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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 448168.0, MPI für Astronomie / Publikationen_mpia
History of galaxy interactions and their impact on star formation over the last 7 Gyr from GEMS
Authors:Jogee, Shardha; Miller, Sarah H.; Penner, Kyle; Skelton, Rosalind E.; Conselice, Christopher J.; Somerville, Rachel S.; Bell, Eric F.; Zheng, Xian Zhong; Rix, Hans-Walter; Robaina, Aday R.; Barazza, Fabio D.; Barden, Marco; Borch, Andrea; Beckwith, Steven V. W.; Caldwell, John A. R.; Peng, Chien Y.; Heymans, Catherine; McIntosh, Daniel H.; Häußler, Boris; Jahnke, Knud; Meisenheimer, Klaus; Sanchez, Sebastian F.; Wisotzki, Lutz; Wolf, Christian; Papovich, Casey
Date of Publication (YYYY-MM-DD):2009
Title of Journal:The Astrophysical Journal
Journal Abbrev.:ApJ
Start Page:1971
End Page:1992
Review Status:not specified
Audience:Experts Only
Abstract / Description:We perform a comprehensive estimate of the frequency of galaxy mergers and their impact on star formation over z~ 0.24-0.80 (lookback time T b~ 3-7 Gyr) using ~3600 (M>= 1 × 109 M sun) galaxies with GEMS Hubble Space Telescope, COMBO-17, and Spitzer data. Our results are as follows. (1) Among ~790 high-mass (M>= 2.5 × 1010 M sun) galaxies, the visually based merger fraction over z~ 0.24-0.80, ranges from 9% ± 5% to 8% ± 2%. Lower limits on the major merger and minor merger fraction over this interval range from 1.1% to 3.5%, and 3.6% to 7.5%, respectively. This is the first, albeit approximate, empirical estimate of the frequency of minor mergers over the last 7 Gyr. Assuming a visibility timescale of ~0.5 Gyr, it follows that over T b~ 3-7 Gyr, ~68% of high-mass systems have undergone a merger of mass ratio >1/10, with ~16%, 45%, and 7% of these corresponding respectively to major, minor, and ambiguous "major or minor" mergers. The average merger rate is ~ a few ×10--4 galaxies Gyr--1 Mpc--3. Among ~2840 blue-cloud galaxies of mass M>= 1.0 × 109 M sun, similar results hold. (2) We compare the empirical merger fraction and merger rate for high-mass galaxies to three Lambda cold dark matter-based models: halo occupation distribution models, semi-analytic models, and hydrodynamic SPH simulations. We find qualitative agreement between observations and models such that the (major+minor) merger fraction or rate from different models bracket the observations, and show a factor of 5 dispersion. Near-future improvements can now start to rule out certain merger scenarios. (3) Among ~3698 M>= 1.0 × 109 M sun galaxies, we find that the mean star formation rate (SFR) of visibly merging systems is only modestly enhanced compared to non-interacting galaxies over z~ 0.24-0.80. Visibly merging systems only account for a small fraction (<30%) of the cosmic SFR density over T b~ 3-7 Gyr. This complements the results of Wolf et al. over a shorter time interval of T b~ 6.2-6.8 Gyr, and suggests that the behavior of the cosmic SFR density over the last 7 Gyr is predominantly shaped by non-interacting galaxies.
Free Keywords:galaxies: evolution; galaxies: fundamental parameters; galaxies: kinematics and dynamics; galaxies: structure
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:URL:http://adsabs.harvard.edu/abs/2009ApJ...697.1971J [ID No:1]
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