2005/03/23 by Marcin Sawicki, Matthew Stevenson, M. A. Stevenson +5 · 2 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Galaxies: Formation, Evolution, Phenomena #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/430466
published as Astrophys.J. 627 (2005) 621-631 · uses emulateapj
arxiv created 2005/03/23 · openalex publication_date 2005/07/06 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
We use a serendipitously discovered overdensity of extremely red objects (EROs) to study the morphologies and cumulative surface number density of EROs in a dense environment. Our extremely deep imaging allows us to select very faint EROs, reaching K S = 21, or ~2 mag fainter than the L * of passively evolving ellipticals at z = 1.5. We find that the shape of the ERO cumulative surface number density in our overdense field mimics that of the field ERO population over all magnitudes down to K S = 21 but with a factor of 3-4 higher normalization. The excellent seeing in our images (0 4 in K S and 0 6 in R ) allows for morphological classification of the brighter ( K S < 19) EROs, and we find a mix of morphologies including interacting systems and disks; the fraction of pure bulges (at most 38%), galaxies with disks (at least 46%), and interacting systems (at least 21%) is consistent with morphological fractions in field ERO studies. The similarity in the shape of the cumulative surface density and morphological mix between our overdense field and the field ERO population suggests that ERO galaxies in overdense regions at z ~ 1-2 may not have had an appreciably different history from those in the field.