Abstract
Abstract We present spatially resolved stellar kinematics for 797 z = 0.6–1 galaxies selected from the LEGA-C survey and construct axisymmetric Jeans models to quantify their dynamical mass and degree of rotational support. The survey is K s -band selected, irrespective of color or morphological type, and allows for a first assessment of the stellar dynamical structure of the general L* galaxy population at large look-back time. Using light profiles from Hubble Space Telescope imaging as a tracer, our approach corrects for observational effects (seeing convolution and slit geometry), and uses well-informed priors on inclination, anisotropy, and a non-luminous mass component. Tabulated data include total mass estimates in a series of spherical apertures (1, 5, and 10 kpc; 1 × and 2 × R e), as well as rotational velocities, velocity dispersions, and anisotropy. We show that almost all star-forming galaxies and ∼50% of quiescent galaxies are rotation dominated, with deprojected V/σ ∼ 1–2. Revealing the complexity in galaxy evolution, we find that the most massive star-forming galaxies are among the most rotation dominated, and the most massive quiescent galaxies among the least rotation-dominated galaxies. These measurements set a new benchmark for studying galaxy evolution, using stellar dynamical structure for galaxies at large look-back time. Together with the additional information on stellar population properties from the LEGA-C spectra, the dynamical mass and V/σ measurements presented here create new avenues for studying galaxy evolution at large look-back time.
Highlights
The formation and evolutionary history of galaxies is encoded in the motions of their stars
Axisymmetric galaxies are found to form a larger fraction of the total galaxy population with increasing redshift, which is interpreted as the increased rotational support at high redshift
We present axisymmetric Jeans models for 797 z = 0.6–1 galaxies with spatially resolved stellar kinematic measurements from the Large Early Galaxy Astrophysics Census (LEGA-C) survey
Summary
The formation and evolutionary history of galaxies is encoded in the motions of their stars. There are limitations to the use of ionized gas as a tracer of dynamical structure: while to first-order, the integrated velocity dispersions of ionized gas and stars agree fairly well (Bezanson et al 2018a), there is large scatter for several reasons It reveals only the state of the youngest parts of galaxies. The necessary data to access the stellar dynamical structure–high-signal-to-noise (S/N) continuum spectroscopyis is challenging to obtain and have so far been limited to small samples (van der Marel & van Dokkum 2007; van der Wel & van der Marel 2008; Newman et al 2015, 2018; Guérou et al 2017; Toft et al 2017) that only include very massive, passive galaxies Even when these measurements can be made, the interpretation is complicated by the impact of observing conditions, such as the slit geometry and beam smearing.
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