EVOLUTION OF INTRINSIC SCATTER IN THE SFR–STELLAR MASS CORRELATION AT 0.5 < z < 3

Abstract

ABSTRACT We present estimates of intrinsic scatter in the star formation rate (SFR)–stellar mass (M *) correlation in the redshift range 0.5 < z < 3.0 ?> and in the mass range 10 7 < M * < 10 11 ?> M ⊙. We utilize photometry in the Hubble Ultradeep Field (HUDF12) and Ultraviolet Ultra Deep Field (UVUDF) campaigns and CANDELS/GOODS-S and estimate SFR, M * from broadband spectral energy distributions and the best-available redshifts. The maximum depth of the UDF photometry (F160W 29.9 AB, 5σ depth) probes the SFR–M * correlation down to M * ∼ ?> 107 M ⊙, a factor of 10–100× lower in M * than previous studies, and comparable to dwarf galaxies in the local universe. We find the slope of the SFR–M * relationship to be near unity at all redshifts and the normalization to decrease with cosmic time. We find a moderate increase in intrinsic scatter with cosmic time from 0.2 to 0.4 dex across the epoch of peak cosmic star formation. None of our redshift bins show a statistically significant increase in intrinsic scatter at low mass. However, it remains possible that intrinsic scatter increases at low mass on timescales shorter than ∼100 Myr. Our results are consistent with a picture of gradual and self-similar assembly of galaxies across more than three orders of magnitude in stellar mass from as low as 107 M ⊙.