The Large Early Galaxy Astrophysics Census (LEGA-C) Data Release II: dynamical and stellar population properties of z ~< 1 galaxies in the COSMOS field

TL;DR

The LEGA-C Data Release II provides extensive spectroscopic data for ~2000 galaxies at z~0.6-1.0, enabling detailed analysis of their dynamical and stellar properties to advance understanding of galaxy evolution.

Contribution

This work releases a large, high-quality spectroscopic dataset and catalog for intermediate redshift galaxies, including new measurements of velocity dispersions and stellar populations.

Findings

Star-forming galaxies have velocity dispersions ~150 km/s and strong Hdelta absorption.

Passive galaxies exhibit higher velocity dispersions ~200 km/s and weaker Hdelta absorption.

Diverse combinations of colors, absorption, and emission lines highlight galaxy evolution complexity.

Abstract

We present the second data release of the Large Early Galaxy Astrophysics Census (LEGA-C), an ESO 130-night public spectroscopic survey conducted with VIMOS on the Very Large Telescope. We release 1988 spectra with typical continuum S / N ~= 20 /Angstrom of galaxies at 0.6 ~< z ~< 1.0, each observed for ~20 hours and fully reduced with a custom-built pipeline. We also release a catalog with spectroscopic redshifts, emission line fluxes, Lick/IDS indices, and observed stellar and gas velocity dispersions that are spatially integrated quantities including both rotational motions and genuine dispersion. To illustrate the new parameter space in the intermediate redshift regime probed by LEGA-C we explore relationships between dynamical and stellar population properties. The star-forming galaxies typically have observed stellar velocity dispersions of ~150 km/s and strong Hdelta absorption (Hd_A ~ 5 Angstrom), while passive galaxies have higher observed stellar velocity dispersions ~200 km/s and weak Hdelta absortion (Hd_A ~ 0 Angstrom). Strong [O III]5007 / Hbeta ratios tend to occur mostly for galaxies with weak Hd_A or galaxies with higher observed velocity dispersion. Beyond these broad trends, we find a large diversity of possible combinations of rest-frame colors, absorption line strengths and emission line detections, illustrating the utility of spectroscopic measurements to more accurately understand galaxy evolution. By making the spectra and value-added catalogs publicly available we encourage the community to take advantage of this very substantial investment in telescope time provided by ESO.