Weighing Galaxy Disks with the Baryonic Tully-Fisher Relation
  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.
