The EDGE-CALIFA survey: validating stellar dynamical mass models with CO
  kinematics
  Deriving circular velocities of galaxies from stellar kinematics can provide
an estimate of their total dynamical mass, provided a contribution from the
velocity dispersion of the stars is taken into account. Molecular gas (e.g.,
CO) on the other hand, is a dynamically cold tracer and hence acts as an
independent circular velocity estimate without needing such a correction. In
this paper we test the underlying assumptions of three commonly used dynamical
models, deriving circular velocities from stellar kinematics of 54 galaxies
(S0-Sd) that have observations of both stellar kinematics from the CALIFA
survey, and CO kinematics from the EDGE survey. We test the Asymmetric Drift
Correction (ADC) method, as well as Jeans, and Schwarzschild models. The three
methods each reproduce the CO circular velocity at 1Re to within 10%. All three
methods show larger scatter (up to 20%) in the inner regions (R < 0.4Re) which
may be due to an increasingly spherical mass distribution (which is not
captured by the thin disk assumption in ADC), or non-constant stellar M/L
ratios (for both the JAM and Schwarzschild models). This homogeneous analysis
of stellar and gaseous kinematics validates that all three models can recover
Mdyn at 1Re to better than 20%, but users should be mindful of scatter in the
inner regions where some assumptions may break down.
