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Title: The role of galaxy interaction in the SFR-M {sub *} relation: characterizing morphological properties of Herschel-selected galaxies at 0.2 < z < 1.5

Galaxy interactions/mergers have been shown to dominate the population of IR-luminous galaxies (L {sub IR} ≳ 10{sup 11.6} L {sub ☉}) in the local universe (z ≲ 0.25). Recent studies based on the relation between galaxies' star formation rates and stellar mass (the SFR-M {sub *} relation or the {sup g}alaxy main sequence{sup )} have suggested that galaxy interaction/mergers may only become significant when galaxies fall well above the galaxy main sequence. Since the typical SFR at a given M {sub *} increases with redshift, the existence of the galaxy main sequence implies that massive, IR-luminous galaxies at high z may not necessarily be driven by galaxy interactions. We examine the role of galaxy interactions in the SFR-M {sub *} relation by carrying out a morphological analysis of 2084 Herschel-selected galaxies at 0.2 < z < 1.5 in the COSMOS field. Using a detailed visual classification scheme, we show that the fraction of 'disk galaxies' decreases and the fraction of 'irregular' galaxies increases systematically with increasing L {sub IR} out to z ≲ 1.5 and z ≲ 1.0, respectively. At L {sub IR} >10{sup 11.5} L {sub ☉}, ≳ 50% of the objects show evident features of strongly interacting/merger systems,more » where this percentage is similar to the studies of local IR-luminous galaxies. The fraction of interacting/merger systems also systematically increases with the deviation from the SFR-M {sub *} relation, supporting the view that galaxies falling above the main sequence are more dominated by mergers than the main-sequence galaxies. Meanwhile, we find that ≳ 18% of massive IR-luminous 'main-sequence galaxies' are classified as interacting systems, where this population may not evolve through the evolutionary track predicted by a simple gas exhaustion model.« less
Authors:
; ; ; ; ; ; ; ; ;  [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7]
  1. Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)
  2. Spitzer Science Center, MS 314-6, California Institute of Technology, Pasadena, CA 91125 (United States)
  3. National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States)
  4. UMR AIM (CEA-UP7-CNRS), CEA-Saclay, Orme des Merisiers, bât. 709, F-91191 Gif-sur-Yvette Cedex (France)
  5. NASA Ames Research Center, Moffett Field, CA (United States)
  6. California Institute of Technology, MC 249-17, 1200 East California Boulevard, Pasadena, CA 91125 (United States)
  7. University of Sussex, Department of Physics and Astronomy, Pevensey 2 Building, Falmer, Brighton BN1 9QH, Sussex (United Kingdom)
Publication Date:
OSTI Identifier:
22341921
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 778; 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; CLASSIFICATION; EVOLUTION; GALAXIES; INFRARED RADIATION; INTERACTIONS; LUMINOSITY; MASS; RED SHIFT; STARS; UNIVERSE