Cosmological and Environmental Influences on Hot Gas Observed in Elliptical Galaxies

Abstract

The variation of temperature and density in the hot, X-ray emitting gas around massive, group dominant elliptical galaxies can be understood as a combination of gas ejected from evolving galactic stars and gas that accumulates in the outer halo by secondary cosmic infall. Beginning with an overdensity perturbation in a simple flat cosmology, we can duplicate observed properties of the hot gas. At some early time we form the stellar galaxy and release supernova energy, conserving dark and baryonic matter. Using a potential appropriate to the large elliptical NGC 4472, we follow the evolution of intergalactic and interstellar gas to the present time when the computed gas density and temperature agree with X-ray observations of NGC 4472. If the hot gas and dark matter halos are subject to differential tidal truncations or mass exchanges between group members, then the correlation between $L_x/L_B$ and the relative sizes of galactic X-ray images can be generated. The physical properties of hot interstellar gas observed in bright ellipticals today are sensitive to the cosmic baryon fraction, the time of maximum star formation and the amount of ``feedback'' energy delivered to the gas by Type II supernovae at the epoch of galaxy formation.

5 pages in AASTEX LaTeX including 3 figures; accepted by Astrophysical Journal Letters

References in corpus (5)

• Iron as a tracer in galaxy clusters and groups
• X-Ray Observations and the Structure of Elliptical Galaxies
• Recent X-ray Observations and the Evolution of Hot Gas in Elliptical Galaxies: Evidence for Circumgalactic Gas
• Relative Sizes of X-ray and Optical Images of Elliptical Galaxies; Correlation with X-ray Luminosity
• X-ray emission from the galaxies in Abell 2634

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• The competition between confinement and ram pressure and its implications for galaxies in groups and clusters
• The Effect of Environment on the X-Ray Emission from Early-Type Galaxies
• A Comparison of Metal Enrichment Histories in Rich Clusters and Individual Luminous Elliptical Galaxies
• Large scatter in X-ray emission among elliptical galaxies: correlations with mass of host halo
• Where Do Cooling Flows Cool?
• The X-ray Faint Early-Type Galaxy NGC4697
• Removal and mixing of the coronal gas from satellites in galaxy groups: cooling the intragoup gas
• Influence of Cooled Interstellar Gas on the Fundamental Plane for Elliptical Galaxies