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Title: THE OPTICAL GREEN VALLEY VERSUS MID-INFRARED CANYON IN COMPACT GROUPS

Compact groups of galaxies provide conditions similar to those experienced by galaxies in the earlier universe. Recent work on compact groups has led to the discovery of a dearth of mid-infrared transition galaxies (MIRTGs) in Infrared Array Camera (3.6-8.0 μm) color space as well as at intermediate specific star formation rates. However, we find that in compact groups these MIRTGs have already transitioned to the optical ([g–r]) red sequence. We investigate the optical color-magnitude diagram (CMD) of 99 compact groups containing 348 galaxies and compare the optical CMD with mid-infrared (mid-IR) color space for compact group galaxies. Utilizing redshifts available from Sloan Digital Sky Survey, we identified new galaxy members for four groups. By combining optical and mid-IR data, we obtain information on both the dust and the stellar populations in compact group galaxies. We also compare with more isolated galaxies and galaxies in the Coma Cluster, which reveals that, similar to clusters, compact groups are dominated by optically red galaxies. While we find that compact group transition galaxies lie on the optical red sequence, LVL+SINGS mid-IR transition galaxies span the range of optical colors. The dearth of mid-IR transition galaxies in compact groups may be due to a lackmore » of moderately star-forming low mass galaxies; the relative lack of these galaxies could be due to their relatively small gravitational potential wells. This makes them more susceptible to this dynamic environment, thus causing them to more easily lose gas or be accreted by larger members.« less
Authors:
; ; ;  [1] ;  [2] ;  [3] ;  [4] ; ;  [5] ;  [6]
  1. Astronomy Department, University of Virginia, Charlottesville, VA 22904 (United States)
  2. Department of Physics and Astronomy, University of Western Ontario, London, ON N6A 3K7 (Canada)
  3. Australian Astronomical Observatory, North Ryde, NSW 1670 (Australia)
  4. Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States)
  5. Laboratory for X-Ray Astrophysics, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
  6. Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States)
Publication Date:
OSTI Identifier:
22270869
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 775; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTRONOMY; ASTROPHYSICS; CAMERAS; COLOR; COMPARATIVE EVALUATIONS; COSMIC DUST; DIAGRAMS; GALAXIES; INTERMEDIATE INFRARED RADIATION; MASS; PHOTOMETRY; POTENTIALS; RED SHIFT; SPACE; STAR EVOLUTION; STARS; UNIVERSE