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

Abstract

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– ( λ )) distributions and M ⋆ estimation of local universe galaxies. We find that (1) the LG galaxies follow color– ( λ ) relations that fall in between the ones calibrated by previous studies; (2) optical color– ( λ ) relations at higher [M/H] are generally broader and steeper; (3) the SFH “concentration” does not significantly affect the color– ( λ ) relations; (4) light-weighted ages  and metallicities  together constrain ( 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 ( λ ) at a given  and ; (6) the V band is the ideal luminance passband for estimating ( λ ) from single colors, because the combinations of ( 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) .