THE DIRT ON DRY MERGERS

Journal Article · Fri Apr 01 04:00:00 EDT 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/730/2/130· OSTI ID:21574820

Desai, Vandana; Soifer, B T ^[1]; Dey, Arjun ^[2]; Cohen, Emma ^[3]

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1. Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125 (United States)
2. National Optical Astronomy Observatory, Tucson, AZ 85726-6732 (United States)
3. California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States)

Using data from the Spitzer Space Telescope, we analyze the mid-infrared (3-70 {mu}m) spectral energy distributions of dry merger candidates in the Booetes field of the NOAO Deep Wide-Field Survey. These candidates were selected by previous authors to be luminous, red, early-type galaxies with morphological evidence of recent tidal interactions. We find that a significant fraction of these candidates exhibit 8 and 24 {mu}m excesses compared to expectations for old stellar populations. We estimate that a quarter of dry merger candidates have mid-infrared-derived star formation rates greater than {approx}1 M{sub sun} yr{sup -1}. This represents a 'frosting' on top of a large old stellar population, and has been seen in previous studies of elliptical galaxies. Further, the dry merger candidates include a higher fraction of star-forming galaxies relative to a control sample without tidal features. We therefore conclude that the star formation in these massive ellipticals is likely triggered by merger activity. Our data suggest that the mergers responsible for the observed tidal features were not completely dry, and may be minor mergers involving a gas-rich dwarf galaxy.

• OSTI ID: 21574820
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 730; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ENERGY SPECTRA
EVOLUTION
GALACTIC EVOLUTION
GALAXIES
INFRARED SPECTRA
SPECTRA
STAR EVOLUTION