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arXiv · 2508.10105

The X-ray Source Population of the Metal-Rich Globular Cluster NGC 6528

Bernard Leal·Kwangmin Oh·Jay Strader·Steve E. Zepf·Kristen Dage·S. Kim·C. Y. Hui
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Abstract

We present the first study of the X-ray sources in one of the most metal-rich globular clusters in the Galaxy, NGC 6528. Using relatively deep (66 ksec) archival imaging from the Chandra X-ray Observatory, we identify 18 sources within the half-light radius of the cluster, all in the range $L_X \sim 10^{31}$-$10^{32}$erg s$^{-1}$ (0.5-7 keV). By combining these data with photometry from the Hubble Space Telescope and other sources, we classify the X-ray sources as a likely mix of cataclysmic variables and active binaries, though one or more of the brighter objects could be a quiescent low-mass X-ray binary. For this cluster, it appears that the X-ray binary-enhancing effects of high metallicity are outweighed by the cluster's advanced dynamical evolution, leading to a relatively modest X-ray source population.

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Bernard Leal, Kwangmin Oh, Jay Strader, Steve E. Zepf, Kristen Dage, S. Kim, C. Y. Hui. 2025-08-13. The X-ray Source Population of the Metal-Rich Globular Cluster NGC 6528. https://arxiv.org/abs/2508.10105

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