How to Measure Galaxy Star Formation Histories II: Nonparametric Models

Understand

Nonparametric star formation histories (SFHs) have long promised to be the `gold standard' for galaxy spectral energy distribution (SED) modeling as they are flexible enough to describe the full diversity of SFH shapes, whereas parametric models rule out a significant fraction of these shapes {\it a priori}.

• However, this flexibility is not fully constrained even with high-quality observations, making it critical to choose a well-motivated prior.
• Here, we use the SED-fitting code \texttt{Prospector} to explore the effect of different nonparametric priors by fitting SFHs to mock UV-IR photometry generated from a diverse set of input SFHs.
• First, we confirm that nonparametric SFHs recover input SFHs with less bias and return more accurate errors than do parametric SFHs.