Abstract
The GLASS-JWST Early Release Science (hereafter GLASS-JWST-ERS) Program will obtain and make publicly available the deepest extragalactic data of the ERS campaign. It is primarily designed ...to address two key science questions, namely, “what sources ionized the universe and when?” and “how do baryons cycle through galaxies?”, while also enabling a broad variety of first look scientific investigations. In primary mode, it will obtain NIRISS and NIRSpec spectroscopy of galaxies lensed by the foreground Hubble Frontier Field cluster, Abell 2744. In parallel, it will use NIRCam to observe two fields that are offset from the cluster center, where lensing magnification is negligible, and which can thus be effectively considered blank fields. In order to prepare the community for access to this unprecedented data, we describe the scientific rationale, the survey design (including target selection and observational setups), and present pre-commissioning estimates of the expected sensitivity. In addition, we describe the planned public releases of high-level data products, for use by the wider astronomical community.
Aims. The aim of this work is twofold: first, to assess whether the population of elliptical galaxies in cluster at z~ 1.3 differs from the population in the field and whether their intrinsic ...structure depends on the environment where they belong; second, to constrain their properties 9 Gyr back in time through the study of their scaling relations. Methods. We compared a sample of 56 cluster elliptical galaxies selected from three clusters at 1.2 <z< 1.4 with elliptical galaxies selected at comparable redshift in the GOODS-South field (~30), in the COSMOS area (~180), and in the CANDELS fields (~220). To single out the environmental effects, we selected cluster and field elliptical galaxies according to their morphology. We compared physical and structural parameters of galaxies in the two environments and we derived the relationships between effective radius, surface brightness, stellar mass, and stellar mass density capital sigma Re within the effective radius and central mass density capital sigma sub(1 kpc), within 1 kpc radius. Results. We find that the structure and the properties of cluster elliptical galaxies do not differ from those in the field: they are characterized by the same structural parameters at fixed mass and they follow the same scaling relations. On the other hand, the population of field elliptical galaxies at z~ 1.3 shows a significant lack of massive (M sub(*)> 2 x 10 super(11)M sub(middot in circle)) and large (R sub(e)> 4-5 kpc) elliptical galaxies with respect to the cluster. Nonetheless, at M sub(*)< 2 x 10 super(11)M sub(middot in circle), the two populations are similar. The size-mass relation of cluster and field ellipticals at z~ 1.3 clearly defines two different regimes, above and below a transition mass m sub(t)Asymptotically = to 2-3 x 10 super(10)M sub(middot in circle): at lower masses the relation is nearly flat (R sub(e)is proportional to Mu sub(*) super(-0.1+ or -0.2)), the mean radius is nearly constant at ~1 kpc and, consequenly, capital sigma ReAsymptotically = to capital sigma sub(1 kpc) while, at larger masses, the relation is R sub(e)is proportional to Mu sub(*) super(0.64+ or -0.09). The transition mass marks the mass at which galaxies reach the maximum stellar mass density. Also the capital sigma sub(1 kpc)-mass relation follows two different regimes, above and below the transition mass ( capital sigma sub(1 kpc)is proportional to Mu sub(*) sub(1.07<mt) super(0.64>mt)) defining a transition mass density capital sigma sub(1 kpc)Asymptotically = to 2-3 x 10 super(3)M sub(middot in circle) pc super(-2). The effective stellar mass density capital sigma Re does not correlate with mass; dense/compact galaxies can be assembled over a wide mass regime, independently of the environment. The central stellar mass density, capital sigma sub(1 kpc), besides being correlated with the mass, is correlated to the age of the stellar population: the higher the central stellar mass density, the higher the mass, the older the age of the stellar population. Conclusions. While we found some evidence of environmental effects on the elliptical galaxies as a population, we did not find differences between the intrinsic properties of cluster and field elliptical galaxies at comparable redshift. The structure and the shaping of elliptical galaxies at z~ 1.3 do not depend on the environment. However, a dense environment seems to be more efficient in assembling high-mass large ellipticals, much rarer in the field at this redshift. The correlation found between the central stellar mass density and the age of the galaxies beside the mass shows the close connection of the central regions to the main phases of mass growth.
Abstract
We present the first rest-frame optical size–luminosity relation of galaxies at
z
> 7, using the NIRCam imaging data obtained by the GLASS James Webb Space Telescope Early Release Science ...(GLASS-JWST-ERS) program, providing the deepest extragalactic data of the ERS campaign. Our sample consists of 19 photometrically selected bright galaxies with
m
F444W
≤ 27.8 at 7 <
z
< 9 and
m
F444W
< 28.2 at
z
∼ 9−15. We measure the size of the galaxies in five bands, from rest-frame optical (∼4800 Å) to the UV (∼1600 Å) based on the Sérsic model, and analyse the size–luminosity relation as a function of wavelength. Remarkably, the data quality of the NIRCam imaging is sufficient to probe the half-light radius
r
e
down to ∼100 pc at
z
> 7. Given the limited sample size and magnitude range, we first fix the slope to that observed for larger samples in rest-frame UV using Hubble Space Telescope samples. The median size
r
0
at the reference luminosity
M
= −21 decreases slightly from rest-frame optical (600 ± 80 pc) to UV (450 ± 130 pc). We then refit the size–luminosity relation allowing the slope to vary. The slope is consistent with
β
∼ 0.2 for all bands except F150W, where we find a marginally steeper slope of
β
= 0.53 ± 0.15. The steep UV slope is mainly driven by the smallest and faintest galaxies. If confirmed by larger samples, it implies that the UV size–luminosity relation breaks toward the faint end, as suggested by lensing studies.
Abstract
We present the first James Webb Space Telescope/NIRCam-led determination of 7 <
z
< 9 galaxy properties based on broadband imaging from 0.8 to 5
μ
m as part of the GLASS-JWST Early Release ...Science program. This is the deepest data set acquired at these wavelengths to date, with an angular resolution ≲0.″14. We robustly identify 13 galaxies with signal-to-noise ratio ≳ 8 in F444W from 8 arcmin
2
of data at
m
AB
≤ 28 from a combination of dropout and photometric redshift selection. From simulated data modeling, we estimate the dropout sample purity to be ≳90%. We find that the number density of these F444W-selected sources is broadly consistent with expectations from the UV luminosity function determined from Hubble Space Telescope data. We characterize galaxy physical properties using a Bayesian spectral energy distribution fitting method, finding a median stellar mass of 10
8.5
M
⊙
and age 140 Myr, indicating they started ionizing their surroundings at redshift
z
> 9.5. Their star formation main sequence is consistent with predictions from simulations. Lastly, we introduce an analytical framework to constrain main-sequence evolution at
z
> 7 based on galaxy ages and basic assumptions, through which we find results consistent with expectations from cosmological simulations. While this work only gives a glimpse of the properties of typical galaxies that are thought to drive the reionization of the universe, it clearly shows the potential of JWST to unveil unprecedented details of galaxy formation in the first billion years.
Abstract
We exploit James Webb Space Telescope (JWST) NIRCam observations from the GLASS-JWST-Early Release Science program to investigate galaxy stellar masses at
z
> 7. We first show that JWST ...observations reduce the uncertainties on the stellar mass by a factor of at least 5–10, when compared with the highest-quality data sets available to date. We then study the UV mass-to-light ratio, finding that galaxies exhibit a a two orders of magnitude range of
M
/
L
UV
values for a given luminosity, indicative of a broad variety of physical conditions and star formation histories. As a consequence, previous estimates of the cosmic stellar-mass density—based on an average correlation between UV luminosity and stellar mass—can be biased by as much as a factor of ∼6. Our first exploration demonstrates that JWST represents a new era in our understanding of stellar masses at
z
> 7 and, therefore, of the growth of galaxies prior to cosmic reionization.
Abstract
Star-forming galaxies can exhibit strong morphological differences between the rest-frame far-UV and optical, reflecting inhomogeneities in star formation and dust attenuation. We exploit ...deep, high-resolution, NIRCAM seven-band observations to take a first look at the morphology of galaxies in the epoch of reionization (
z
> 7), and its variation in the rest-frame wavelength range between Ly
α
and 6000–4000 Å, at
z
= 7–12. We find no dramatic variations in morphology with wavelength—of the kind that would have overturned anything we have learned from the Hubble Space Telescope. No significant trends between morphology and wavelengths are detected using standard quantitative morphology statistics. We detect signatures of mergers/interactions in 4/19 galaxies. Our results are consistent with a scenario in which Lyman-break galaxies—observed when the universe is only 400–800 Myr old—are growing via a combination of rapid, galaxy-scale star formation supplemented by the accretion of star-forming clumps and interactions.
Abstract
We present a rest-frame optical morphological analysis of galaxies observed with the NIRCam imager on the James Webb Space Telescope (JWST) as part of the GLASS-JWST Early Release Science ...program. We select 388 sources at redshifts 0.8 <
z
< 5.4 and use the seven 0.9–5
μ
m NIRCam filters to generate rest-frame
gri
composite color images, and conduct visual morphological classification. Compared to Hubble Space Telescope (HST)–based work we find a higher incidence of disks and bulges than expected at
z
> 1.5, revealed by rest-frame optical imaging. We detect 123 clear disks (58 at
z
> 1.5) of which 76 have bulges. No evolution of bulge fraction with redshift is evident: 61% at
z
< 2 (
N
= 110) versus 60% at
z
≥ 2 (
N
= 13). A stellar mass dependence is evident, with bulges visible in 80% of all disk galaxies with mass >10
9.5
M
⊙
(
N
= 41) but only 52% at
M
< 10
9.5
M
⊙
(
N
= 82). We supplement visual morphologies with nonparametric measurements of Gini and asymmetry coefficients in the rest-frame
i
band. Our sources are more asymmetric than local galaxies, with slightly higher Gini values. When compared to high-
z
rest-frame ultraviolet measurements with HST, JWST shows more regular morphological types such as disks, bulges, and spiral arms at
z
> 1.5, with smoother (i.e., lower Gini) and more symmetrical light distributions.
ABSTRACT
We present the JWST cycle 1 53.8 h medium program FRESCO, short for ‘First Reionization Epoch Spectroscopically Complete Observations’. FRESCO covers 62 arcmin2 in each of the two ...GOODS/CANDELS fields for a total area of 124 arcmin2 exploiting JWST’s powerful new grism spectroscopic capabilities at near-infrared wavelengths. By obtaining ∼2 h deep NIRCam/grism observations with the F444W filter, FRESCO yields unprecedented spectra at R ∼ 1600 covering 3.8–5.0 µm for most galaxies in the NIRCam field of view. This setup enables emission line measurements over most of cosmic history, from strong PAH lines at z ∼ 0.2–0.5, to Pa α and Pa β at z ∼ 1–3, He i and S iii at z ∼ 2.5–4.5, H α and N ii at z ∼ 5–6.5, up to O iii and H β for z ∼ 7–9 galaxies. FRESCO’s grism observations provide total line fluxes for accurately estimating galaxy stellar masses and calibrating slit-loss corrections of NIRSpec/MSA spectra in the same field. Additionally, FRESCO results in a mosaic of F182M, F210M, and F444W imaging in the same fields to a depth of ∼28.2 mag (5σ in 0${_{.}^{\prime\prime}}$32 diameter apertures). Here, we describe the overall survey design and the key science goals that can be addressed with FRESCO. We also highlight several, early science results, including: spectroscopic redshifts of Lyman break galaxies that were identified almost 20 yr ago, the discovery of broad-line active galactic nuclei at z > 4, and resolved Pa α maps of galaxies at z ∼ 1.4. These results demonstrate the enormous power for serendipitous discovery of NIRCam/grism observations.
We study the buildup of the bimodal galaxy population using the NEWFIRM Medium-Band Survey, which provides excellent redshifts and well-sampled spectral energy distributions of 2,000 galaxies with K ...< 22.8 at 0.4 < z < 2.2. We first show that star-forming galaxies and quiescent galaxies can be robustly separated with a two-color criterion over this entire redshift range. We then study the evolution of the number density and mass density of quiescent and star-forming galaxies, extending the results of the COMBO-17, DEEP2, and other surveys to z = 2.2. The mass density of quiescent galaxies with M 3 X 1010 M increases by a factor of ~10 from z ~ 2 to the present day, whereas the mass density in star-forming galaxies is flat or decreases over the same time period. Modest mass growth by a factor of ~2 of individual quiescent galaxies can explain roughly half of the strong density evolution at masses >1011 M , due to the steepness of the exponential tail of the mass function. The rest of the density evolution of massive, quiescent galaxies is likely due to transformation (e.g., quenching) of the massive star-forming population, a conclusion which is consistent with the density evolution we observe for the star-forming galaxies themselves, which is flat or decreasing with cosmic time. Modest mass growth does not explain the evolution of less massive quiescent galaxies (~1010.5 M ), which show a similarly steep increase in their number densities. The less massive quiescent galaxies are therefore continuously formed by transforming galaxies from the star-forming population.
ABSTRACT
We present spectroscopic observations obtained at the Large Binocular Telescope in the field of the cluster XLSSJ0223−0436 at z = 1.22. We confirm 12 spheroids cluster members and determine ...stellar velocity dispersion for 7 of them. We combine these data with those in the literature for clusters RXJ0848+4453 at z = 1.27 (8 galaxies) and XMMJ2235−2557 at z = 1.39 (7 galaxies) to determine the Fundamental Plane (FP) of cluster spheroids. We find that the FP at z ∼ 1.3 is offset and rotated (∼3σ) with respect to the local FP. The offset corresponds to a mean evolution Δlog(Mdyn/LB) = (−0.5 ± 0.1)z. High-redshift galaxies follow a steeper mass-dependent Mdyn/LB–Mdyn relation than local ones. Assuming Δ log(Mdyn/LB) = Δ log(M*/LB), higher mass galaxies log(Mdyn/M⊙) ≥ 11.5 have a higher formation redshift (zf ≥ 6.5) than lower mass ones zf ≤2 for log(Mdyn/M⊙ ≤ 10), with a median zf ≃ 2.5 for the whole sample. Also, galaxies with higher stellar mass density host stellar populations formed earlier than those in lower density galaxies. At fixed initial mass function, Mdyn/M* varies systematically with mass and mass density. It follows that the evolution of the stellar populations (M*/LB) accounts for the observed evolution of Mdyn/LB for Mdyn > 1011 M⊙ galaxies, while accounts for ∼85 per cent of the evolution at Mdyn < 1011 M⊙. We find no evidence in favour of structural evolution of individual galaxies, while we find evidences that spheroids later added to the population may account for the observed discrepancy between Δlog(Mdyn/LB) and Δ log(M*/LB) at masses <1011 M⊙. Thus, the evolution of the FP of cluster spheroids is consistent with the mass-dependent and mass density-dependent evolution of their stellar populations superimposed to a minor contribution of spheroids joining the population at later times.
PDF
