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| Paper: |
Multi-wavelength Observations of the Compact Binaries in the Globular Cluster M 22 |
| Volume: |
330, The Astrophysics of Cataclysmic Variables and Related Objects |
| Page: |
467 |
| Authors: |
Webb, N.A.; Gendre, B.; Barret, D. |
| Abstract: |
It is believed that that the overabundance of close binaries in globular clusters (GCs) is due to the high stellar densities and therefore large number of stellar interactions e.g. Rasio, Pfahl & Rappaport (2000). These binaries, in turn, are thought to be responsible for delaying the inevitable core collapse of these dense clusters (e.g. Hut et al. 1992). However, close binaries are hard to locate optically due to the high stellar density. Observing these clusters in X-rays, where in such a domain the compact binaries are bright, diminishes the over-crowding problem. We present recent observations with the X-ray observatory XMM-Newton of the globular cluster M 22, in which we have detected 50 low-luminosity X-ray sources. Using differential optical photometry, we have identified probable counterparts to those sources belonging to the cluster. Using X-ray spectroscopic and timing studies, supported by the optical colours, we propose that the most central X-ray sources in the cluster are predominantly cataclysmic variables but we also show evidence for the presence of millisecond pulsars, active binaries and a blue straggler. |
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