A turnover in the galaxy main sequence of star formation at M*∼ 10¹⁰ M☉ for redshifts z< 1.3
Date
2015-03-05
Authors
Lee, Nicholas
Sanders, D. B.
Casey, Caitlin M.
Toft, Sune
Scoville, N. Z.
Hung, Chao-Ling
Le Floc'h, Emeric
Ilbert, Olivier
Zahid, H. Jabran
Aussel, Hervé
Journal Title
Journal ISSN
Volume Title
Publisher
IOP Publishing
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 deg²field. Using new
far-infrared photometry from Herschel-PACS and SPIRE and Spitzer-MIPS 24μm, 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 M0 ∼ 10¹⁰ Mʘ 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 SFR ∝ M⁰˙⁸⁸±⁰˙⁰⁶ ∗ below the turnover mass and SFR ∝ M⁰˙²⁷±⁰˙⁰⁴ ∗ 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.
Description
Keywords
galaxies: evolution, galaxies: high-redshift, galaxies: star formation
Citation
Collections
Source
The Astrophysical Journal
Type
Journal article