2015ApJ...802...18M

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 ∝ V_f⁴over 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_☉/L_☉ in K_s and 0.45 M_☉/L_☉ at 3.6 µm. There is only modest intrinsic scatter (∼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.