PANCAKE: A Python-based Numerical Color–Magnitude Diagram Analysis Package

Abstract

Stellar populations serve as a fossil record of galaxy formation and evolution, providing crucial information about the history of star formation and galaxy evolution. The color–magnitude diagram (CMD) stands out as the most accurate tool currently available for inferring the star formation histories (SFHs) of nearby galaxies with stellar-resolved multiband data. The launch of new space telescopes, including JWST, EUCLID, and the upcoming CSST and Roman, will significantly increase the number of stellar-resolved galaxies over the next decade. A user-friendly and customizable CMD-fitting package would be valuable for galaxy evolution studies with these data. We have developed the open-source Python-bAsed Numerical Color–magnitude diagram Analysis pacKagE ( pancake ), which is fast and accurate in determining SFHs and stellar population parameters for nearby galaxies. We have validated our method via a series of comprehensive tests. First, pancake performs well on mock data, while the random and systematic uncertainties are quantified. Second, pancake performs well on observational data containing a star cluster and 38 dwarf galaxies (50 fields). Third, the star formation rates (SFRs) from pancake are consistent with the SFRs determined with far-ultraviolet photometry. To ensure compatibility and accuracy, we have included isochrone libraries generated using PARSEC for most of the optical and near-infrared filters used by space telescopes such as the Hubble Space Telescope, JWST, and the upcoming CSST.

Keywords

• Stellar populations
• Galaxy stellar content
• Hertzsprung Russell diagram