Weighing Galaxy Disks with the Baryonic Tully-Fisher Relation

TL;DR

This paper demonstrates that the Baryonic Tully-Fisher relation provides a reliable, nearly universal method for estimating stellar masses of disk galaxies, with consistent results across different methods and minimal scatter.

Contribution

It introduces a consistent calibration of the stellar mass scale using the BTFR, confirming its universality and negligible intrinsic scatter across a wide mass range.

Findings

BTFR follows $M_b \,\propto\, V_f^4$ over six decades in mass

Intrinsic scatter in the BTFR is negligible, indicating a universal IMF

Near-infrared mass-to-light ratios are nearly constant at 0.57 and 0.45 M_sun/L_sun

Abstract

We estimate the stellar masses of disk galaxies with two independent methods: a photometrically self-consistent color$-$mass-to-light ratio relation (CMLR) from population synthesis models, and the Baryonic Tully-Fisher relation (BTFR) calibrated by gas rich galaxies. These two methods give consistent results. The CMLR correctly converts distinct Tully-Fisher relations in different bands into the same BTFR. The BTFR is consistent with $M_b \propto V_f^4$ over nearly six decades in mass, with no hint of a change in slope over that range. The intrinsic scatter in the BTFR is negligible, implying that the IMF of disk galaxies is effectively universal. The gas rich BTFR suggests an absolute calibration of the stellar mass scale that yields nearly constant mass-to-light ratios in the near-infrared (NIR): $0.57\;M_{\odot}/L_{\odot}$ in $K_s$ and $0.45\;M_{\odot}/L_{\odot}$ at $3.6\mu$. There is only modest intrinsic scatter ($\sim 0.12$ dex) about these typical values. There is no discernible variation with color or other properties: the NIR luminosity is a good tracer of stellar mass.