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Title: STRONG C{sup +} EMISSION IN GALAXIES AT z ∼ 1-2: EVIDENCE FOR COLD FLOW ACCRETION POWERED STAR FORMATION IN THE EARLY UNIVERSE

We have recently detected the [C II] 157.7 μm line in eight star-forming galaxies at redshifts 1 to 2 using the redshift (z) Early Universe Spectrometer (ZEUS). Our sample targets star formation dominant sources detected in PAH emission. This represents a significant addition to [C II] observations during the epoch of peak star formation. We have augmented this survey with observations of the [O I] 63 μm line and far infrared photometry from the PACS and SPIRE Herschel instruments as well as Spitzer IRS spectra from the literature showing PAH features. Our sources exhibit above average gas heating efficiency, many with both [O I]/FIR and [C II]/FIR of ∼1% or more. The relatively strong [C II] emission is consistent with our sources being dominated by star formation powered photo-dissociation regions, extending to kiloparsec scales. We suggest that the star formation mode in these systems follows a Schmidt-Kennicutt law similar to local systems, but at a much higher rate due to molecular gas surface densities 10-100 times that of local star-forming systems. The source of the high molecular gas surface densities may be the infall of neutral gas from the cosmic web. In addition to the high [C II]/FIR values, we alsomore » find high [C II]/PAH ratios and, in at least one source, a cool dust temperature. This source, SWIRE 4-5, bears a resemblance in these diagnostics to shocked regions of Stephan's Quintet, suggesting that another mode of [C II] excitation in addition to normal photoelectric heating may be contributing to the observed [C II] line.« less
Authors:
 [1] ; ; ; ;  [2] ;  [3] ;  [4] ;  [5]
  1. National Radio Astronomy Observatory, Charlottesville, VA 22903 (United States)
  2. Center for Radiophysics and Space Research, Cornell University, Ithaca, NY 14853 (United States)
  3. Department of Astronomy, Cornell University, Ithaca, NY 14853 (United States)
  4. California Institute of Technology, Mail Code 301-17, 1200 East California Boulevard, Pasadena, CA 91125 (United States)
  5. University of Oxford, Oxford Astrophysics, Denys Wilkinson Building, Keble Road, Oxford, OX1 3RH (United Kingdom)
Publication Date:
OSTI Identifier:
22364553
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 799; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CARBON IONS; DENSITY; DISSOCIATION; EFFICIENCY; EXCITATION; FAR INFRARED RADIATION; GALAXIES; MULTIPARTICLE SPECTROMETERS; PHOTOMETRY; POLYCYCLIC AROMATIC HYDROCARBONS; RED SHIFT; STAR EVOLUTION; STARS; UNIVERSE