Chandra X-Ray Sources in the Collapsed-Core Globular Cluster M30 (NGC 7099)
We report the detection of six discrete, low-luminosity (L sub(x) < 10 super(33) ergs s super(-1)) X-ray sources, located within 12" of the center of the collapsed-core globular cluster M30 (NGC 7099), and a total of 13 sources within the half-mass radius, from a 50 ks Chandra ACIS-S exposur...
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Veröffentlicht in: | The Astrophysical journal 2007-03, Vol.657 (1), p.286-301 |
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Sprache: | eng |
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Zusammenfassung: | We report the detection of six discrete, low-luminosity (L sub(x) < 10 super(33) ergs s super(-1)) X-ray sources, located within 12" of the center of the collapsed-core globular cluster M30 (NGC 7099), and a total of 13 sources within the half-mass radius, from a 50 ks Chandra ACIS-S exposure. Three sources lie within the very small upper limit of 1.9" on the core radius. The brightest of the three core sources has a luminosity of L sub(X)(0.5--6 keV) - 6 x 10 super(32) ergs s super(-1) and a blackbody-like soft X-ray spectrum, which are both consistent with it being a quiescent low-mass X-ray binary (qLMXB). We have identified optical counterparts to four of the six central sources and a number of the outlying sources, using deep Hubble Space Telescope and ground-based imaging. While the two proposed counterparts that lie within the core may represent chance superpositions, the two identified central sources that lie outside of the core have X-ray and optical properties consistent with being cataclysmic variables (CVs). Two additional sources outside of the core have possible active binary counterparts. We discuss the X-ray source population of M30 in light of its collapsed-core status. |
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ISSN: | 0004-637X 1538-4357 |
DOI: | 10.1086/507572 |