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A Turnover in the Galaxy Main Sequence of Star Formation at $M_* \sim 10^10 M_ødot$ for Redshifts $z < 1.3$

, , , , , , , , , , , , , , , , and . (2015)cite arxiv:1501.01080Comment: 16 pages, 7 figures. Accepted for publication in ApJ.

Abstract

The relationship between galaxy star formation rates (SFR) and stellar masses ($M_\ast$) is re-examined using a mass-selected sample of $\sim$62,000 star-forming galaxies at $z 1.3$ in the COSMOS 2-deg$^2$ field. Using new far-infrared photometry from $Herschel$-PACS and SPIRE and $Spitzer$-MIPS 24 $\mu$m, along with derived infrared luminosities from the NRK method based on galaxies' locations in the restframe color-color diagram $(NUV - r)$ vs. $(r - K)$, we are able to more accurately determine total SFRs for our complete sample. At all redshifts, the relationship between median $SFR$ and $M_\ast$ 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 $M_0 10^10 M_ødot$ 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 $SFR M_*^0.88 \pm 0.06$ below the turnover mass and $SFR M_*^0.27 0.04$ above the turnover mass. Galaxies more massive than $M_10^10\ M_\rm ødot$ have on average, a much lower 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

[1501.01080] A Turnover in the Galaxy Main Sequence of Star Formation at $M_{*} \sim 10^{10} M_{\odot}$ for Redshifts $z &lt; 1.3$

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