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

Abstract

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 _⊙ at z > 4. The evolution of the correlation is well described by {log} {SFR}=(0.80+/- 0.029-0.017+/- 0.010× {t}_univ}) {log} {M}_* -(6.487+/- 0.282-0.039+/- 0.008× {t}_univ}), where t _univ is the age of the universe in Gyr.