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The Dominant Role of Mergers in the Size Evolution of Massive Galaxies since z∼1

López-Sanjuan, Carlos and Le Fèvre, Olivier and Ilbert, Olivier and Tasca, Lidia (2013) The Dominant Role of Mergers in the Size Evolution of Massive Galaxies since z∼1. In: Galaxy Mergers in an Evolving Universe. Astronomical Society of the Pacific Conference Series. No.477. Astronomical Society of the Pacific , San Francisco, CA, pp. 159-162. ISBN 978-1-58381-838-1. http://resolver.caltech.edu/CaltechAUTHORS:20150710-083347982

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Abstract

We estimate the merger rate, both major (stellar mass ratio μ = M★,_2/M★,_1 ≥ 1/4) and minor (1/10 ≤ μ < 1/4), of massive (M★ ≥ 10^(11) M☉) early-type galaxies (ETGs) in the COSMOS field by close pairs statistics. The merger rate of massive ETGs evolves as a power-law (1+z)^n, showing the minor merger little evolution with redshift, n_(mm) ∼ 0, in contrast with the increase of major mergers, n_(MM) = 1.8. Our results shows that massive ETGs have undergone 0.89 mergers (0.43 major and 0.46 minor) since z ∼ 1, leading to a mass growth of ∼ 30%. In addition, μ ≥ 1/10 mergers can explain ∼ 55% of the observed size evolution of these galaxies since z ∼ 1. Another ∼ 20% is due to the progenitor bias (younger galaxies are more extended) and we estimate that very minor mergers (μ < 1/10) could contribute with an extra ∼ 20%. The remaining ∼ 5% should come from other processes (e.g., adiabatic expansion or observational effects). These results suggest that mergers are the main contributor to the size evolution of massive ETGs, accounting for ∼ 55%–75% of that evolution in the last 8 Gyr. Nearly half of this merging evolution is related with minor (μ < 1/4) events.


Item Type:Book Section
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http://www.aspbooks.org/a/volumes/article_details/?paper_id=35813PublisherArticle
Additional Information:© 2013 Astronomical Society of the Pacific. C. L. S. acknowledge the LOC and the SOC for a suggesting meeting in an exceptional location, and the financial support from the ERC Advanced Grant n°268107 - EARLY.
Group:COSMOS
Funders:
Funding AgencyGrant Number
European Research Council (ERC)268107
Record Number:CaltechAUTHORS:20150710-083347982
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20150710-083347982
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:58835
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:14 Jul 2015 16:14
Last Modified:14 Jul 2015 16:14

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