56 research outputs found
Unravelling the Dust Attenuation Scaling Relations and their Evolution
We explore the dependence of dust attenuation, as traced by the Balmer decrement, on galactic properties by using a
large sample of SDSS spectra. We use both Partial Correlation Coefficients
(PCC) and Random Forest (RF) analysis to distinguish those galactic parameters
that directly and primarily drive dust attenuation in galaxies, from parameters
that are only indirectly correlated through secondary dependencies. We find
that, once galactic inclination is controlled for, dust attenuation depends
primarily on stellar mass, followed by metallicity and velocity dispersion.
Once the dependence on these quantities is taken into account, there is no
dependence on star formation rate. While the dependence on stellar mass and
metallicity was expected based on simple analytical equations for the
interstellar medium, the dependence on velocity dispersion was not predicted
and we discuss possible scenarios to explain it. We identify a projection of
this multi-dimensional parameters space which minimises the dispersion in terms
of the Balmer decrement and which encapsulates the primary and secondary
dependences of the Balmer decrement into a single parameter defined as the
reduced mass . We show that the dependence of the Balmer decrement
on this single parameter also holds at high redshift, suggesting that the
processes regulating dust production and distribution do not change
significantly through cosmic epochs at least out to z2.Comment: 14 pages, 9 figures (+ Appendix 6 pages, 7 figures), submitted to
MNRAS, comments welcom
The ionising photon production efficiency at z~6 for a sample of bright Lyman-alpha emitters using JEMS and MUSE
We study the ionising photon production efficiency at the end of the Epoch of
Reionisation () for a sample of 35 bright Lyman-
emitters, this quantity is crucial to infer the ionising photon budget of the
Universe. These objects were selected to have reliable spectroscopic redshifts,
assigned based on the profile of their Lyman- emission line, detected
in the MUSE deep fields. We exploit medium-band observations from the JWST
extragalactic medium band survey (JEMS) to find the flux excess corresponding
to the redshifted \ha\ emission line. We estimate the UV luminosity by fitting
the full JEMS photometry, along with several HST photometric points, with
\texttt{Prospector}. We find a median ultra-violet continuum slope of for the sample, indicating young stellar populations
with little-to-no dust attenuation. Supported by this, we derive
with no dust attenuation and find a median value of
log. If we
perform dust attenuation corrections and assume a Calzetti attenuation law, our
values are lowered by dex. Our results suggest Lyman-
emitters at the Epoch of Reionisation have enhanced compared to
previous estimations from literature, in particular, when compared to the
non-Lyman- emitting population. This initial study provides a promising
outlook on the characterisation of ionising photon production in the early
Universe. In the future, a more extensive study will be performed on the entire
dataset provided by the JWST Advanced Deep Extragalactic Survey (JADES). Thus,
for the first time, allowing us toComment: 11 pages, 5 figures in main paper. 10 pages, 30 figures in appendix.
Submitted to MNRA
JWST reveals a population of ultra-red, flattened disk galaxies at 2<z<6 previously missed by HST
With just a month of data, JWST is already transforming our view of the
Universe, revealing and resolving starlight in unprecedented populations of
galaxies. Although ``HST-dark" galaxies have previously been detected at long
wavelengths, these observations generally suffer from a lack of spatial
resolution which limits our ability to characterize their sizes and
morphologies. Here we report on a first view of starlight from a subset of the
HST-dark population that are bright with JWST/NIRCam (4.4m<24.5mag) and
very faint or even invisible with HST (1.6m). In this Letter we focus
on a dramatic and unanticipated population of physically extended galaxies
(0.17''). These 12 galaxies have photometric redshifts , high
stellar masses , and significant
dust-attenuated star formation. Surprisingly, the galaxies have elongated
projected axis ratios at 4.4m, suggesting that the population is
disk-dominated or prolate. Most of the galaxies appear red at all radii,
suggesting significant dust attenuation throughout. We refer to these red,
disky, HST-dark galaxies as Ultra-red Flattened Objects (UFOs). With
(F444W)~kpc, the galaxies are similar in size to compact massive
galaxies at and the cores of massive galaxies and S0s at . The
stellar masses, sizes, and morphologies of the sample suggest that some could
be progenitors of lenticular or fast-rotating galaxies in the local Universe.
The existence of this population suggests that our previous censuses of the
universe may have missed massive, dusty edge-on disks, in addition to
dust-obscured starbursts
A recently quenched galaxy 700 million years after the Big Bang
Local and low-redshift (z 1010 M⊙) and relatively old. Here we report a (mini-)quenched galaxy at z = 7.3, when the Universe was only 700 Myr old. The JWST/NIRSpec spectrum is very blue (U–V = 0.16 ± 0.03 mag) but exhibits a Balmer break and no nebular emission lines. The galaxy experienced a short starburst followed by rapid quenching; its stellar mass (4–6 × 108 M⊙) falls in a range that is sensitive to various feedback mechanisms, which can result in perhaps only temporary quenching
JADES: Resolving the Stellar Component and Filamentary Overdense Environment of HST-Dark Submillimeter Galaxy HDF850.1 at
HDF850.1 is the brightest submillimeter galaxy (SMG) in the Hubble Deep
Field. It is known as a heavily dust-obscured star-forming galaxy embedded in
an overdense environment at . With nine-band NIRCam images at 0.8-5.0
m obtained through the JWST Advanced Deep Extragalactic Survey (JADES), we
detect and resolve the rest-frame UV-optical counterpart of HDF850.1, which
splits into two components because of heavy dust obscuration in the center. The
southern component leaks UV and H photons, bringing the galaxy
100 times above the empirical relation between infrared excess and UV
continuum slope (IRX-). The northern component is higher in
dust attenuation and thus fainter in UV and H surface brightness. We
construct a spatially resolved dust attenuation map from the NIRCam images,
well matched with the dust continuum emission obtained through millimeter
interferometry. The whole system hosts a stellar mass of
and star-formation rate of
, placing the galaxy at the
massive end of the star-forming main sequence at this epoch. We further confirm
that HDF850.1 resides in a complex overdense environment at ,
which hosts another luminous SMG at (GN10). The filamentary structures
of the overdensity are characterized by 109 H-emitting galaxies
confirmed through NIRCam slitless spectroscopy at 3.9-5 m, of which only
eight were known before the JWST observations. Given the existence of a similar
galaxy overdensity in the GOODS-S field, our results suggest that % of
the cosmic star formation at occur in protocluster environments.Comment: 44 pages, 16 figures, 2 tables. Resubmitted to ApJ after including
the first-round referee's comment
JADES: Resolving the Stellar Component and Filamentary Overdense Environment of Hubble Space Telescope (HST)-dark Submillimeter Galaxy HDF850.1 at z = 5.18
© 2024 The Author(s). Published by the American Astronomical Society. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY), https://creativecommons.org/licenses/by/4.0/HDF850.1 is the brightest submillimeter galaxy (SMG) in the Hubble Deep Field. It is known as a heavily dust-obscured star-forming galaxy embedded in an overdense environment at z = 5.18. With nine-band NIRCam images at 0.8–5.0 μm obtained through the JWST Advanced Deep Extragalactic Survey, we detect and resolve the rest-frame UV–optical counterpart of HDF850.1, which splits into two components because of heavy dust obscuration in the center. The southern component leaks UV and Hα photons, bringing the galaxy ∼100 times above the empirical relation between infrared excess and UV continuum slope (IRX–β UV). The northern component is higher in dust attenuation and thus fainter in UV and Hα surface brightness. We construct a spatially resolved dust-attenuation map from the NIRCam images, well matched with the dust continuum emission obtained through millimeter interferometry. The whole system hosts a stellar mass of 1010.8±0.1 M ⊙ and star formation rate (SFR) of 102.8±0.2 M ⊙ yr−1, placing the galaxy at the massive end of the star-forming main sequence at this epoch. We further confirm that HDF850.1 resides in a complex overdense environment at z = 5.17–5.30, which hosts another luminous SMG at z = 5.30 (GN10). The filamentary structures of the overdensity are characterized by 109 Hα-emitting galaxies confirmed through NIRCam slitless spectroscopy at 3.9–5 μm, of which only eight were known before the JWST observations. Given the existence of a similar galaxy overdensity in the GOODS-S field, our results suggest that 50% ± 20% of the cosmic star formation at z = 5.1–5.5 occur in protocluster environments.Peer reviewe
JWST-JADES. Possible Population III signatures at z=10.6 in the halo of GN-z11
Finding the first generation of stars formed out of pristine gas in the early
Universe, known as Population III (PopIII) stars, is one of the most important
goals of modern astrophysics. Recent models suggest that PopIII stars may form
in pockets of pristine gas in the halo of more evolved galaxies. Here we
present NIRSpec-IFU and NIRSpec-MSA observations of the region around GN-z11,
an exceptionally luminous galaxy at , which reveal a 5
detection of a feature consistent with being HeII1640 emission at the
redshift of GN-z11. The very high equivalent width of the putative HeII
emission in this clump (170 A), and the lack of metal lines, can be explained
in terms of photoionisation by PopIII stars, while photoionisation by PopII
stars is inconsistent with the data. It would also indicate that the putative
PopIII stars likely have a top-heavy initial mass function (IMF), with an upper
cutoff reaching at least 500 M. The PopIII bolometric luminosity
inferred from the HeII line would be , which
(with a top-heavy IMF) would imply a total stellar mass formed in the burst of
. We find that photoionisation by the Active
Galactic Nucleus (AGN) in GN-z11 cannot account for the HeII luminosity
observed in the clump, but can potentially be responsible for additional HeII
emission observed closer to GN-z11. We also consider the possibility of in-situ
photoionisation by an accreting Direct Collapse Black Hole (DCBH) hosted by the
HeII clump; we find that this scenario is less favoured, but it remains a
possible alternative interpretation. We also report the detection of a
Ly halo stemming out of GN-z11 and extending out to 2 kpc, as
well as resolved, funnel-shaped CIII] emission, likely tracing the ionisation
cone of the AGN.Comment: Submitted to A&A, 13 pages, 8 figures; some typos corrected and some
minor additional information added to match submitted versio
The JWST Advanced Deep Extragalactic Survey: Discovery of an Extreme Galaxy Overdensity at z = 5.4 with JWST/NIRCam in GOODS-S
© 2024 The Author(s). Published by the American Astronomical Society. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY), https://creativecommons.org/licenses/by/4.0/We report the discovery of an extreme galaxy overdensity at in the GOODS-S field using JWST/NIRCam imaging from JADES and JEMS alongside JWST/NIRCam wide field slitless spectroscopy from FRESCO. We identified potential members of the overdensity using HST+JWST photometry spanning . These data provide accurate and well-constrained photometric redshifts down to . We subsequently confirmed galaxies at using JWST slitless spectroscopy over through a targeted line search for around the best-fit photometric redshift. We verified that of these galaxies reside in the field while galaxies reside in a density around times that of a random volume. Stellar populations for these galaxies were inferred from the photometry and used to construct the star-forming main sequence, where protocluster members appeared more massive and exhibited earlier star formation (and thus older stellar populations) when compared to their field galaxy counterparts. We estimate the total halo mass of this large-scale structure to be using an empirical stellar mass to halo mass relation, which is likely an underestimate as a result of incompleteness. Our discovery demonstrates the power of JWST at constraining dark matter halo assembly and galaxy formation at very early cosmic times.Peer reviewe
The JWST Advanced Deep Extragalactic Survey: Discovery of an Extreme Galaxy Overdensity at with JWST/NIRCam in GOODS-S
We report the discovery of an extreme galaxy overdensity at in the
GOODS-S field using JWST/NIRCam imaging from JADES and JEMS alongside
JWST/NIRCam wide field slitless spectroscopy from FRESCO. We identified
potential members of the overdensity using HST+JWST photometry spanning
. These data provide accurate and
well-constrained photometric redshifts down to .
We subsequently confirmed galaxies at using JWST
slitless spectroscopy over through a
targeted line search for around the best-fit photometric
redshift. We verified that of these galaxies reside in the field while
galaxies reside in a density around times that of a random
volume. Stellar populations for these galaxies were inferred from the
photometry and used to construct the star-forming main sequence, where
protocluster members appeared more massive and exhibited earlier star formation
(and thus older stellar populations) when compared to their field galaxy
counterparts. We estimate the total halo mass of this large-scale structure to
be using an empirical stellar mass to halo mass relation, which is
likely an underestimate as a result of incompleteness. Our discovery
demonstrates the power of JWST at constraining dark matter halo assembly and
galaxy formation at very early cosmic times.Comment: Resubmitted to ApJ based on reviewer report; main text has 15 pages,
6 figures and 1 table; appendix has 1 page, 2 figure sets, and 2 table
JADES + JEMS: A Detailed Look at the Buildup of Central Stellar Cores and Suppression of Star Formation in Galaxies at Redshifts 3 < z < 4.5
We present a spatially resolved study of stellar populations in 6 galaxies
with stellar masses at using 14-filter
JWST/NIRCam imaging from the JADES and JEMS surveys. The 6 galaxies are
visually selected to have clumpy substructures with distinct colors over
rest-frame \r{A}, including a bright dominant stellar core that is
close to their stellar-light centroids. With 23-filter photometry from HST to
JWST, we measure the stellar-population properties of individual structural
components via SED fitting using Prospector. We find that the central stellar
cores are times more massive than the Toomre mass, indicating they
may not form via in-situ fragmentation. The stellar cores have stellar ages of
Gyr that are similar to the timescale of clump inward migration due
to dynamical friction, suggesting that they likely instead formed through the
coalescence of giant stellar clumps. While they have not yet quenched, the 6
galaxies are below the star-forming main sequence by dex. Within each
galaxy, we find that the specific star formation rate is lower in the central
stellar core, and the stellar-mass surface density of the core is already
similar to quenched galaxies of the same masses and redshifts. Meanwhile, the
stellar ages of the cores are either comparable to or younger than the
extended, smooth parts of the galaxies. Our findings are consistent with model
predictions of the gas-rich compaction scenario for the buildup of galaxies'
central regions at high redshifts. We are likely witnessing the coeval
formation of dense central cores, along with the onset of galaxy-wide quenching
at .Comment: 32 pages, 16 figures, submitted to ApJ. Comments are welcom
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