1D Kinematics from Stars and Ionized Gas at z ∼ 0.8 from the LEGA-C Spectroscopic Survey of Massive Galaxies
Journal
Astrophysical Journal Letters
Journal Volume
868
Journal Issue
2
Date Issued
2018
Author(s)
Bezanson R
Van Der Wel A
Straatman C
Pacifici C
Barišić I
Bell E.F
Conroy C
D'Eugenio F
Franx M
Gallazzi A
Van Houdt J
Maseda M.V
Muzzin A
Van De Sande J
Sobral D
Spilker J.
Abstract
We present a comparison of the observed, spatially integrated stellar and ionized gas velocity dispersions of ∼1000 massive (log M∗/M⊙ ≳ 10.3) galaxies in the Large Early Galaxy Astrophysics Census survey at 0.6 ≲ z ≲ 1.0. The high S/N ∼ 20 -1 afforded by 20 hr Very Large Telescope/Visible Multi-Object Spectrograph spectra allows for joint modeling of the stellar continuum and emission lines in all galaxies, spanning the full range of galaxy colors and morphologies. These observed integrated velocity dispersions (denoted as σ g.int and σ ∗.int) are related to the intrinsic velocity dispersions of ionized gas or stars, but also include rotational motions through beam smearing and spectral extraction. We find good average agreement between observed velocity dispersions, with (log (σg.intσ ∗.int). This result does not depend strongly on stellar population, structural properties, or alignment with respect to the slit. However, in all regimes we find significant scatter between and σg.intσ ∗.int, with an overall scatter of 0.13 dex of which 0.05 dex is due to observational uncertainties. For an individual galaxy, the scatter between and translates to an additional uncertainty of ∼0.24 dex on dynamical mass derived from σg.int, on top of measurement errors and uncertainties from Virial constant or size estimates. We measure the z ∼ 0.8 stellar mass Faber-Jackson relation and demonstrate that emission line widths can be used to measure scaling relations. However, these relations will exhibit increased scatter and slopes that are artificially steepened by selecting on subsets of galaxies with progressively brighter emission lines. © 2018. The American Astronomical Society. All rights reserved..
Subjects
galaxies: evolution; galaxies: high-redshift; galaxies: kinematics and dynamics
Type
journal article