Abstract
The dramatic first images with JWST demonstrated its power to provide unprecedented spatial detail for galaxies in the high-redshift universe. Here, we leverage the resolution and depth of ...the JWST Cosmic Evolution Early Release Science Survey data in the Extended Groth Strip to perform pixel-level morphological classifications of galaxies in JWST F150W imaging using the Morpheus deep-learning framework for astronomical image analysis. By cross-referencing with existing photometric redshift catalogs from the Hubble Space Telescope (HST) CANDELS survey, we show that JWST images indicate the emergence of disk morphologies before
z
∼ 2 and with candidates appearing as early as
z
∼ 5. By modeling the light profile of each object and accounting for the JWST point-spread function, we find the high-redshift disk candidates have exponential surface brightness profiles with an average Sérsic index 〈
n
〉 = 1.04 and >90% displaying “disky” profiles (
n
< 2). Comparing with prior Morpheus classifications in CANDELS we find that a plurality of JWST disk galaxy candidates were previously classified as
compact
based on the shallower HST imagery, indicating that the improved optical quality and depth of the JWST helps to reveal disk morphologies that were hiding in the noise. We discuss the implications of these early disk candidates on theories for cosmological disk galaxy formation.
ABSTRACT
We report optical integral-field spectroscopy in the field of one of the most luminous quasars in the z < 1 Universe, PKS 0454−22, with the Multi-Unit Spectroscopic Explorer. These data ...enable the discovery of three large ionized nebulae emitting in O ii, H β, and O iii with projected areas of 1720, 1520, and 130 pkpc2, which we refer to as N1, N2, and N3, respectively. N1 spatially and kinematically surrounds the quasar host and five nearby galaxies. The morphology and kinematics of N1 are most consistent with stripped interstellar medium resulting from ongoing interactions. Its ionization properties can be explained by quasar photoionization. N2 spatially and kinematically surrounds two galaxies that are at projected distances of d ≈ 90 pkpc and line-of-sight velocities of Δv ≈+1410 km s−1 from the quasar. The morphology and kinematics of N2 are also consistent with stripped interstellar medium. However, its ionization state requires additional ionization sources beyond the quasar, likely from fast shocks as it moves through the hot halo associated with a galaxy overdensity around the quasar. N3 is not coincident with any galaxies with secure redshifts, and may arise from a cool gas structure in the intragroup medium or a dwarf galaxy. These large ionized nebulae demonstrate that interactions can produce cool gas structures on halo scales, while also possibly facilitating quasar fueling. The growing availability of wide-area integral field spectroscopic data will continue to reveal the morphologies, kinematics, and conditions of the gas flows, which may fuel galaxy and black hole growth.
Abstract By combining the James Webb Space Telescope (JWST)/NIRCam JADES and CEERS extragalactic data sets, we have uncovered a sample of 21 T and Y brown dwarf candidates at best-fit distances ...between 0.1 and 4.2 kpc. These sources were selected by targeting the blue 1–2.5 μ m colors and red 3–4.5 μ m colors that arise from molecular absorption in the atmospheres of T eff < 1300 K brown dwarfs. We fit these sources using multiple models of substellar atmospheres and present the resulting fluxes, sizes, effective temperatures, and other derived properties for the sample. If confirmed, these fits place the majority of the sources in the Milky Way thick disk and halo. We observe proper motions for seven of the candidate brown dwarfs, with directions in agreement with the plane of our Galaxy, providing evidence that they are not extragalactic in nature. We demonstrate how the colors of these sources differ from selected high-redshift galaxies, and explore the selection of these sources in planned large-area JWST NIRCam surveys. Deep imaging with JWST/NIRCam presents an an excellent opportunity for finding and understanding these ultracool dwarfs at kiloparsec distances.
Abstract
We present JWST NIRCam nine-band near-infrared imaging of the luminous
z
= 10.6 galaxy GN-z11 from the JWST Advanced Deep Extragalactic Survey of the GOODS-N field. We find a spectral energy ...distribution (SED) entirely consistent with the expected form of a high-redshift galaxy: a clear blue continuum from 1.5 to 4
μ
m with a complete dropout in F115W. The core of GN-z11 is extremely compact in JWST imaging. We analyze the image with a two-component model, using a point source and a Sérsic profile that fits to a half-light radius of 200 pc and an index
n
= 0.9. We find a low-surface-brightness haze about 0.″4 to the northeast of the galaxy, which is most likely a foreground object but might be a more extended component of GN-z11. At a spectroscopic redshift of 10.60 (Bunker et al. 2023), the comparison of the NIRCam F410M and F444W images spans the Balmer jump. From population-synthesis modeling, here assuming no light from an active galactic nucleus, we reproduce the SED of GN-z11, finding a stellar mass of ∼10
9
M
⊙
, a star formation rate of ∼20
M
⊙
yr
−1
, and a young stellar age of ∼20 Myr. Since massive galaxies at high redshift are likely to be highly clustered, we search for faint neighbors of GN-z11, finding nine galaxies out to ∼5 comoving Mpc transverse with photometric redshifts consistent with
z
= 10.6, and a tenth more tentative dropout only 3″ away. This is consistent with GN-z11 being hosted by a massive dark-matter halo (≈8 × 10
10
M
⊙
), though lower halo masses cannot be ruled out.
We present emission-line ratios from a sample of 27 Lyman-break galaxies from
z
∼ 5.5 − 9.5 with −17.0 <
M
1500
< −20.4, measured from ultra-deep JWST/NIRSpec multi-object spectroscopy from the ...JWST Advanced Deep Extragalactic Survey (JADES). We used a combination of 28 h deep PRISM/CLEAR and 7 h deep
G
395
M
/
F
290
LP
observations to measure, or place strong constraints on, ratios of widely studied rest-frame optical emission lines including H
α
, H
β
, O
II
λλ
3726, 3729, Ne
III
λ
3869, O
III
λ
4959, O
III
λ
5007, O
I
λ
6300, N
II
λ
6583, and S
II
λλ
6716, 6731 in individual
z
> 5.5 spectra. We find that the emission-line ratios exhibited by these
z
∼ 5.5 − 9.5 galaxies occupy clearly distinct regions of line-ratio space compared to typical
z
∼ 0 − 3 galaxies, instead being more consistent with extreme populations of lower-redshift galaxies. This is best illustrated by the O
III
/O
II
ratio, tracing interstellar medium (ISM) ionisation, in which we observe more than half of our sample to have O
III
/O
II
> 10. Our high signal-to-noise spectra reveal more than an order of magnitude of scatter in line ratios such as O
II
/H
β
and O
III
/O
II
, indicating significant diversity in the ISM conditions within the sample. We find no convincing detections of N
II
λ
6583 in our sample, either in individual galaxies, or a stack of all
G
395
M
/
F
290
LP
spectra. The emission-line ratios observed in our sample are generally consistent with galaxies with extremely high ionisation parameters (log
U
∼ −1.5), and a range of metallicities spanning from ∼0.1 ×
Z
⊙
to higher than ∼0.3 ×
Z
⊙
, suggesting we are probing low-metallicity systems undergoing periods of rapid star formation, driving strong radiation fields. These results highlight the value of deep observations in constraining the properties of individual galaxies, and hence probing diversity within galaxy population.
Abstract
We present JWST Extragalactic Medium-band Survey, the first public medium-band imaging survey carried out using JWST/NIRCam and NIRISS. These observations use ∼2 and ∼4
μ
m medium-band ...filters (NIRCam F182M, F210M, F430M, F460M, F480M; and NIRISS F430M and F480M in parallel) over 15.6 arcmin
2
in the Hubble Ultra Deep Field (UDF), thereby building on the deepest multiwavelength public data sets available anywhere on the sky. We describe our science goals, survey design, NIRCam and NIRISS image reduction methods, and describe our first data release of the science-ready mosaics, which reach 5
σ
point-source limits (AB mag) of ∼29.3–29.4 in 2
μ
m filters and ∼28.2–28.7 at 4
μ
m. Our chosen filters create a JWST imaging survey in the UDF that enables novel analysis of a range of spectral features potentially across the redshift range of 0.3 <
z
< 20, including Paschen-
α
, H
α
+N
ii
, and O
iii
+H
β
emission at high spatial resolution. We find that our JWST medium-band imaging efficiently identifies strong line emitters (medium-band colors >1 mag) across redshifts 1.5 <
z
< 9.3, most prominently H
α
+N
ii
and O
iii
+H
β
. We present our first data release including science-ready mosaics of each medium-band image available to the community, adding to the legacy value of past and future surveys in the UDF. This survey demonstrates the power of medium-band imaging with JWST, informing future extragalactic survey strategies using JWST observations.
Abstract
We present a detailed study of the partial rest-optical (
λ
obs
≈ 3600–5600 Å) spectra of
N
= 767 star-forming galaxies at 0.6 <
z
< 1.0 from the Large Early Galaxy Astrophysics Census ...(LEGA-C). We compare this sample with low-redshift (
z
∼ 0) galaxies from the Sloan Digital Sky Survey (SDSS), intermediate-redshift (
z
∼ 1.6) galaxies from the Fiber Multi-Object Spectrograph (FMOS)-COSMOS Survey, and high-redshift (
z
∼ 2) galaxies from the Keck Baryonic Structure Survey (KBSS). At a look-back time of 6–8 Gyr, galaxies with stellar masses
log
(
M
*
/
M
⊙
)
>
10.50
appear remarkably similar to
z
∼ 0 galaxies in terms of their nebular excitation, as measured using O
iii
λ
5008/H
β
. There is some evidence that 0.6 <
z
< 1.0 galaxies with lower
M
*
have higher O
iii
λ
5008/H
β
than
z
∼ 0 galaxies and are more similar to less evolved
z
∼ 1.6 and
z
∼ 2 galaxies, which are offset from the
z
∼ 0 locus at all
M
*
. We explore the impact of selection effects, contributions from active galactic nuclei, and variations in physical conditions (ionization parameter and gas-phase oxygen abundance) on the apparent distribution of O
iii
λ
5008/H
β
and find somewhat higher ionization in 0.6 <
z
< 1.0 galaxies with lower
M
*
relative to
z
∼ 0 galaxies. We use new near-infrared spectroscopic observations of a subsample of LEGA-C galaxies to investigate other probes of enrichment and excitation. Our analysis demonstrates the importance of obtaining complete rest-optical spectra of galaxies in order to disentangle these effects.
ABSTRACT
We present an interstellar medium and stellar population analysis of three spectroscopically confirmed z > 7 galaxies in the Early Release Observations JWST/NIRCam and JWST/NIRSpec data of ...the SMACS J0723.3−7327 cluster.
We use the Bayesian spectral energy distribution-fitting code prospector with a flexible star formation history (SFH), a variable dust attenuation law, and a self-consistent model of nebular emission (continuum and emission lines). Importantly, we self-consistently fit both the emission line fluxes from JWST/NIRSpec and the broad-band photometry from JWST/NIRCam, taking into account slit-loss effects. We find that these three z=7.6–8.5 galaxies (M⋆ ≈ 108 M⊙) are young with rising SFHs and mass-weighted ages of 3–4 Myr, though we find indications for underlying older stellar populations. The inferred gas-phase metallicities broadly agree with the direct metallicity estimates from the auroral lines. The galaxy with the lowest gas-phase metallicity (Zgas= 0.06 Z⊙) has a steeply rising SFH, is very compact (<0.2 kpc), and has a high star formation rate surface density (ΣSFR ≈ 22 M⊙ yr−1 kpc−2), consistent with rapid gas accretion. The two other objects with higher gas-phase metallicities show more complex multicomponent morphologies on kpc scales, indicating that their recent increase in star formation rate is driven by mergers or internal, gravitational instabilities. We discuss effects of assuming different SFH priors or only fitting the photometric data. Our analysis highlights the strength and importance of combining JWST imaging and spectroscopy for fully assessing the nature of galaxies at the earliest epochs.
Abstract We present a catalog of 717 candidate galaxies at z > 8 selected from 125 square arcmin of NIRCam imaging as part of the JWST Advanced Deep Extragalactic Survey (JADES). We combine the full ...JADES imaging data set with data from the JWST Extragalactic Medium Survey and First Reionization Epoch Spectroscopic COmplete Survey (FRESCO) along with extremely deep existing observations from Hubble Space Telescope (HST)/Advanced Camera for Surveys (ACS) for a final filter set that includes 15 JWST/NIRCam filters and five HST/ACS filters. The high-redshift galaxy candidates were selected from their estimated photometric redshifts calculated using a template-fitting approach, followed by visual inspection from seven independent reviewers. We explore these candidates in detail, highlighting interesting resolved or extended sources, sources with very red long-wavelength slopes, and our highest-redshift candidates, which extend to z phot ∼ 18. Over 93% of the sources are newly identified from our deep JADES imaging, including 31 new galaxy candidates at z phot > 12. We also investigate potential contamination by stellar objects, and do not find strong evidence from spectral energy distribution fitting that these faint high-redshift galaxy candidates are low-mass stars. Using 42 sources in our sample with measured spectroscopic redshifts from NIRSpec and FRESCO, we find excellent agreement to our photometric redshift estimates, with no catastrophic outliers and an average difference of 〈Δ z = z phot − z spec 〉 = 0.26. These sources comprise one of the most robust samples for probing the early buildup of galaxies within the first few hundred million years of the Universe’s history.
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