THE ENVIRONMENTAL DEPENDENCE OF THE EVOLVING S0 FRACTION
- Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)
- Division of Physics, Mathematics and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States)
- Department of Physics and Astronomy, The University of Kansas, Malott Room 1082, 1251 Wescoe Hall Drive, Lawrence, KS 66045 (United States)
We re-investigate the dramatic rise in the S0 fraction, f{sub S0}, within clusters since z {approx} 0.5. In particular, we focus on the role of the global galaxy environment on f{sub S0} by compiling, either from our own observations or the literature, robust line-of-sight velocity dispersions, sigma's, for a sample of galaxy groups and clusters at 0.1 < z < 0.8 that have uniformly determined, published morphological fractions. We find that the trend of f{sub S0} with redshift is twice as strong for sigma < 750 km s{sup -1} groups/poor clusters than for higher-sigma, rich clusters. From this result, we infer that over this redshift range galaxy-galaxy interactions, which are more effective in lower-sigma environments, are more responsible for transforming spiral galaxies into S0's than galaxy-environment processes, which are more effective in higher-sigma environments. The rapid, recent growth of the S0 population in groups and poor clusters implies that large numbers of progenitors exist in low-sigma systems at modest redshifts ({approx}0.5), where morphologies and internal kinematics are within the measurement range of current technology.
- OSTI ID:
- 21394371
- Journal Information:
- Astrophysical Journal, Vol. 711, Issue 1; Other Information: DOI: 10.1088/0004-637X/711/1/192; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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