LEGA-C: analysis of dynamical masses from ionized gas and stellar kinematics at z~0.8

Abstract

We compare dynamical mass estimates based on spatially extended stellar and ionized gas kinematics (${\mathrm{M}}_{\mathrm{dyn},\ast }$ and ${\mathrm{M}}_{\mathrm{dyn},\mathrm{eml}}$, respectively) of 157 star forming galaxies at $0.6\le z<1$. Compared to $z\sim 0$, 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 ${\mathrm{M}}_{\mathrm{dyn},\ast }$ we use Jeans Anisotropic Multi-Gaussian Expansion models. For ${\mathrm{M}}_{\mathrm{dyn},\mathrm{eml}}$ 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, ${\mathrm{M}}_{\mathrm{dyn},\mathrm{eml}}$ is on average lower than ${\mathrm{M}}_{\mathrm{dyn},\ast }$, with a mean offset of $-0.15\pm 0.016$ 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.

19 pages, 7 figures, accepted for publication by ApJ, in press

References in corpus (16)

• The Cosmic Evolution Survey (COSMOS) -- Overview
• Improving the full spectrum fitting method: accurate convolution with Gauss-Hermite functions
• Formation of Massive Galaxies at High Redshift: Cold Streams, Clumpy Disks and Compact Spheroids
• UltraVISTA: a new ultra-deep near-infrared survey in COSMOS
• The KMOS^3D Survey: design, first results, and the evolution of galaxy kinematics from 0.7<z<2.7
• Measuring the inclination and mass-to-light ratio of axisymmetric galaxies via anisotropic Jeans models of stellar kinematics
• The MOSFIRE Deep Evolution Field (MOSDEF) Survey: Rest-Frame Optical Spectroscopy for ~1500 H-Selected Galaxies at 1.37 < z < 3.8
• The VIMOS Ultra-Deep Survey: ~10,000 galaxies with spectroscopic redshifts to study galaxy assembly at early epochs 2<z<~6
• The Star Formation Main Sequence in the Hubble Space Telescope Frontier Fields
• A Survey of Galaxy Kinematics to z ~ 1 in the TKRS/GOODS-N Field. I. Rotation and Dispersion Properties
• The Tully-Fisher Relation and Its Residuals for a Broadly Selected Sample of Galaxies
• The KMOS^3D Survey: data release and final survey paper
• The KMOS Redshift One Spectroscopic Survey (KROSS): the origin of disk turbulence in z~0.9 star-forming galaxies
• The KMOS Redshift One Spectroscopic Survey (KROSS): rotational velocities and angular momentum of z~0.9 galaxies
• The volumetric star formation law in the Milky Way
• The SAMI Galaxy Survey: Bayesian Inference for Gas Disk Kinematics using a Hierarchical Gaussian Mixture Model

Cited by in corpus (1)

• The SAMI Survey: Evidence for dynamical coupling of ionised gas and young stellar populations