From light to baryonic mass: the effect of the stellar mass-to-light ratio on the Baryonic Tully-Fisher relation

TL;DR

This study examines how the stellar mass-to-light ratio affects the Baryonic Tully-Fisher relation in 32 galaxies, revealing a slope close to 3 and providing constraints for galaxy formation models.

Contribution

It offers a detailed analysis of the BTFr's statistical properties using multiple methods to estimate stellar mass and kinematic measures, improving understanding of galaxy dynamics.

Findings

BTFr slope is approximately 3, close to the theoretical expectation.

Intrinsic scatter of the BTFr is very small, indicating a tight relation.

Results provide observational constraints for galaxy formation theories.

Abstract

In this paper we investigate the statistical properties of the Baryonic Tully-Fisher relation (BTFr) for a sample of 32 galaxies with accurate distances based on Cepheids and/or TRGB stars. We make use of homogeneously analysed photometry in 18 bands ranging from the FUV to 160 $\mu$m, allowing us to investigate the effect of the inferred stellar mass-to-light ratio $\Upsilon_{*}$ on the statistical properties of the BTFr. Stellar masses of our sample galaxies are derived with four different methods based on full SED-fitting, studies of stellar dynamics, near-infrared colours, and the assumption of the same $\Upsilon_{*}^{[3.6]}$ for all galaxies. In addition, we use high-quality, resolved HI kinematics to study the BTFr based on three kinematic measures: $W_{50}^{i}$ from the global HI profile, and $V_{max}$ and $V_{flat}$ from the rotation curve. We find the intrinsic perpendicular scatter, or tightness, of our BTFr to be $\sigma_{\perp} = 0.026 \pm 0.013$ dex, consistent with the intrinsic tightness of the 3.6 $\mu$m luminosity-based TFr. However, we find the slope of the BTFr to be $2.99 \pm 0.2$ instead of $3.7 \pm 0.1$ for the luminosity-based TFr at 3.6 $\mu$m. We use our BTFr to place important observational constraints on theoretical models of galaxy formation and evolution by making comparisons with theoretical predictions based on either the $\Lambda$CDM framework or modified Newtonian dynamics.