102 research outputs found
The connection between stellar mass, age and quenching timescale in massive quiescent galaxies at
We present a spectro-photometric study of a mass-complete sample of quiescent
galaxies at with
drawn from the
VANDELS survey, exploring the relationship between stellar mass, age and
star-formation history. Within our sample of 114 galaxies, we derive a
stellar-mass vs stellar-age relation with a slope of Gyr
per decade in stellar mass. When combined with recent literature results, we
find evidence that the slope of this relation remains consistent over the
redshift interval . The galaxies within the VANDELS quiescent display a
wide range of star-formation histories, with a mean star-formation timescale of
Gyr and a mean quenching timescale of Gyr. We also
find a large scatter in the quenching timescales of the VANDELS quiescent
galaxies, in agreement with previous evidence that galaxies at cease
star formation via multiple mechanisms. We then focus on the oldest galaxies in
our sample, finding that the number density of galaxies that quenched before with stellar masses is . Although
uncertain, this estimate is in good agreement with the latest observational
results at , tentatively suggesting that neither rejuvenation nor merger
events are playing a major role in the evolution of the oldest massive
quiescent galaxies within the redshift interval .Comment: Accepted for publication in MNRAS, 11 pages, 6 figure
A first look at the SMACS0723 JWST ERO: spectroscopic redshifts, stellar masses, and star-formation histories
A combined VANDELS and LEGA-C study: the evolution of quiescent galaxy size, stellar mass, and age from z = 0.6 to z = 1.3
We study the relationships between stellar mass, size and age within the
quiescent population, using two mass-complete spectroscopic samples with
, taken from VANDELS at
, and LEGA-C at . Using robust D4000 values, we
demonstrate that the well-known 'downsizing' signature is already in place by
, with D4000 increasing by across a 1
dex mass interval for both VANDELS and LEGA-C. We then proceed to investigate
the evolution of the quiescent galaxy stellar mass-size relation from
to . We find the median size increases by a factor of
at , and
see tentative evidence for flattening of the relation, finding slopes of
and for VANDELS and LEGA-C
respectively. We finally split our sample into galaxies above and below our
fitted mass-size relations, to investigate how size and D4000 correlate.
For LEGA-C, we see a clear difference, with larger galaxies found to have
smaller D4000 at fixed stellar mass. Due to the faintness and smaller
numbers of the VANDELS sample, we cannot confirm whether a similar relation
exists at . We consider whether differences in stellar age or
metallicity are most likely to drive this size-D4000 relation, finding
that any metallicity differences are unlikely to fully explain the observed
offset, meaning smaller galaxies must be older than their larger counterparts.
We find the observed evolution in size, mass and D4000 across the
Gyr from to can be explained by a simple toy
model in which VANDELS galaxies evolve passively, whilst experiencing a series
of minor mergers.Comment: 14 pages, 9 figures, submitted to MNRA
A combined VANDELS and LEGA-C study: the evolution of quiescent galaxy size, stellar mass, and age from z = 0.6 to z = 1.3
We study the relationships between stellar mass, size, and age within the quiescent population, using two mass-complete spectroscopic samples with log10(M⊙/M⊙) > 10.3, taken from VANDELS at 1.0 < z < 1.3, and LEGA-C at 0.6 < z < 0.8. Using robust Dn4000 values, we demonstrate that the well-known 'downsizing' signature is already in place by z 1.1, with Dn4000 increasing by 0.1 across a 1 dex mass interval for both VANDELS and LEGA-C. We then proceed to investigate the evolution of the quiescent galaxy stellar mass-size relation from z -1.1 to z -0.7. We find the median size increases by a factor of 1.9 ± 0.1 at log10(M⊙/M⊙) = 10.5, and see tentative evidence for flattening of the relation, finding slopes of α = 0.72 ± 0.06 and α =\0.56\pm 0.04 for VANDELS and LEGA-C, respectively. We finally split our sample into galaxies above and below our fitted mass-size relations, to investigate how size and Dn4000 correlate. For LEGA-C, we see a clear difference, with larger galaxies found to have smaller Dn4000 at fixed stellar mass. Due to the faintness and smaller numbers of the VANDELS sample, we cannot confirm whether a similar relation exists at z -1.1. We consider whether differences in stellar age or metallicity are most likely to drive this size-Dn4000 relation, finding that any metallicity differences are unlikely to fully explain the observed offset, meaning smaller galaxies must be older than their larger counterparts. We find the observed evolution in size, mass, and Dn4000 across the -2 Gyr from z ∼1.1 to z ∼0.7 can be explained by a simple toy model in which VANDELS galaxies evolve passively whilst experiencing a series of minor mergers
A first look at JWST CEERS: massive quiescent galaxies from 3 < z < 5
We report a robust sample of 9 massive quiescent galaxies at redshift, , selected using the first data from the JWST CEERS programme. Three of these
galaxies are at , constituting the best evidence to date for
quiescent galaxies significantly before . These extreme galaxies have
stellar masses in the range logM, and formed
the bulk of their mass at , with two objects having star-formation
histories that suggest they had already reached logM
by . We report number densities for our sample, demonstrating that
previous work underestimated the number of quiescent galaxies at by
at least a factor of , due to a lack of ultra-deep imaging data at
m. This result deepens the existing tension between
observations and theoretical models, which already struggle to reproduce
previous estimates of quiescent galaxy number densities. Upcoming
wider-area JWST imaging surveys will provide larger samples of such galaxies,
as well as providing opportunities to search for quiescent galaxies at .
The galaxies we report are excellent potential targets for JWST NIRSpec
spectroscopy, which will be required to understand in detail their physical
properties, providing deeper insights into the processes responsible for
quenching star formation during the first billion years.Comment: 11 pages, 6 figures, submitted to MNRA
The ultraviolet continuum slopes (β) of galaxies at z ≃ 8 − 16 from JWST and ground-based near-infrared imaging
A surprising abundance of massive quiescent galaxies at 3 < z < 5 in the first data from JWST CEERS
The galaxy UV luminosity function at z≃11 from a suite of public JWST ERS, ERO and Cycle-1 programs
Evidence for the emergence of dust-free stellar populations at z > 10
We present an analysis of the UV continuum slopes for a sample of
galaxy candidates at . Focusing primarily on a new
sample of galaxies at selected from arcmin of public JWST imaging data across independent datasets,
we investigate the evolution of in the galaxy population at . In
the redshift range , we find evidence for a relationship between
and , such that galaxies with brighter UV luminosities
display redder UV slopes, with . A comparison with literature studies down to suggests that a
relation has been in place from at least , with a
slope that does not evolve strongly with redshift, but with an evolving
normalisation such that galaxies at higher redshifts become bluer at fixed
. We find a significant trend between and redshift, with
the inverse-variance weighted mean value evolving from at to at . Based on a comparison with stellar population models, we find that at
the average UV continuum slope is consistent with the intrinsic blue
limit of `dust-free' stellar populations .
These results suggest that the moderately dust-reddened galaxy population at was essentially dust free at . The extremely blue galaxies
being uncovered at place important constraints on the dust content of
early galaxies, and imply that the already observed galaxy population is likely
supplying an ionizing photon budget capable of maintaining ionized IGM
fractions of per cent at .Comment: 16 pages, 12 figures, submitted to MNRA
A massive quiescent galaxy at redshift 4.658
A. C. Carnall thanks the Leverhulme Trust for their support via a Leverhulme Early Career Fellowship. R. J. McLure, J. S. Dunlop, D. J. McLeod, V. Wild, R. Begley, C. T. Donnan and M. L. Hamadouche acknowledge the support of the Science and Technology Facilities Council. F. Cullen acknowledges support from a UKRI Frontier Research Guarantee Grant (grant reference EP/X021025/1). A. Cimatti acknowledges support from the grant PRIN MIUR 2017 - 20173ML3WW 001.The extremely rapid assembly of the earliest galaxies during the first billion years of cosmic history is a major challenge for our understanding of galaxy formation physics (1; 2; 3; 4; 5). The advent of JWST has exacerbated this issue by confirming the existence of galaxies in significant numbers as early as the first few hundred million years (6; 7; 8). Perhaps even more surprisingly, in some galaxies, this initial highly efficient star formation rapidly shuts down, or quenches, giving rise to massive quiescent galaxies as little as 1.5 billion years after the Big Bang (9; 10), however, due to their faintness and red colour, it has proven extremely challenging to learn about these extreme quiescent galaxies, or to confirm whether any exist at earlier times. Here we report the spectroscopic confirmation of a massive quiescent galaxy, GS-9209, at redshift, z = 4.658, just 1.25 billion years after the Big Bang, using JWST NIRSpec. From these data we infer a stellar mass of M∗ = 3.8 ± 0.2 × 1010 M⊙, which formed over a ≃ 200 Myr period before this galaxy quenched its star formation activity at z=6.5+0.2−0.5, when the Universe was ≃ 800 million years old. This galaxy is both a likely descendent of the highest-redshift submillimetre galaxies and quasars, and a likely progenitor for the dense, ancient cores of the most massive local galaxies.PostprintPeer reviewe
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