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Title: The intrinsic scatter along the main sequence of star-forming galaxies at z ∼ 0.7

A sample of 12,614 star-forming galaxies (SFGs) with stellar mass >10{sup 9.5} M {sub ☉} between 0.6 < z < 0.8 from COSMOS is selected to study the intrinsic scatter of the correlation between star formation rate (SFR) and stellar mass. We derive SFR from ultraviolet (UV) and infrared (IR) luminosities. A stacking technique is adopted to measure IR emission for galaxies undetected at 24 μm. We confirm that the slope of the mass-SFR relation is close to unity. We examine the distributions of specific SFRs (SSFRs) in four equally spaced mass bins from 10{sup 9.5} M {sub ☉} to 10{sup 11.5} M {sub ☉}. Different models are used to constrain the scatter of SSFR for lower mass galaxies that are mostly undetected at 24 μm. The SFR scatter is dominated by the scatter of UV luminosity and gradually that of IR luminosity at increasing stellar mass. We derive SSFR dispersions of 0.18, 0.21, 0.26, and 0.31 dex with a typical measurement uncertainty of ≲ 0.01 dex for the four mass bins. Interestingly, the scatter of the mass-SFR relation seems not constant in the sense that the scatter in SSFR is smaller for SFGs of stellar mass <10{sup 10.5} Mmore » {sub ☉}. If confirmed, this suggests that the physical processes governing star formation become systematically less violent for less massive galaxies. The SSFR distribution for SFGs with intermediate mass 10{sup 10}-10{sup 10.5} M {sub ☉} is characterized by a prominent excess of intense starbursts in comparison with other mass bins. We argue that this feature reflects that both violent (e.g., major/minor mergers) and quiescent processes are important in regulating star formation in this intermediate-mass regime.« less
Authors:
;  [1] ;  [2]
  1. Purple Mountain Observatory, Chinese Academy of Sciences, 2 West-Beijing Road, Nanjing 210008 (China)
  2. Department of Physics and Astronomy, University of Iowa, Van Allen Hall, Iowa City, IA 52242 (United States)
Publication Date:
OSTI Identifier:
22342038
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 778; 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; AUGMENTATION; COMPARATIVE EVALUATIONS; CORRELATIONS; DISPERSIONS; DISTRIBUTION; EMISSION; EVOLUTION; GALAXIES; LUMINOSITY; MASS; SPACE; STAR EVOLUTION; STARS; ULTRAVIOLET RADIATION; UNIVERSE