Mass-to-Light versus Color Relations for Dwarf Irregular Galaxies

TL;DR

This paper establishes new mass-to-light versus color relations for dwarf irregular galaxies based on multi-wavelength data, enabling stellar mass estimates where other methods are unavailable, and explores metallicity effects on these relations.

Contribution

It introduces new MLCRs for dwarf irregular galaxies derived from spectral energy distribution fitting, highlighting their shallower slope and metallicity dependence compared to spiral galaxy relations.

Findings

MLCRs are shallower than those for spiral galaxies.

Indications of steepening MLCRs with higher metallicity.

Relations enable stellar mass estimation from colors in dIrr galaxies.

Abstract

We have determined new relations between $UBV$ colors and mass-to-light ratios ($M/L$) for dwarf irregular (dIrr) galaxies, as well as for transformed $g^\prime - r^\prime$. These $M/L$ to color relations (MLCRs) are based on stellar mass density profiles determined for 34 LITTLE THINGS dwarfs from spectral energy distribution fitting to multi-wavelength surface photometry in passbands from the FUV to the NIR. These relations can be used to determine stellar masses in dIrr galaxies for situations where other determinations of stellar mass are not possible. Our MLCRs are shallower than comparable MLCRs in the literature determined for spiral galaxies. We divided our dwarf data into four metallicity bins and found indications of a steepening of the MLCR with increased oxygen abundance, perhaps due to more line blanketing occurring at higher metallicity.