Galaxy observations are influenced by many physical parameters : stellar masses , star formation rates ( SFRs ) , star formation histories ( SFHs ) , metallicities , dust , black hole activity , and more .
As a result , inferring accurate physical parameters requires high-dimensional models which capture or marginalize over this complexity .
Here we re-assess inferences of galaxy stellar masses and SFRs using the 14-parameter physical model Prospector- \alpha built in the Prospector Bayesian inference framework .
We fit the photometry of 58,461 galaxies from the 3D-HST catalogs at 0.5 < z < 2.5 .
The resulting stellar masses are \sim 0.1 - 0.3 dex larger than the fiducial masses while remaining consistent with dynamical constraints .
This change is primarily due to the systematically older SFHs inferred with Prospector .
The SFRs are \sim 0.1 - 1 + dex lower than UV+IR SFRs , with the largest offsets caused by emission from “ old ” ( t > 100 Myr ) stars .
These new inferences lower the observed cosmic star formation rate density by \sim 0.2 dex and increase the observed stellar mass growth by \sim 0.1 dex , finally bringing these two quantities into agreement and implying an older , more quiescent Universe than found by previous studies at these redshifts .
We corroborate these results by showing that the Prospector- \alpha SFHs are both more physically realistic and are much better predictors of the evolution of the stellar mass function .
Finally , we highlight examples of observational data which can break degeneracies in the current model ; these observations can be incorporated into priors in future models to produce new & more accurate physical parameters .