SHARDS: Survey for High-z Absorption Red & Dead Sources

TL;DR

SHARDS is an ultra-deep spectro-photometric survey using medium-band filters to identify and analyze high-redshift quiescent galaxies, providing accurate ages, stellar masses, and redshifts, and complementing other astronomical surveys.

Contribution

First unbiased sample of high-z quiescent galaxies using medium-band filters to detect Mg absorption features, enabling precise age, mass, and redshift measurements.

Findings

Unbiased high-z quiescent galaxy sample extending to fainter magnitudes.

Accurate age and stellar mass estimates from spectral features.

Redshift measurements with <2% accuracy.

Abstract

SHARDS, an ESO/GTC Large Program, is an ultra-deep (26.5 mag) spectro-photometric survey with GTC/OSIRIS designed to select and study massive passively evolving galaxies at z=1.0-2.3 in the GOODS-N field using a set of 24 medium-band filters (FWHM~17 nm) covering the 500-950 nm spectral range. Our observing strategy has been planned to detect, for z>1 sources, the prominent Mg absorption feature (at rest-frame ~280 nm), a distinctive, necessary, and sufficient feature of evolved stellar populations (older than 0.5 Gyr). These observations are being used to: (1) derive for the first time an unbiased sample of high-z quiescent galaxies, which extends to fainter magnitudes the samples selected with color techniques and spectroscopic surveys; (2) derive accurate ages and stellar masses based on robust measurements of spectral features such as the Mg(UV) or D(4000) indices; (3) measure their redshift with an accuracy Delta(z)/(1+z)<0.02; and (4) study emission-line galaxies (starbursts and AGN) up to very high redshifts. The well-sampled optical SEDs provided by SHARDS for all sources in the GOODS-N field are a valuable complement for current and future surveys carried out with other telescopes (e.g., Spitzer, HST, and Herschel).