The Impact of Star Formation Histories on Stellar Mass Estimation: Implications from the Local Group Dwarf Galaxies

Building on the relatively accurate star formation histories (SFHs) and metallicity evolution of 40 Local Group (LG) dwarf galaxies derived from resolved color-magnitude diagram modeling, we carried out a comprehensive study of the influence of SFHs, metallicity evolution, and dust extinction on the UV-to-near-IR color-mass-to-light ratio (color-{log}{{{\Upsilon }}}_\star (λ)) distributions and M _⋆ estimation of local universe galaxies. We find that (1) the LG galaxies follow color-{log}{{{\Upsilon }}}_\star (λ) relations that fall in between the ones calibrated by previous studies; (2) optical color-{log}{{{\Upsilon }}}_\star (λ) relations at higher [M/H] are generally broader and steeper; (3) the SFH “concentration” does not significantly affect the color-{log}{{{\Upsilon }}}_\star (λ) relations; (4) light-weighted ages < {age}{> }_λ and metallicities < [{{M}}/{{H}}]{> }_λ together constrain {log}{{{\Upsilon }}}_\star (λ) with uncertainties ranging from ≲0.1 dex for the near-IR up to 0.2 dex for the optical passbands; (5) metallicity evolution induces significant uncertainties to the optical but not near-IR {{{\Upsilon }}}_\star (λ) at a given < {age}{> }_λ and < [{{M}}/{{H}}]{> }_λ ; (6) the V band is the ideal luminance passband for estimating {{{\Upsilon }}}_\star (λ) from single colors, because the combinations of {{{\Upsilon }}}_\star (V) and optical colors such as B - V and g - r exhibit the weakest systematic dependences on SFHs, metallicities, and dust extinction; and (7) without any prior assumption on SFHs, M _⋆ is constrained with biases ≲0.3 dex by the optical-to-near-IR SED fitting. Optical passbands alone constrain M _⋆ with biases ≲0.4 dex (or ≲0.6 dex) when dust extinction is fixed (or variable) in SED fitting. SED fitting with monometallic SFH models tends to underestimate M _⋆ of real galaxies. M _⋆ tends to be overestimated (or underestimated) at the youngest (or oldest) < {age}{> }_{mass}.