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Galaxy assembly

Published online by Cambridge University Press:  17 August 2009

Eric F. Bell
Affiliation:
Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg, Germany; bell@mpia.de
Mario Livio
Affiliation:
Space Telescope Science Institute, Baltimore
Stefano Casertano
Affiliation:
Space Telescope Science Institute, Baltimore
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Summary

In a ΛCDM Universe, galaxies grow in mass both through star formation and through the addition of already-formed stars in galaxy mergers. Because of this partial decoupling of these two modes of galaxy growth, I discuss each separately in this biased and incomplete review of galaxy assembly—first giving an overview of the cosmic-averaged star formation history, and then moving on to discuss the importance of major mergers in shaping the properties of present-day massive galaxies. The cosmic-averaged star-formation rate, when integrated, is in reasonable agreement with the build-up of stellar mass density. Roughly 2/3 of all stellar mass is formed during an epoch of rapid star formation prior to z ∼ 1, with the remaining 1/3 formed in the subsequent 9 Gyr during a period of rapidly-declining star-formation rate. The epoch of important star formation in massive galaxies is essentially over. In contrast, a significant fraction of massive galaxies undergo a major merger at z ≲ 1, as evidenced by close-pair statistics, morphologically-disturbed galaxy counts, and the build-up of stellar mass in morphologically early-type galaxies. Each of these methods is highly uncertain; yet, taken together, it is not implausible that the massive galaxy population is strongly affected by late galaxy mergers, in excellent qualitative agreement with our understanding of galaxy evolution in a ΛCDM Universe.

Introduction

The last decade has witnessed amazing progress in our empirical and theoretical understanding of galaxy formation and evolution.

Type
Chapter
Information
Planets to Cosmology
Essential Science in the Final Years of the Hubble Space Telescope: Proceedings of the Space Telescope Science Institute Symposium, Held in Baltimore, Maryland May 3–6, 2004
, pp. 137 - 156
Publisher: Cambridge University Press
Print publication year: 2006

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  • Galaxy assembly
    • By Eric F. Bell, Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg, Germany; bell@mpia.de
  • Edited by Mario Livio, Space Telescope Science Institute, Baltimore, Stefano Casertano, Space Telescope Science Institute, Baltimore
  • Book: Planets to Cosmology
  • Online publication: 17 August 2009
  • Chapter DOI: https://doi.org/10.1017/CBO9780511536328.013
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To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Dropbox.

  • Galaxy assembly
    • By Eric F. Bell, Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg, Germany; bell@mpia.de
  • Edited by Mario Livio, Space Telescope Science Institute, Baltimore, Stefano Casertano, Space Telescope Science Institute, Baltimore
  • Book: Planets to Cosmology
  • Online publication: 17 August 2009
  • Chapter DOI: https://doi.org/10.1017/CBO9780511536328.013
Available formats
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Save book to Google Drive

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.

  • Galaxy assembly
    • By Eric F. Bell, Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg, Germany; bell@mpia.de
  • Edited by Mario Livio, Space Telescope Science Institute, Baltimore, Stefano Casertano, Space Telescope Science Institute, Baltimore
  • Book: Planets to Cosmology
  • Online publication: 17 August 2009
  • Chapter DOI: https://doi.org/10.1017/CBO9780511536328.013
Available formats
×