Abstract
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 SO 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.
Original language | English (US) |
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Pages (from-to) | L5-L8 |
Journal | Astrophysical Journal |
Volume | 687 |
Issue number | 1 PART 2 |
DOIs | |
State | Published - 2008 |
Keywords
- Galaxies: Clusters: General
- Galaxies: Elliptical and lenticular cD
- Galaxies: Evolution
- Galaxies: Interactions
- Galaxies: Spiral
- Galaxies: Structure
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science