The VLT LEGA-C Spectroscopic Survey: The Physics of Galaxies at a Lookback Time of 7 Gyr

TL;DR

The LEGA-C spectroscopic survey provides high-quality spectra of 3200 galaxies at redshift 0.6-1.0, enabling detailed analysis of their stellar populations and structures 7 billion years ago.

Contribution

This study introduces the LEGA-C survey, a large, deep spectroscopic dataset that allows unprecedented insights into galaxy evolution at intermediate redshifts.

Findings

High signal-to-noise spectra reveal ages, metallicities, and velocity dispersions.

First analysis shows correlations between galaxy structure and spectral properties.

Data enables mapping of stellar content evolution over 7 billion years.

Abstract

The Large Early Galaxy Census (LEGA-C) is a Public Spectroscopic Survey of $\sim3200$ $K$-band selected galaxies at redshifts $z=0.6-1.0$ with stellar masses M_star > 1e10M_sun, conducted with VIMOS on ESO's Very Large Telescope. The survey is embedded in the COSMOS field ($R.A. = 10h00$; $Dec.=+2\deg$). The 20-hour long integrations produce high-$S/N$ continuum spectra that reveal ages, metallicities and velocity dispersions of the stellar populations. LEGA-C's unique combination of sample size and depth will enable us for the first time to map the stellar content at large look-back time, across galaxies of different types and star-formation activity. Observations started in December 2014 and are planned to be completed by mid 2018, with early data releases of the spectra and value-added products. In this paper we present the science case, the observing strategy, an overview of the data reduction process and data products, and a first look at the relationship between galaxy structure and spectral properties, as it existed 7 Gyr ago.