Kavli Affiliate: Risa Wechsler
| First 5 Authors: Mithi A. C. de los Reyes, Mithi A. C. de los Reyes, , ,
| Summary:
The stellar masses of galaxies are measured using integrated light via
several methods — however, few of these methods were designed for low-mass
($M_starlesssim10^8rmM_odot$) "dwarf" galaxies, whose properties
(e.g., stochastic star formation, low metallicity) pose unique challenges for
estimating stellar masses. In this work, we quantify the precision and accuracy
at which stellar masses of low-mass galaxies can be recovered using
UV/optical/IR photometry. We use mock observations of 469 low-mass galaxies
from a variety of models, including both semi-empirical models (GRUMPY and
UniverseMachine-SAGA) and cosmological baryonic zoom-in simulations (MARVELous
Dwarfs and FIRE-2), to test literature color-$M_star/L$ relations and
multi-wavelength spectral energy distribution (SED) mass estimators. We
identify a list of "best practices" for measuring stellar masses of low-mass
galaxies from integrated photometry. We find that literature color-$M_star/L$
relations are often unable to capture the bursty star formation histories
(SFHs) of low-mass galaxies, and we develop an updated prescription for stellar
mass based on $g-r$ color that is better able to recover stellar masses for the
bursty low-mass galaxies in our sample (with ~0.1 dex precision). SED fitting
can also precisely recover stellar masses of low-mass galaxies, but this
requires thoughtful choices about the form of the assumed SFH: parametric SFHs
can underestimate stellar mass by as much as ~0.4 dex, while non-parametric
SFHs recover true stellar masses with insignificant offset (-0.03$pm$0.11
dex). Finally, we also caution that non-informative (wide) dust attenuation
priors may introduce $M_star$ uncertainties of up to ~0.6 dex.
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