Stellar Mass-to-light Ratios: Composite Bulge+Disk Models and the Baryonic Tully-Fisher Relation

TL;DR

This paper develops composite bulge+disk stellar population models to accurately estimate galaxy mass-to-light ratios from multi-wavelength colors, improving the baryonic Tully-Fisher relation's linearity and reducing scatter.

Contribution

It introduces a new composite bulge+disk $$ model that incorporates optical and near-IR colors to better estimate stellar mass-to-light ratios.

Findings

Using actual bulge and disk colors constrains $$ more accurately.

Applying these models improves the linearity and slope of the baryonic Tully-Fisher relation.

The scatter in the relation is reduced by 4%.

Abstract

We present stellar population models to calculate the mass-to-light ratio ($\Upsilon_*$) based on galaxy's colors ranging from $GALEX$ FUV to Spitzer IRAC1 at 3.6$\mu$m. We present a new composite bulge+disk $\Upsilon_*$ model that considers the varying contribution from bulges and disks based on their optical and near-IR colors. Using these colors, we build plausible star formation histories and chemical enrichment scenarios based on the star formation rate-stellar mass and mass-metallicity correlations for star-forming galaxies. The most accurate prescription is to use the actual colors for the bulge and disk components to constrain $\Upsilon_*$; however, a reasonable bulge+disk model plus total color only introduces 5% more uncertainty. Full bulge+disk $\Upsilon_*$ prescriptions applied to the baryonic TF relation improves the linearity of the correlation, increases the slope and reduces the total scatter by 4%.