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

Abstract

The Large Early Galaxy Census (LEGA-C) is a Public Spectroscopic Survey of ∼3200 K-band selected galaxies at redshifts z = 0.6 - 1.0 with stellar masses {M}<SUB>*</SUB>\gt {10}<SUP>10</SUP>\quad {M}<SUB>☉ </SUB>, conducted with VIMOS on ESO’s Very Large Telescope. The survey is embedded in the COSMOS field (R.A. = 10h00; {decl}. = +2 {deg}). The 20 hr long integrations produce high-signal-to-noise ratio 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 lookback time, across galaxies of different types and star formation activity. Observations started in 2014 December 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.