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Caltech Faint Galaxy Redshift Survey. XI. The Merger Rate to Redshift 1 from Kinematic Pairs

Carlberg, R. G. and Cohen, Judith G. and Patton, D. R. and Blandford, Roger and Hogg, David W. and Yee, H. K. C. and Morris, S. L. and Lin, H. and Hall, Patrick B. and Sawicki, M. and Wirth, Gregory D. and Cowie, Lennox L. and Hu, Esther and Songaila, Antoinette (2000) Caltech Faint Galaxy Redshift Survey. XI. The Merger Rate to Redshift 1 from Kinematic Pairs. Astrophysical Journal, 532 (1). L1-L4. ISSN 0004-637X.

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The rate of mass accumulation due to galaxy merging depends on the mass, density, and velocity distribution of galaxies in the near neighborhood of a host galaxy. The fractional luminosity in kinematic pairs combines all of these effects in a single estimator that is relatively insensitive to population evolution. Here we use a k-corrected and evolution-compensated volume-limited sample having an R-band absolute magnitude of M^(k,e)_R ≤ -19.8 + 5 log h mag drawing about 300 redshifts from the Caltech Faint Galaxy Redshift Survey and 3000 from the Canadian Network for Observational Cosmology field galaxy survey to measure the rate and redshift evolution of merging. The combined sample has an approximately constant comoving number and luminosity density from redshift 0.1 to 1.1 (Ω_M = 0.2, Ω_Λ = 0.8); hence, any merger evolution will be dominated by correlation and velocity evolution, not density evolution. We identify kinematic pairs with projected separations less than either 50 or 100 h^(-1) kpc and rest-frame velocity differences of less than 1000 km s^(-1). The fractional luminosity in pairs is modeled as f_L(Δv, r_p, M^(k,e)_τ)(1 + z)^(m,L), where [f_L, m_L] are [0.14 ± 0.07, 0 ± 1.4] and [0.37 ± 0.7, 0.1 ± 0.5] for r_p ≤ 50 and 100 h^(-1) kpc, respectively (Ω_M = 0.2, Ω_Λ = 0.8). The value of mL is about 0.6 larger if Λ = 0. To convert these redshift-space statistics to a merger rate, we use the data to derive a conversion factor to a physical space pair density, a merger probability, and a mean in-spiral time. The resulting mass accretion rate per galaxy (M_1, M_2 ≥ 0.2M*) is 0.02 ± 0.01(1 + z)^(0.1±0.5)M* Gyr^(-1). Present-day high-luminosity galaxies therefore have accreted approximately 0.15M* of their mass over the approximately 7 Gyr to redshift 1. Since merging is likely only weakly dependent on the host mass, the fractional effect, δM/M 0.15M*/M, is dramatic for lower mass galaxies but is, on the average, effectively perturbative for galaxies above 1M*.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Cohen, Judith G.0000-0002-8039-4673
Blandford, Roger0000-0002-1854-5506
Hogg, David W.0000-0003-2866-9403
Sawicki, M.0000-0002-7712-7857
Cowie, Lennox L.0000-0002-6319-1575
Alternate Title:The Merger Rate to Redshift One from Kinematic Pairs: Caltech Faint Galaxy Redshift Survey XI
Additional Information:© 2000 The American Astronomical Society. Received 1999 December 7; accepted 2000 February 1; published 2000 March 3. This research was supported by NSERC and NRC of Canada. H. L. and D. W. H. acknowledge support provided by NASA through Hubble Fellowship grants HF-01110.01-98A and HF-01093.01-97A, respectively, awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA under contract NAS5-26555.
Funding AgencyGrant Number
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
National Research Council of CanadaUNSPECIFIED
NASA Hubble FellowshipHF-01110.01-98A
NASA Hubble FellowshipHF-01093.01-97A
Subject Keywords:galaxies: evolution—large-scale structure of universe
Issue or Number:1
Record Number:CaltechAUTHORS:20190524-135650384
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Official Citation:R. G. Carlberg et al 2000 ApJ 532 L1
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:95793
Deposited By: Tony Diaz
Deposited On:24 May 2019 21:16
Last Modified:09 Mar 2020 13:19

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