LUMINOUS INFRARED GALAXIES WITH THE SUBMILLIMETER ARRAY. II. COMPARING THE CO (3-2) SIZES AND LUMINOSITIES OF LOCAL AND HIGH-REDSHIFT LUMINOUS INFRARED GALAXIES Academic Article uri icon

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abstract

  • We present a detailed comparison of the CO(3-2) emitting molecular gas between a local sample of luminous infrared galaxies (U/LIRGs) and a high redshift sample that comprises submm selected galaxies (SMGs), quasars, and Lyman Break Galaxies (LBGs). The U/LIRG sample consists of our recent CO(3-2) survey using the Submillimeter Array while the CO(3-2) data for the high redshift population are obtained from the literature. We find that the L(CO(3-2)) and L(FIR) relation is correlated over five orders of magnitude, which suggests that the molecular gas traced in CO(3-2) emission is a robust tracer of dusty star formation activity. The near unity slope of 0.93 +/- 0.03 obtained from a fit to this relation suggests that the star formation efficiency is constant to within a factor of two across different types of galaxies residing in vastly different epochs. The CO(3-2) size measurements suggest that the molecular gas disks in local U/LIRGs (0.3 - 3.1 kpc) are much more compact than the SMGs (3 - 16 kpc), and that the size scales of SMGs are comparable to the nuclear separation (5 - 40 kpc) of the widely separated nuclei of U/LIRGs in our sample. We argue from these results that the SMGs studied here are predominantly intermediate stage mergers, and that the wider line-widths arise from the violent merger of two massive gas-rich galaxies taking place deep in a massive halo potential.

authors

  • Iono, Daisuke
  • Wilson, Christine D
  • Yun, Min S
  • Baker, Andrew J
  • Petitpas, Glen R
  • Peck, Alison B
  • Krips, Melanie
  • Cox, TJ
  • Matsushita, Satoki
  • Mihos, J Christopher
  • Pihlstrom, Ylva

publication date

  • April 20, 2009