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arXiv · 1011.1005

Cataclysmic Variables and Other Compact Binaries in the Globular Cluster NGC 362: Candidates from Chandra and HST

Bruce Margon·B. Beck-Winchatz·L. Homer·D. Pooley·C. G. Bassa·S. F. Anderson·W. H. G. Lewin·F. Verbunt·A. K. H. Kong·R. M. Plotkin
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Abstract

Highly sensitive and precise X-ray imaging from Chandra, combined with the superb spatial resolution of HST optical images, dramatically enhances our empirical understanding of compact binaries such as cataclysmic variables and low mass X-ray binaries, their progeny, and other stellar X-ray source populations deep into the cores of globular clusters. Our Chandra X-ray images of the globular cluster NGC 362 reveal 100 X-ray sources, the bulk of which are likely cluster members. Using HST color-magnitude and color-color diagrams, we quantitatively consider the optical content of the NGC 362 Chandra X-ray error circles, especially to assess and identify the compact binary population in this condensed-core globular cluster. Despite residual significant crowding in both X-rays and optical, we identify an excess population of Hα-emitting objects that is statistically associated with the Chandra X-ray sources. The X-ray and optical characteristics suggest that these are mainly cataclysmic variables, but we also identify a candidate quiescent low mass X-ray binary. A potentially interesting and largely unanticipated use of observations such as these may be to help constrain the macroscopic dynamic state of globular clusters.

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Bruce Margon, B. Beck-Winchatz, L. Homer, D. Pooley, C. G. Bassa, S. F. Anderson, W. H. G. Lewin, F. Verbunt, A. K. H. Kong, R. M. Plotkin. 2010-11-03. Cataclysmic Variables and Other Compact Binaries in the Globular Cluster NGC 362: Candidates from Chandra and HST. https://doi.org/10.1063/1.3536360

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