THE MERGER-DRIVEN EVOLUTION OF MASSIVE GALAXIES
- Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, D-69117 Heidelberg (Germany)
- Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48105 (United States)
- Space Telescope Science Institute, 3700 San Martin Dr., Baltimore, MD 21218 (United States)
- Department of Physics, University of Missouri-Kansas City, Kansas City, MO 64110 (United States)
- Department of Physics, Denys Wilkinson Bldg., University of Oxford, Keble Road, Oxford, OX1 3RH (United Kingdom)
We explore the rate and impact of galaxy mergers on the massive galaxy population using the amplitude of the two-point correlation function on small scales for M {sub *} > 5 x 10{sup 10} M {sub sun} galaxies from the COSMOS and COMBO-17 surveys. Using a pair fraction derived from the Sloan Digital Sky Survey as a low-redshift benchmark, the large survey area at intermediate redshifts allows us to determine the evolution of the close-pair fraction with unprecedented accuracy for a mass-selected sample: we find that the fraction of galaxies more massive than 5 x 10{sup 10} M {sub sun} in pairs separated by less than 30 kpc in three-dimensional space evolves as F(z) = (0.0130 {+-} 0.0019) x (1 + z){sup 1.21{+-}0.25} between z = 0 and z = 1.2. Assuming a merger timescale of 0.5 Gyr, the inferred merger rate is such that galaxies with mass in excess of 10{sup 11} M {sub sun} have undergone, on average, 0.5 (0.7) mergers involving progenitor galaxies both more massive than 5 x 10{sup 10} M {sub sun} since z = 0.6 (1.2). We also study the number density evolution of massive red sequence galaxies using published luminosity functions and constraints on the M/L {sub B} evolution from the fundamental plane. Moreover, we demonstrate that the measured merger rate of massive galaxies is sufficient to explain this observed number density evolution in massive red sequence galaxies since z = 1.
- OSTI ID:
- 21454965
- Journal Information:
- Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 719; ISSN ASJOAB; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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