LEGA-C: analysis of dynamical masses from ionized gas and stellar
  kinematics at z~0.8
  We compare dynamical mass estimates based on spatially extended stellar and
ionized gas kinematics ($\mathrm{M_{dyn,*}}$ and $\mathrm{M_{dyn,eml}}$,
respectively) of 157 star forming galaxies at $0.6\leq z<1$. Compared to
$z\sim0$, these galaxies have enhanced star formation rates, with stellar
feedback likely affecting the dynamics of the gas. We use LEGA-C DR3, the
highest redshift dataset providing sufficiently deep measurements of a
$K_s-$band limited sample. For $\mathrm{M_{dyn,*}}$ we use Jeans Anisotropic
Multi-Gaussian Expansion models. For $\mathrm{M_{dyn,eml}}$ we first fit a
custom model of a rotating exponential disk with uniform dispersion, whose
light is projected through a slit and corrected for beam smearing. We then
apply an asymmetric drift correction based on assumptions common in the
literature to the fitted kinematic components to obtain the circular velocity,
assuming hydrostatic equilibrium. Within the half-light radius,
$\mathrm{M_{dyn,eml}}$ is on average lower than $\mathrm{M_{dyn,*}}$, with a
mean offset of $-0.15\pm0.016$ dex and galaxy-to-galaxy scatter of $0.19$ dex,
reflecting the combined random uncertainty. While data of higher spatial
resolution are needed to understand this small offset, it supports the
assumption that the galaxy-wide ionized gas kinematics do not predominantly
originate from disruptive events such as star formation driven outflows.
However, a similar agreement can be obtained without modeling from the
integrated emission line dispersions for axis ratios $q<0.8$. This suggests
that our current understanding of gas kinematics is not sufficient to
efficiently apply asymmetric drift corrections to improve dynamical mass
estimates compared to observations lacking the $S/N$ required for spatially
extended dynamics.
