The VANDELS survey: the star-formation histories of massive quiescent galaxies at 1.0 < z < 1.3
Date Issued
2019
Author(s)
Carnall, A. C.
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McLure, R. J.
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Dunlop, J. S.
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Cullen, F.
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McLeod, D. J.
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Wild, V.
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Johnson, B. D.
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Appleby, S.
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Davé, R.
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Amorin, R.
•
•
•
Cimatti, A.
•
•
•
•
•
•
•
Schreiber, C.
•
Talia, M.
•
Zamorani, G.
Abstract
We present a Bayesian full-spectral-fitting analysis of 75 massive (M_* > 10^{10.3} M_☉ ) 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_* > 10^{11} M_☉ . 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_* ∼ 10^{10.5} M_☉ ) 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.
Volume
490
Issue
1
Start page
417
Issn Identifier
0035-8711
Ads BibCode
2019MNRAS.490..417C
Rights
open.access
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