The vandels survey: The star-formation histories of massive quiescent galaxies at 1.0 < z < 1.3

Abstract

We present a Bayesian full-spectral-fitting analysis of 75 massive (⁠M∗>1010.3M⊙⁠) UVJ-selected galaxies at redshifts of 1.0 < z < 1.3, combining extremely deep rest-frame ultraviolet spectroscopy from VANDELS with multiwavelength photometry. By the use of a sophisticated physical plus systematic uncertainties model, constructed within the BAGPIPES code, we place strong constraints on the star-formation histories (SFHs) of individual objects. We first constrain the stellar mass versus stellar age relationship, finding a steep trend towards earlier average formation time with increasing stellar mass (downsizing) of 1.48+0.34−0.39 Gyr per decade in mass, although this shows signs of flattening at M∗>1011M⊙⁠