Evolution of Intrinsic Scatter in the SFR-Stellar Mass Correlation at 0.5<z<3

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_* ~ 10^7M_⊙, 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 10^7M_⊙.