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Abstract

The VLT LEGA-C Survey has collected high-quality spectra of 3000 galaxies at redshifts z = 0.6-1, with the aim of revealing the internal dynamics and stellar population content of these early-type galaxies. We have reconstructed the star formation histories (SFHs) of these galaxies, using a custom full spectrum fitting algorithm, which offers a direct connection between galaxies' descendants and their progenitors at higher redshifts by tracing their individual evolution through time. Due to S/N constraints, reconstructing SFHs was previously only possible for local galaxies, however, the stellar populations of present-day massive galaxies are too old to resolve their stellar age distribution. We find that at z 1 the age of a galaxy correlates strongly with stellar velocity dispersion and ongoing star-formation (SF) activity, with the stellar content in higher velocity dispersion, passive galaxies having formed earlier and faster. The SFHs of quiescent galaxies are generally consistent with passive evolution since their main SF epoch, but 16% show clear evidence of a rejuvenation event in their recent past. The mean age of stars in galaxies that are star-forming is generally significantly younger, with SF peaking after z < 1.5 for almost all star-forming galaxies in the sample: many of these still have either constant or rising SFRs on timescales > 100 Myrs. By combining the lookback approach with the archaeological approach, these results illustrate the potential offered by high-S/N spectroscopy of high- redshift galaxies.