A galactic weigh-in: mass models of SINGS galaxies using chemospectrophotometric galactic evolution models

TL;DR

This paper uses chemo-spectrophotometric models to determine radially varying mass-to-light ratios in galaxies, improving stellar mass estimates and understanding of galaxy structure and dark matter distribution.

Contribution

It introduces a method applying chemo-spectrophotometric models for radial mass-to-light ratio estimation, enhancing galaxy mass modeling accuracy over traditional color-based methods.

Findings

CSPE models reliably estimate stellar disc masses across spectral bands.

Color index vs. mass-to-light ratio relation is unreliable for young stellar populations.

Discs are compatible with maximum disc hypothesis with proper bulge/disc decomposition.

Abstract

The baryonic mass-to-light ratio used to perform the photometry-to-mass conversion has a tremendous influence on the measurement of the baryonic content and distribution, as well as on the determination of the dark halo parameters. Since numerous clues hint at an inside-out formation process for galaxies, a radius-dependant mass-to-light ratio is needed to physically represent the radially varying stellar population. In this article, we use chemo-spectrophotometric galactic evolution (CSPE) models to determine the mass-to-light ratio for a wide range of masses and sizes in the scenario of an inside-out formation process by gas accretion. We apply our method on a SINGS subsample of ten spiral and dwarf galaxies for stellar bands covering from the UV to the MIR. The CSPE models prove to be a good tool to weight the different photometric bands in order to obtain consistent stellar discs' masses regardless of the spectral band used. On the other hand, we show that colour index vs. the mass-to-light ratio relation is an imperfect tool to assign masses to young stellar populations because of the degeneracy affecting mass-to-light ratio in all bands at low colour index. Resulting discs from our analysis are compatible with the maximum disc hypothesis provided that adequate bulge/disc decomposition is performed and correction for the presence of a bar is not neglected since it disturbs the internal disc kinematics. Disc-mass models including mass-to-light ratio-as a free parameter as well as models using our physically motivated radial variation of mass-to-light ratio are presented and discussed for each galaxy.