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J. S. Mulchaey (Carnegie Observatories), A. I. Zabludoff (Lick Observatory)
Numerical simulations predict that some poor groups of galaxies have merged by the present epoch into giant ellipticals. To identify the possible remnants of such mergers, we have compiled a sample of nearby, isolated elliptical galaxies.ASCA observations of the first galaxy studied, NGC 1132,reveal an X-ray halo that extends out to at least 250 kpc h100-1. The temperature, metallicity and luminosity of NGC 1132's halo are comparable to those of poor groups. Optical imaging uncovers a dwarf galaxy population clustered about NGC 1132 that is consistent in number density and in projected radial distribution with that of an X-ray group. The similarity of NGC 1132 to poor groups in both the X-ray band and at the faint end of the galaxy luminosity function, combined with the deficit of luminous galaxies in the NGC 1132 field, are compatible with the merged group picture. Another possibility is that the NGC 1132 system is a `failed' group.
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The author(s) of this abstract have provided an email address for comments about the abstract: mulchaey@pegasus.ociw.edu