Galaxy kinematics and mass estimates at z 1 from ionized gas and stars

We compare ionized gas and stellar kinematics of 16 star-forming galaxies (log (M-star/M-circle dot) = 9.7-11.2, SFR =6 - 86 M-circle dot yr(-1)) at z similar to 1 using near-infrared integral field spectroscopy (IFS) of H alpha emission from the KMOS3D (the K-band Multi-Object Spectrograph 3D) survey and optical slit spectroscopy of stellar absorption and gas emission from the LEGA-C (Large Early Galaxy Astrophysics Census) survey. H alpha is dynamically colder than stars, with higher disc rotation velocities (by similar to 45 per cent) and lower disc velocity dispersions (by a factor similar to 2). This is similar to trends observed in the local Universe. We find higher rotational support for H alpha relative to [O II], potentially explaining systematic offsets in kinematic scaling relations found in the literature. Regarding dynamical mass measurements, for six galaxies with cumulative mass profiles from Jeans Anisotropic Multi-Gaussian Expansion (JAM) models the H alpha dynamical mass models agree remarkably well out to similar to 10 kpc for all but one galaxy (average Delta M-dyn(R-e,R-F814W)<0.1 dex). Simpler dynamical mass estimates based on integrated stellar velocity dispersion are less accurate (standard deviation 0.24 dex). Differences in dynamical mass estimates are larger, for example, for galaxies with stronger misalignments of the H alpha kinematic major axis and the photometric position angle, highlighting the added value of IFS observations for dynamics studies. The good agreement between the JAM and the dynamical models based on H alpha kinematics at z similar to 1 corroborates the validity of dynamical mass measurements from H alpha IFS observations, which can be more easily obtained for higher redshift galaxies.