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

Abstract

We investigate the star formation rate (SFR) and stellar mass, M_*, relation of a star-forming (SF) galaxy (SFG) sample in the XMM-LSS field to z ∼ 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 probability-distribution-function uncertainty. Applying an SF selection using the D4000 index, we find evidence for strong evolution in the normalization of the SFR-M_* relation out to z ∼ 3 and a roughly constant slope of (SFR ∝ M_*^{α }) α = 0.69 ± 0.02 to z ∼ 1.7. We find this increases close to unity towards z ∼ 2.65. Alternatively, if we apply a colour selection, we find a distinct turnover in the SFR-M_* relation between 0.7 ≲ z ≲ 2.0 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 ∝ (1 + z)^2.60 at log₁₀(M_*/M_⊙) ∼ 10.5, out to z ≲ 2.4 with an observed flattening beyond z ∼ 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.