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F. Gastaldello, D. Buote (Physics and Astronomy Dept., UCI), W. Mathews, F. Brighenti (UCO/Lick Observatory, UCSC)
We present results on gas density, temperature and abundance profiles for an XMM observation of NGC 1132, a so called "fossil group". These are systems which contain X-ray emitting gas with the luminosity and extent expected for groups, but in which the optical light is completely dominated by a single luminous, giant elliptical galaxy: they therefore can represent the end result of galaxy merging within a normal group.
The study of the hot gas metallicity is extremely important in this unique system, because an isolated fully merged fossil group preserves in its radial distribution information about the time sequence of star formation and supernovae events which is not disturbed by significant disruptive mergers, as when galaxy groups merge into rich clusters.
Another striking feature common to these objects seems to be an abnormally high total mass to light ratio M/L = 500-1000 solar, perhaps the consequence of an unusually low star formation efficiency. The derived mass profile will shed light on this issue.
The author(s) of this abstract have provided an email address for comments about the abstract: gasta@uci.edu
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Bulletin of the American Astronomical Society, 36 #3
© 2004. The American Astronomical Soceity.