The SFR-M _∗ Correlation Extends to Low Mass at High Redshift

To achieve a fuller understanding of galaxy evolution, SED fitting can be used to recover quantities beyond stellar masses (M _∗) and star formation rates (SFRs). We use star formation histories (SFHs) reconstructed via the Dense Basis method of Iyer & Gawiser for a sample of 17,873 galaxies at 0.5 < z < 6 in the Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey GOODS-S field to study the nature and evolution of the SFR-M _∗ correlation. The reconstructed SFHs represent trajectories in SFR-M _∗ space, enabling us to study galaxies at epochs earlier than observed by propagating them backward in time along these trajectories. We study the SFR-M _∗ correlation at z = 1, 2, 3, 4, 5, 6 using both direct fits to galaxies observed at those epochs and SFR-M _∗ trajectories of galaxies observed at lower redshifts. The SFR-M _∗ correlations obtained using the two approaches are found to be consistent with each other through a K-S test. Validation tests using SFHs from semi-analytic models and cosmological hydrodynamical simulations confirm the sensitivity of the method to changes in the slope, normalization, and shape of the SFR-M _∗ correlation. This technique allows us to further probe the low-mass regime of the correlation at high z by ∼1 dex and over an effective volume of ∼10×larger than possible with just direct fits. We find that the SFR-M _∗ correlation is consistent with being linear down to M _∗ ∼ 10⁶ M _o at z > 4. The evolution of the correlation is well described by , where t _univ is the age of the universe in Gyr.