Chandra X-ray Sources in the Collapsed-core Globular Cluster M30 (ngc 7099)

We report the detection of six discrete, low-luminosity (LX < 1033 erg s−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 ksec 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 LX (0.5–6 keV) ≈ 6×1032 erg s−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 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. Subject headings: globular clusters: individual (M30, NGC 7099) — X-rays: binaries — novae, cataclysmic variables — stars: neutron