The cold and hot gas content of fine-structure E and S0 galaxies.
SANSOM A.E., HIBBARD J.E. and SCHWEIZER F.
Abstract (from CDS):
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 Σ. H I mapping observations from the literature are used to track the cold gas content, and archival ROSAT Position Sensitive Proportional Counter 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 Σ. 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 timescale of several gigayears. This is consistent with the expected mass loss from stars.
Galaxies: Evolution - Galaxies: ISM - Galaxies: Peculiar