EDP Sciences
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Volume 424, Number 1, September II 2004
Page(s) 133 - 143
Section Galactic structure, stellar clusters and populations
DOI http://dx.doi.org/10.1051/0004-6361:20040399

A&A 424, 133-143 (2004)
DOI: 10.1051/0004-6361:20040399

X-ray sources and their optical counterparts in the globular cluster M 22

N. A. Webb1, D. Serre1, B. Gendre1, 2, D. Barret1, J.-P. Lasota3 and L. Rizzi4

1  Centre d'Étude Spatiale des Rayonnements, 9 avenue du Colonel Roche, 31028 Toulouse Cedex 04, France
    e-mail: Natalie.Webb@cesr.fr
2  Istituto di Astrofisica Spaziale e Fisica Cosmica, CNR, via Fosso del Cavaliere, Roma, Italy
3  Institut d'Astrophysique de Paris, 98bis boulevard Arago, 75014 Paris, France
4  INAF, Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122 Padua, Italy

(Received 5 March 2004 / Accepted 26 May 2004)

Using XMM-Newton EPIC imaging data, we have detected 50 low-luminosity X-ray sources in the field of view of M 22, where $5\pm3$ of these sources are likely to be related to the cluster. 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 cataclysmic variables, millisecond pulsars, active binaries and a blue straggler. We also identify a cluster of galaxies behind this globular cluster.

Key words: Galaxy: globular clusters: individual: M 22 -- X-rays: general -- stars: binaries: general -- galaxies: clusters: general

SIMBAD Objects

© ESO 2004