Recent star formation in high-redshift early-type galaxies: insights from the rest-frame UV

TL;DR

This study uses deep multi-band photometry and HST imaging to analyze the recent star formation activity in high-redshift early-type galaxies, revealing that these galaxies continue forming stars over cosmic time, especially at lower luminosities.

Contribution

It provides new insights into the star formation history of early-type galaxies at high redshift using UV data combined with morphological analysis.

Findings

Early-type galaxies form stars over the entire age of the universe.

Most star formation in luminous early-types occurs before z=1.

Less luminous early-types form a larger fraction of their mass after z=1.

Abstract

We combine deep UBVRIzJK photometry from the MUSYC survey with redshifts from the COMBO-17 survey to study the rest-frame ultraviolet (UV) properties of 674 high-redshift (0.5<z<1) early-type galaxies, drawn from the Extended Chandra Deep Field South (E-CDFS). Galaxy morphologies are determined through visual inspection of Hubble Space Telescope (HST) images taken from the GEMS survey. We harness the sensitivity of the UV to young (<1 Gyrs old) stars to quantify the recent star formation history of the early-type population. We find compelling evidence that early-types of all luminosities form stars over the lifetime of the Universe, although the bulk of their star formation is already complete at high redshift. Luminous (-23<M(V)<-20.5) early-types form 10-15 percent of their mass after z=1, while their less luminous (M(V)>-20.5) counterparts form 30-60 percent of their mass in the same redshift range.