Dissecting the stellar mass-SFR correlation in z=1 star-forming disk galaxies

TL;DR

This study investigates the tight correlation between stellar mass and star formation rate in z=1 disk galaxies, revealing that the correlation is influenced by galaxy structure, color, and gas content, with implications for understanding galaxy evolution.

Contribution

It demonstrates that the mass-SFR correlation is tighter when using H-band luminosity and identifies key factors affecting scatter, refining the intrinsic slope of the main sequence.

Findings

The correlation for disk galaxies has a scatter of 0.19 dex when using H-band luminosity.

Most of the scatter is due to real physical variations, not measurement errors.

Correcting for biases yields an intrinsic slope close to unity.

Abstract

Using a mass-limited sample of 24um-detected, star-forming galaxies at 0.5<z<1.3, we study the mass-star formation rate (SFR) correlation and its tightness. The correlation is well defined (sigma=0.28dex) for disk galaxies (n_sersic<1.5), while more bulge-dominated objects often have lower specific SFRs. For disk galaxies, a much tighter correlation (sigma=0.19dex) is obtained if the rest-frame H-band luminosity is used instead of stellar mass derived from multicolor photometry. The specific SFR (sSFR) correlates strongly with rest-frame optical colors (hence luminosity-weighted stellar age) and also with clumpiness (which likely reflects the molecular gas fraction). This implies that most of the observed scatter is real, despite its low level, and not dominated by random measurement errors. After correcting for these differential effects a remarkably small dispersion remains (sigma=0.14dex), suggesting that measurement errors in mass or SFR are ~0.10dex, excluding systematic uncertainties. Measurement errors in stellar masses, the thickening of the correlation due to real sSFR variations, and varying completeness with stellar mass, can spuriously bias the derived slope to lower values due to the finite range over which observables (mass and SFR) are available. When accounting for these effects, the intrinsic slope for the main sequence for disk galaxies gets closer to unity.