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Title: The rest-frame submillimeter spectrum of high-redshift, dusty, star-forming galaxies

We present the average rest-frame spectrum of high-redshift dusty, star-forming galaxies from 250 to 770 GHz. This spectrum was constructed by stacking Atacama Large Millimeter/submillimeter Array (ALMA) 3 mm spectra of 22 such sources discovered by the South Pole Telescope and spanning z = 2.0-5.7. In addition to multiple bright spectral features of {sup 12}CO, [C I], and H{sub 2}O, we also detect several faint transitions of {sup 13}CO, HCN, HNC, HCO{sup +}, and CN, and use the observed line strengths to characterize the typical properties of the interstellar medium of these high-redshift starburst galaxies. We find that the {sup 13}CO brightness in these objects is comparable to that of the only other z > 2 star-forming galaxy in which {sup 13}CO has been observed. We show that the emission from the high-critical density molecules HCN, HNC, HCO{sup +}, and CN is consistent with a warm, dense medium with T {sub kin} ∼ 55 K and n{sub H{sub 2}}≳10{sup 5.5} cm{sup –3}. High molecular hydrogen densities are required to reproduce the observed line ratios, and we demonstrate that alternatives to purely collisional excitation are unlikely to be significant for the bulk of these systems. We quantify the average emission frommore » several species with no individually detected transitions, and find emission from the hydride CH and the linear molecule CCH for the first time at high redshift, indicating that these molecules may be powerful probes of interstellar chemistry in high-redshift systems. These observations represent the first constraints on many molecular species with rest-frame transitions from 0.4 to 1.2 mm in star-forming systems at high redshift, and will be invaluable in making effective use of ALMA in full science operations.« less
Authors:
;  [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [8] ; ;  [9] ;  [10] ; ;  [11] ;  [12] ;  [13] ;  [14] ;  [15] ;  [16] ;
  1. Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)
  2. University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104 (United States)
  3. European Southern Observatory, Alonso de Cordova 3107, Casilla 19001 Vitacura Santiago (Chile)
  4. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
  5. Laboratoire AIM-Paris-Saclay, CEA/DSM/Irfu-CNRS-Université Paris Diderot, CEA-Saclay, Orme des Merisiers, F-91191 Gif-sur-Yvette (France)
  6. Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States)
  7. Cavendish Laboratory, University of Cambridge, JJ Thompson Ave, Cambridge CB3 0HA (United Kingdom)
  8. Department of Physics and Astronomy, University of Missouri, 5110 Rockhill Road, Kansas City, MO 64110 (United States)
  9. Kavli Institute for Cosmological Physics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States)
  10. Dalhousie University, Halifax, Nova Scotia (Canada)
  11. European Southern Observatory, Karl Schwarzschild Straße 2, D-85748 Garching (Germany)
  12. Department of Physics, University of California, One Shields Avenue, Davis, CA 95616 (United States)
  13. Department of Astronomy, University of Florida, Gainesville, FL 32611 (United States)
  14. Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom)
  15. Department of Physics, McGill University, 3600 Rue University, Montreal, Quebec H3A 2T8 (Canada)
  16. Department of Physics, University of California, Berkeley, CA 94720 (United States)
Publication Date:
OSTI Identifier:
22357075
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 785; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BRIGHTNESS; CARBON NITRIDES; COMPARATIVE EVALUATIONS; CYANIDES; DENSITY; EMISSION; EXCITATION; GALAXIES; GHZ RANGE; HYDRIDES; HYDROCYANIC ACID; HYDROGEN; LIMITING VALUES; MOLECULES; RED SHIFT; SPECTRA; STAR EVOLUTION; STARS; TELESCOPES; WATER