Annu. Rev. Astron. Astrophys. 2005. 43: 677-725
Copyright © 2005 by . All rights reserved

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MOLECULAR GAS AT HIGH REDSHIFT

P.M. Solomon, P.A. Vanden Bout


Abstract. The Early Universe Molecular Emission Line Galaxies (EMGs) are a population of galaxies with only 36 examples that hold great promise for the study of galaxy formation and evolution at high redshift. The classification, luminosity of molecular line emission, molecular mass, far-infrared (FIR) luminosity, star formation efficiency, morphology, and dynamical mass of the currently known sample are presented and discussed. The star formation rates derived from the FIR luminosity range from about 300 to 5000 Modot year-1 and the molecular mass from 4 × 109 to 1 × 1011 Modot. At the lower end, these star formation rates, gas masses, and diameters are similar to those of local ultraluminous infrared galaxies, and represent starbursts in centrally concentrated disks, sometimes, but not always, associated with active galactic nuclei. The evidence for large (> 5 kpc) molecular disks is limited. Morphology and several high angular resolution images suggest that some EMGs are mergers with a massive molecular interstellar medium in both components. A critical question is whether the EMGs, in particular those at the higher end of the gas mass and luminosity distribution, represent the formation of massive, giant elliptical galaxies in the early Universe. The sample size is expected to grow explosively in the era of the Atacama Large Millimeter Array (ALMA).


Table of Contents

INTRODUCTION

DEFINING THE EMGs
Luminosities: Basic Relations
From CO Luminosity to Molecular Mass
Classification of the EMGs
Examples of EMGs

DISCUSSION
Molecular Gas Mass and Star Formation Efficiency
Star Formation and Gas Depletion Lifetime
HCN, [CI], & [CII] Emission
Masses, Sizes, & Evolutionary Destiny

OBSERVATIONAL PROSPECTS

REFERENCES

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