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Minor-merger-driven growth of early-type galaxies over the last 8 billion years

Published online by Cambridge University Press:  17 August 2012

S. Kaviraj ,
R. M. Crockett ,
J. Silk ,
R. S Ellis ,
S. K. Yi ,
R. W. O'Connell ,
R. Windhorst  and
B. C. Whitmore
S. Kaviraj
Affiliation:
Blackett Laboratory, Imperial College London, London SW7 2AZ
R. M. Crockett
Affiliation:
Dept. of Physics, Denys Wilkinson Building, Keble Road, OX1 3RH
J. Silk
Affiliation:
Dept. of Physics, Denys Wilkinson Building, Keble Road, OX1 3RH
R. S Ellis
Affiliation:
Department of Astronomy, California Institute of Technology, Pasadena, CA 91125, USA
S. K. Yi
Affiliation:
Department of Astronomy, Yonsei University, Seoul 120-749, Republic of Korea
R. W. O'Connell
Affiliation:
Department of Astronomy, University of Virginia, Charlottesville, VA 22904-4325, USA
R. Windhorst
Affiliation:
School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287-1404, USA
B. C. Whitmore
Affiliation:
Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA email: s.kaviraj@imperial.ac.uk
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Abstract

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We summarise recent progress in understanding the star formation activity in early-type galaxies (ETGs), using recent studies that leverage photometry in the rest-frame ultraviolet (UV) wavelengths. While classically thought to be old, passively-evolving systems, recent UV studies have revealed widespread star formation in ETGs, with ~20% of the stellar mass in today's ETGs forming at late epochs (z < 1). A strong correlation is found between the presence of morphological disturbances and blue UV colours, suggesting that the star formation is merger-driven. However, the major merger rate at late epochs is far too low to satisfy the number of disturbed ETGs, indicating that minor mergers drive the star formation in these galaxies over the latter half of cosmic time. Together with the recent literature which suggests that minor mergers may drive the size evolution of massive ETGs, these results highlight the significant role of minor mergers in driving the evolution of massive galaxies in the low and intermediate-redshift Universe.

Keywords

galaxies: elliptical and lenticularcDgalaxies: formationgalaxies: evolutiongalaxies: interactionsgalaxies: high-redshiftultraviolet: galaxies
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 7 , Symposium S284: The Spectral Energy Distribution of Galaxies , September 2011 , pp. 460 - 464
Copyright
Copyright © International Astronomical Union 2012

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