The VANDELS survey : the star-formation histories of massive quiescent galaxies at 1.0 < z < 1.3
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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⊙. We show that this is consistent with other spectroscopic studies from 0 < z < 2. This relationship places strong constraints on the AGN-feedback models used in cosmological simulations. We demonstrate that, although the relationships predicted by SIMBA and ILLUSTRISTNG agree well with observations at z = 0.1, they are too shallow at z = 1, predicting an evolution of ≲0.5 Gyr per decade in mass. Secondly, we consider the connections between green-valley, post-starburst, and quiescent galaxies, using our inferred SFH shapes and the distributions of galaxy physical properties on the UVJ diagram. The majority of our lowest-mass galaxies (M∗∼1010.5M⊙) are consistent with formation in recent (z < 2), intense starburst events, with time-scales of ≲500 Myr. A second class of objects experience extended star-formation epochs before rapidly quenching, passing through both green-valley and post-starburst phases. The most massive galaxies in our sample are extreme systems: already old by z = 1, they formed at z ∼ 5 and quenched by z = 3. However, we find evidence for their continued evolution through both AGN and rejuvenated star-formation activity.
Carnall , A C , McLure , R J , Dunlop , J S , Cullen , F , McLeod , D J , Wild , V , Johnson , B D , Appleby , S , Davé , R , Amorin , R , Bolzonella , M , Castellano , M , Cimatti , A , Cucciati , O , Gargiulo , A , Garilli , B , Marchi , F , Pentericci , L , Pozzetti , L , Schreiber , C , Talia , M & Zamorani , G 2019 , ' The VANDELS survey : the star-formation histories of massive quiescent galaxies at 1.0 < z < 1.3 ' , Monthly Notices of the Royal Astronomical Society , vol. 490 , no. 1 , pp. 417-439 . https://doi.org/10.1093/mnras/stz2544
Monthly Notices of the Royal Astronomical Society
Copyright © 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. This work has been made available online in accordance with publisher policies or with permission. Permission for further reuse of this content should be sought from the publisher or the rights holder. This is the final published version of the work, which was originally published at https://doi.org/10.1093/mnras/stz2544
DescriptionFunding: UK Science and Technology Facilities Council (ACC, FC, SA).
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