Cold & Hot Gas Content of Fine Structure E and S0 Galaxies

Anne Sansom, University of Central Lancashire
J. E. Hibbard, NRAO
F. Schweizer, The Observatories of the Carnegie Institution of Washington

The Astronomical Journal, 120, 1946 (2000) (astro-ph/0007188);

We investigate trends of the cold and hot gas content of early-type galaxies with the presence of optical morphological peculiarities, as measured by the fine-structure index. HI mapping observations from the literature are used to track the cold-gas content, and archival ROSAT PSPC data are used to quantify the hot-gas content. We find that E and S0 galaxies with a high incidence of optical peculiarities are exclusively X-ray underluminous and, therefore, deficient in hot gas. In contrast, more relaxed galaxies with little or no signs of optical peculiarities span a wide range of X-ray luminosities. That is, the X-ray excess anticorrelates with fine structure. There appears to be no similar trend of cold-gas content with either fine-structure index or X-ray content. The fact that only apparently relaxed E and S0 galaxies are strong X-ray emitters is consistent with the hypothesis that after strong disturbances such as a merger hot-gas halos build up over a time scale of several gigayears. This is consistent with the expected mass loss from stars.
See also Paper I: HI Mapping of Five Fine-Structure Ellipticals, and HI in Early Types

John Hibbard
Last modified: Fri Jul 30 17:20:12 EDT 2004