Role of galaxy mergers in cosmic star formation history

Yong Shi, George Rieke, Jennifer Lotz, Pablo G. Perez-Gonzalez

Research output: Contribution to journalReview article

29 Scopus citations

Abstract

We present a morphology study of intermediate-redshift (0.2 < z<1.2) luminous infrared galaxies (LIRGs) and general field galaxies in the GOODS fields using a revised asymmetry measurement method optimized for deep fields. By taking careful account of the importance of the underlying sky-background structures, our new method does not suffer from systematic bias and offers small uncertainties. By redshifting local LIRGs and low-redshift GOODS galaxies to different higher redshifts, we have found that the redshift dependence of the galaxy asymmetry due to surface-brightness dimming is a function of the asymmetry itself, with larger corrections for more asymmetric objects. By applying redshift-, infrared (IR)-luminosity- and optical-brightness-dependent asymmetry corrections, we have found that intermediate-redshift LIRGs generally show highly asymmetric morphologies, with implied merger fractions 50% up to z = 1.2, although they are slightly more symmetric than local LIRGs. For general field galaxies, we find an almost constant relatively high merger fraction (20%-30%). The B-band luminosity functions (LFs) of galaxy mergers are derived at different redshifts up to z = 1.2 and confirm the weak evolution of the merger fraction after breaking the luminosity-density degeneracy. The IR LFs of galaxy mergers are also derived, indicating a larger merger fraction at higher IR luminosity. The integral of the merger IR LFs indicates a dramatic evolution of the merger-induced IR energy density [(1 + z)(5-6)], and that galaxy mergers start to dominate the cosmic IR energy density at z ≳ 1.

Original languageEnglish (US)
Pages (from-to)1764-1783
Number of pages20
JournalAstrophysical Journal
Volume697
Issue number2
DOIs
StatePublished - Jan 1 2009

Keywords

  • Galaxies: interactions
  • Infrared: galaxies

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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