A New Black Hole X-ray Transient Candidate in M51
Abstract
Even with more than 13 years of high spatial resolution observations of external galaxies, black hole X-ray transients have been rarely identified in galaxies beyond the local group. Using a new set of Chandra X-ray Observatory observations of the nearby interacting galaxy M51, we report on the discovery of a new black hole X-ray transient candidate. The source reaches a maximum luminosity of just over 1e39 erg/s with a featureless multicolor disk blackbody spectrum with temperature 1.2 keV, consistent with Galactic black hole X-ray binaries in the disk-dominant state. Using archival Hubble Space Telescope observations, we determine that the source does not have a high-mass companion star, and there is no significant nearby H-alpha emission. As such, it is probably not associated with the star formation triggered by the interaction. While the X-ray luminosity makes this source a borderline ultraluminous X-ray source, the spectral properties demonstrate that the source is likely a stellar-mass black hole LMXB similar to those in the Milky Way.
- Publication:
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American Astronomical Society Meeting Abstracts #221
- Pub Date:
- January 2013
- Bibcode:
- 2013AAS...22114226K