AN UPPER LIMIT TO THE DRY MERGER RATE AT (z) {approx} 0.55
- Cerro Tololo Inter-American Observatory, Casilla 603, La Serena (Chile)
- School of Physics and Astronomy, University of St. Andrews, North Haugh, St Andrews, Fife KY16 9SS (United Kingdom)
- Anglo-Australian Observatory, P.O. Box 296, Epping, NSW 1710 (Australia)
- Department of Physics, University of Queensland, Brisbane, Queensland 4072 (Australia)
- Astronomy Centre, University of Sussex, Falmer, Brighton, BN1 9QJ (United Kingdom)
- Physics Department, Durham University, South Road, Durham, DH1 3LE (United Kingdom)
- Department of Astronomy and Astrophysics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States)
We measure the fraction of luminous red galaxies (LRGs) in dynamically close pairs (with projected separation less than 20 h {sup -1} kpc and velocity difference less than 500 km s{sup -1}) to estimate the dry merger rate for galaxies with -23 < M(r) {sub k+e,z=0.2} + 5log h < -21.5 and 0.45 < z < 0.65 in the 2dF-SDSS LRG and QSO (2SLAQ) redshift survey. For galaxies with a luminosity ratio of 1:4 or greater we determine a 5{sigma} upper limit to the merger fraction of 1.1% and a merger rate of <0.8 x 10{sup -5} Mpc{sup -3} Gyr{sup -1} (assuming that all pairs merge on the shortest possible timescale set by dynamical friction). This is significantly smaller than predicted by theoretical models and suggests that major dry mergers do not contribute to the formation of the red sequence at z < 0.7.
- OSTI ID:
- 21301344
- Journal Information:
- Astronomical Journal (New York, N.Y. Online), Journal Name: Astronomical Journal (New York, N.Y. Online) Journal Issue: 2 Vol. 139; ISSN 1538-3881
- Country of Publication:
- United States
- Language:
- English
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