Is the Fast Evolution Scenario for Virialized Compact Groups Really Compelling? The Role of a Dark Massive Group Halo

Abstract

We report on results of N-body simulations aimed at testing the hypothesis that galaxies in X-ray emitting (i.e., virialized) Compact Groups are not tidally stripped when they are embedded in a common, massive, quiescent dark matter halo. To disentangle the effects of interactions from spurious effects due to an incorrect choice of the initial galaxy model configurations, these have been chosen to be tidally-limited King spheres, representing systems in quasi-equilibrium within the tidal field of the halo. The potential of the halo has been assumed to be frozen and the braking due to dynamical friction neglected. Our results confirm the hypothesis of low rates of tidal stripping and suggest a scenario for virialized Compact Group evolution in their quiescent phases with only very moderate tidally induced galaxy evolution can be generally expected. This implies the group stability, provided that the dynamical friction timescales in these systems are not much shorter than the Hubble time. We discuss briefly this possibility, in particular taking account of the similarity between the velocity dispersions of a typical virialized Compact Groups and the internal velocity dispersion of typical member galaxies. A number of puzzling observational data on Compact Groups can be easily explained in this framework. Other observations would be better understood as the result of enhanced merging activity in the proto-group environment, leading to virialized Compact Group formation through mergers of lower mass halos, as predicted by hierarchical scenarios of structure formation.

18 pages, 1 postscript file, 2 tables, to be published in ApJLett

References in corpus (5)

• X-ray Properties of Groups of Galaxies
• The Relation Between Activity and Environment in Compact Groups of Galaxies
• A Dynamical Study of Galaxies in the Hickson Compact Groups
• Compact Groups of Galaxies in the Las Campanas Redshift Survey
• On the Stability of Quasi-Equilibrium Self-Gravitating Configurations in a Tidal Field

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• Properties of Hickson Compact Groups and of the Loose Groups within which they are Embedded
• The DPOSS II compact group survey: first spectroscopically confirmed candidates
• Galaxy evolution in compact groups II. Witnessing the influence of major structures in their evolution
• Detection of a hot intergalactic medium in the spiral-only compact group SCG0018-4854
• Stellar Population Properties of ETGs in Compact Groups of Galaxies