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Forming Early-Type Galaxies in Groups Prior to Cluster Assembly
Astrophysical Journal Letters
  • Stefan Kautsch, University of Florida
  • Anthony H. Gonzalez, University of Florida
  • Christian A. Soto, University of Florida
  • Kim-Vy H. Tran, University of Zürich
  • Dennis Zaritsky, University of Arizona
  • John Moustakas, New York University
Publication Date
  • Galaxies: clusters: general,
  • Galaxies: elliptical and lenticular,
  • cD,
  • Galaxies: evolution,
  • Galaxies: interactions,
  • Galaxies: spiral,
  • Galaxies: structure
We study a unique protocluster of galaxies, the supergroup SG1120–1202. We quantify the degree to which morphological transformation of cluster galaxies occurs prior to cluster assembly in order to explain the observed early-type fractions in galaxy clusters at z = 0. SG1120–1202 at z ~ 0.37 is composed of four gravitationally bound groups that are expected to coalesce into a single cluster by z = 0. Using HST ACS observations, we compare the morphological fractions of the supergroup galaxies to those found in a range of environments. We find that the morphological fractions of early-type galaxies (~60%) and the ratio of S0 to elliptical galaxies (0.5) in SG1120–1202 are very similar to clusters at comparable redshift, consistent with preprocessing in the group environment playing the dominant role in establishing the observed early-type fraction in galaxy clusters.

©2008 The American Astronomical Society.

Citation Information
Stefan Kautsch, Anthony H. Gonzalez, Christian A. Soto, Kim-Vy H. Tran, et al.. "Forming Early-Type Galaxies in Groups Prior to Cluster Assembly" Astrophysical Journal Letters Vol. 688 Iss. 1 (2008) p. L5 - L8 ISSN: 2041-8205
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