A turnover in the galaxy main sequence of star formation at M ∼ 1010 M for redshifts z < 1.3

Nicholas Lee, D. B. Sanders, Caitlin M. Casey, Sune Toft, N. Z. Scoville, Chao Ling Hung, Emeric Le Floc'H, Olivier Ilbert, H. Jabran Zahid, Hervé Aussel, Peter Capak, Jeyhan S. Kartaltepe, Lisa J. Kewley, Yanxia Li, Kevin Schawinski, Kartik Sheth, Quanbao Xiao

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    183 Citations (Scopus)

    Abstract

    The relationship between galaxy star formation rates (SFRs) and stellar masses (M ) is reexamined using a mass-selected sample of 62,000 star-forming galaxies at z ≤ 1.3 in the COSMOS 2 deg2 field. Using new far-infrared photometry from Herschel-PACS and SPIRE and Spitzer-MIPS 24 μm, along with derived infrared luminosities from the NRK method based on galaxies' locations in the restframe color-color diagram (NUV-r) versus (r-K), we are able to more accurately determine total SFRs for our complete sample. At all redshifts, the relationship between median SFR and M follows a power law at low stellar masses, and flattens to nearly constant SFR at high stellar masses. We describe a new parameterization that provides the best fit to the main sequence and characterizes the low mass power-law slope, turnover mass, and overall scaling. The turnover in the main sequence occurs at a characteristic mass of about M 0 1010 M at all redshifts. The low mass power-law slope ranges from 0.9-1.3 and the overall scaling rises in SFR as a function of (1 + z)4.12 ± 0.10. A broken power-law fit below and above the turnover mass gives relationships of below the turnover mass and above the turnover mass. Galaxies more massive than M ≳ 1010 M have a much lower average specific star formation rate (sSFR) than would be expected by simply extrapolating the traditional linear fit to the main sequence found for less massive galaxies.

    Original languageEnglish
    Article number80
    JournalAstrophysical Journal
    Volume801
    Issue number2
    DOIs
    Publication statusPublished - 10 Mar 2015

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