The evolving relation between star-formation rate and stellar mass in the VIDEO Survey since $z=3$

TL;DR

This study examines how the relationship between star-formation rate and stellar mass in galaxies has evolved since redshift 3, revealing a consistent slope and evolving normalization, with implications for galaxy growth models.

Contribution

It provides a detailed analysis of the SFR-$M_*$ relation evolution up to z=3 using VIDEO survey data and adapts SED fitting to account for redshift uncertainties.

Findings

Strong evolution in SFR-$M_*$ normalization up to z=3

Constant slope of ~0.69 to z~1.7, increasing near unity at z~2.65

Evolution of specific SFR proportional to (1+z)^{2.60}

Abstract

We investigate the star-formation rate (SFR) and stellar mass ($M_*$) relation of a star-forming (SF) galaxy sample in the XMM-LSS field to $z\sim 3.0$ using the near-infrared data from the VISTA Deep Extragalactic Observations (VIDEO) survey. Combining VIDEO with broad-band photometry, we use the SED fitting algorithm CIGALE to derive SFRs and $M_*$ and have adapted it to account for the full photometric redshift PDF uncertainty. Applying a SF selection using the D4000 index, we find evidence for strong evolution in the normalisation of the SFR-$M_*$ relation out to $z\sim 3$ and a roughly constant slope of (SFR $\propto M_*^{\alpha}$) $\alpha=0.69\pm0.02$ to $z\sim 1.7$. We find this increases close to unity toward $z\sim2.65$. Alternatively, if we apply a colour selection, we find a distinct turnover in the SFR-$M_*$ relation between $0.7\lesssim z\lesssim2.0$ at the high mass end, and suggest that this is due to an increased contamination from passive galaxies. We find evolution of the specific SFR $\propto(1+z)^{2.60}$ at $\log(M_*)\sim$10.5, out to $z\lesssim2.4$ with an observed flattening beyond $z\sim$ 2 with increased stellar mass. Comparing to a range of simulations we find the analytical scaling relation approaches, that invoke an equilibrium model, a good fit to our data, suggesting that a continual smooth accretion regulated by continual outflows may be a key driver in the overall growth of SFGs.