more than the Eddington luminosity for a single neutron star, and is a strong candidate for being a globular cluster black hole. The source's X-ray spectrum also evolves in a manner consistent with what would be expected from a single accreting stellar mass black hole. We consider the properties of the host cluster of this source and the six other strong black hole X-ray binary candidates, and find that there is suggestive evidence that black hole X-ray binary formation is favored in bright and metal rich clusters, just as is the case for bright X-ray sources in general.
@article{arxiv.1008.2896,
title = {A new globular cluster black hole in NGC 4472},
author = {Thomas J. Maccarone and Arunav Kundu and Stephen E. Zepf and Katherine L. Rhode},
journal= {arXiv preprint arXiv:1008.2896},
year = {2015}
}
Comments
6 pages, one 2-panel figure, 2 tables; accepted to MNRAS