Probing Cosmic Conformity in Local Volume Dwarf Galaxies with Star Formation Histories from CMDs and SEDs

Star Formation Histories (SFHs) reveal physical processes that influence how galaxies form their stellar mass. We compare the SFHs of a sample of 39 nearby (D < 4 Mpc) galaxies from the ACS Nearby Galaxy Survey Treasury (ANGST), inferred from the Color Magnitude Diagrams (CMDs) of individually resolved stars by Johnson et al (2013 ApJ 772, 8), with SFHs reconstructed from our broad-band Spectral Energy Distribution (SED) fitting. When comparing individual SFHs, we introduce metrics for evaluating SFH reconstruction techniques. Although we find that SED-based SFH reconstructions are uncertain at large lookback times, both methods reveal that the median SFH of all galaxies in the sample shows special epochs of star formation at lookback times of 2, 5, and 6 Gyr. Our results motivate further study of potential synchronized star formation rejuvenation and quenching events across the Local Volume as well as the development of a hybrid method to combine the strengths of CMD- and SED-based approaches, which have complementary systematics.