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Publication Details
AFRICAN RESEARCH NEXUS
SHINING A SPOTLIGHT ON AFRICAN RESEARCH
earth and planetary sciences
Dry mergers in GEMS: The dynamical evolution of massive early-type galaxies
Astrophysical Journal, Volume 640, No. 1 I, Year 2006
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Description
We have used the 28′ × 28′ Hubble Space Telescope image mosaic from the GEMS (Galaxy Evolution from Morphology and SEDs) survey in conjunction with the COMBO-17 photometric redshift survey to constrain the incidence of major mergers between spheroid-dominated galaxies with little cold gas (dry mergers) since z = 0.7. A set of N-body merger simulations was used to explore the morphological signatures of such interactions: they are recognizable either as <5 kpc separation close pairs or because of broad, low surface brightness tidal features and asymmetries. Data with the depth and resolution of GEMS are sensitive to dry mergers between galaxies with MV ≲ - 20.5 for z ≲ 0.7; dry mergers at higher redshifts are not easily recovered in single-orbit HST imaging. Six dry mergers (12 galaxies) with luminosity ratios between 1 :1 and 4:1 were found from a sample of 379 red early-type galaxies with MV < -20.5 and 0.1 < z < 0.7. The simulations suggest that the morphological signatures of dry merging are visible for ∼150 Myr, and we use this timescale to convert the observed merger incidence into a rate. On this basis we find that present-day spheroidal galaxies with MV < -20.5 on average have undergone between 0.5 and 2 major dry mergers since z ∼ 0.7. We have compared this result with the predictions of a cold dark matter-based semianalytic galaxy formation model. The model reproduces the observed declining major merger fraction of bright galaxies and the space density of luminous early-type galaxies reasonably well. The predicted dry merger fraction is consistent with our observational result. Hence, hierarchical models predict and observations now show that major dry mergers are an important driver of the evolution of massive early-type galaxies in recent epochs. © 2006. The American Astronomical Society. All rights reserved.
Authors & Co-Authors
Bell, Eric F.
Germany, Heidelberg
Max Planck Institute for Astronomy
Naab, Thorsten
Germany, Munich
Ludwig-maximilians-universität München
McIntosh, Daniel H.
United States, Amherst
University of Massachusetts Amherst
Somerville, Rachel S.
United States, Baltimore
Space Telescope Science Institute
Caldwell, John A.R.
United States, Austin
University of Texas System
Rix, Hans Walter R.
Germany, Heidelberg
Max Planck Institute for Astronomy
Häussler, Boris
Germany, Heidelberg
Max Planck Institute for Astronomy
Heymans, Catherine E.
Germany, Heidelberg
Max Planck Institute for Astronomy
Canada, Vancouver
The University of British Columbia
Jahnke, Knud
Germany, Potsdam
Leibniz Institute for Astrophysics Potsdam
Jogee, Shardha
United States, Austin
The University of Texas at Austin
Koposov, Sergey E.
Germany, Heidelberg
Max Planck Institute for Astronomy
Meisenheimer, Klauss
Germany, Heidelberg
Max Planck Institute for Astronomy
Peng, Chien Y.
United States, Baltimore
Space Telescope Science Institute
Sánchez, Sebastián F.
Spain, Almeria
Centro Astronómico Hispano-alemán
Wisotzki, Lutz
Canada, Vancouver
The University of British Columbia
Statistics
Citations: 242
Authors: 15
Affiliations: 12
Identifiers
Doi:
10.1086/499931
ISSN:
0004637X
Study Design
Cross Sectional Study
Cohort Study
Study Approach
Quantitative