46 research outputs found
Star formation in the cluster CLG0218.3-0510 at z=1.62 and its large-scale environment: the infrared perspective
The galaxy cluster CLG0218.3-0510 at z=1.62 is one of the most distant galaxy
clusters known, with a rich muti-wavelength data set that confirms a mature
galaxy population already in place. Using very deep, wide area (20x20 Mpc)
imaging by Spitzer/MIPS at 24um, in conjunction with Herschel 5-band imaging
from 100-500um, we investigate the dust-obscured, star-formation properties in
the cluster and its associated large scale environment. Our galaxy sample of
693 galaxies at z=1.62 detected at 24um (10 spectroscopic and 683 photo-z)
includes both cluster galaxies (i.e. within r <1 Mpc projected clustercentric
radius) and field galaxies, defined as the region beyond a radius of 3 Mpc. The
star-formation rates (SFRs) derived from the measured infrared luminosity range
from 18 to 2500 Ms/yr, with a median of 55 Ms/yr, over the entire radial range
(10 Mpc). The cluster brightest FIR galaxy, taken as the centre of the galaxy
system, is vigorously forming stars at a rate of 25670 Ms/yr, and the
total cluster SFR enclosed in a circle of 1 Mpc is 116196 Ms/yr. We
estimate a dust extinction of about 3 magnitudes by comparing the SFRs derived
from [OII] luminosity with the ones computed from the 24um fluxes. We find that
the in-falling region (1-3 Mpc) is special: there is a significant decrement
(3.5x) of passive relative to star-forming galaxies in this region, and the
total SFR of the galaxies located in this region is lower (130 Ms/yr/Mpc2) than
anywhere in the cluster or field, regardless of their stellar mass. In a
complementary approach we compute the local galaxy density, Sigma5, and find no
trend between SFR and Sigma5. However, we measure an excess of star-forming
galaxies in the cluster relative to the field by a factor 1.7, that lends
support to a reversal of the SF-density relation in CLG0218.Comment: accepted for publication in MNRAS. v2: minor correction
Molecular gas content in typical L* galaxies at z ∼ 1.5 − 3
To extend the molecular gas measurements to typical L* star-forming galaxies (SFGs) at z ∼ 1.5 − 3, we have observed CO emission for five strongly-lensed galaxies selected from the Herschel Lensing Survey. The combined sample of our L* SFGs with CO-detected SFGs at z >1 from the literature shows a large spread in star formation efficiency (SFE). We find that this spread in SFE is due to variations of several physical parameters, primarily the specific star formation rate, but also stellar mass and redshift. An increase of the molecular gas fraction (f gas) is observed from z ∼ 0.2 to z ∼ 1.2, followed by a quasi non-evolution toward higher redshifts, as found in earlier studies. We provide the first measure of f gas of z >1 SFGs at the low-stellar mass end between 109.4 < M∗/M⊙ < 109.9, which shows a clear f gas uptur
A massive black hole in a low-metallicity AGN at revealed by JWST/NIRSpec IFS
We present JWST/NIRSpec Integral Field Spectrograph rest-frame optical data
of the compact galaxy GS_3073. Its prominent broad components in
several hydrogen and helium lines (while absent in the forbidden lines), and
the detection of a large equivalent width of He II , EW(He II)
Angstrom, unambiguously identify it as an active galactic nucleus
(AGN). We measure a gas-phase metallicity of , lower than what has been inferred for
both more luminous AGN at similar redshift and lower redshift AGN. We
empirically show that classical emission line ratio diagnostic diagrams cannot
be used to distinguish between the primary ionisation source (AGN or star
formation) for such low-metallicity systems, whereas different diagnostic
diagrams involving He II prove very useful, independent of
metallicity. We measure the central black hole mass to be . While this places GS_3073 at the lower
end of known high-redshift black hole masses, it still appears to be
over-massive compared to its host galaxy properties. We detect an outflow with
projected velocity ~km/s and an ionised gas mass outflow rate of
about yr, suggesting that GS_3073 is able to enrich the
intergalactic medium with metals one billion years after the Big Bang.Comment: 15 pages, 10 figures; comments are welcome. Submitted to A&
SHARDS frontier fields: physical properties of a low-mass Lyα emitter at z = 5.75
We analyze the properties of a multiply-imaged Lyman-alpha (Lya) emitter at
z=5.75 identified through SHARDS Frontier Fields intermediate-band imaging of
the Hubble Frontier Fields (HFF) cluster Abell 370. The source, A370-L57, has
low intrinsic luminosity (M_UV~-16.5), steep UV spectral index
(\beta=-2.4+/-0.1), and extreme rest-frame equivalent width of Lya
(EW(Lya)=420+180-120 \AA). Two different gravitational lens models predict high
magnification (\mu~10--16) for the two detected counter-images, separated by
7", while a predicted third counter-image (\mu~3--4) is undetected. We find
differences of ~50% in magnification between the two lens models, quantifying
our current systematic uncertainties. Integral field spectroscopy of A370-L57
with MUSE shows a narrow (FWHM=204+/-10 km/s) and asymmetric Lya profile with
an integrated luminosity L(Lya)~10^42 erg/s. The morphology in the HST bands
comprises a compact clump (r_e<100 pc) that dominates the Lya and continuum
emission and several fainter clumps at projected distances <1 kpc that coincide
with an extension of the Lya emission in the SHARDS F823W17 and MUSE
observations. The latter could be part of the same galaxy or an interacting
companion. We find no evidence of contribution from AGN to the Lya emission.
Fitting of the spectral energy distribution with stellar population models
favors a very young (t<10 Myr), low mass (M*~10^6.5 Msun), and metal poor
(Z<4x10^-3) stellar population. Its modest star formation rate (SFR~1.0
Msun/yr) implies high specific SFR (sSFR~2.5x10^-7 yr^-1) and SFR density
(Sigma_SFR ~ 7-35 Msun/yr/kpc^2). The properties of A370-L57 make it a good
representative of the population of galaxies responsible for cosmic
reionization.Comment: 14 pages, 8 figures, 4 tables. Accepted for publication in Ap
JADES. The diverse population of infant Black Holes at 4<z<11: merging, tiny, poor, but mighty
We present 12 new AGN at 4<z<7 in the JADES survey (in addition to the
previously identified AGN in GN-z11 at z=10.6) revealed through the detection
of a Broad Line Region as seen in the Balmer emission lines. The depth of
JADES, together with the use of three different spectral resolutions, enables
us to probe a lower mass regime relative to previous studies. In a few cases we
find evidence for two broad components of Halpha which suggests that these
could be candidate merging black holes (BHs). The inferred BH masses range
between 8 x 10^7 Msun down to 4 x 10^5 Msun, interestingly probing the regime
expected for Direct Collapse Black Holes. The inferred AGN bolometric
luminosities (~10^44-10^45 erg/s) imply accretion rates that are < 0.5 times
the Eddington rate in most cases. However, small BH, with M_BH ~ 10^6 Msun,
tend to accrete at Eddington or super-Eddington rates. These BH at z~4-11 are
over-massive relative to their host galaxies stellar masses when compared to
the local M_BH-Mstar relation. However, we find that these early BH tend to be
more consistent with the local relation between M_BH and velocity dispersion,
as well as between M_BH and dynamical mass, suggesting that these are more
fundamental and universal relations. On the BPT excitation-diagnostic diagram
these AGN are located in the region that is that is locally occupied by
star-forming galaxies, implying that they would be missed by the standard
classification techniques if they did not display broad lines. Their location
on the diagram is consistent with what expected for AGN hosted in metal poor
galaxies (Z ~ 0.1-0.2 Zsun). The fraction of broad line AGN with L_AGN > 10^44
erg/s, among galaxies in the redshift range 4<z<6, is about 10%, suggesting
that the contribution of AGN and their hosts to the reionization of the
Universe is > 10%.Comment: Submitted to A&A, 25 pages, 13 figures, 4 table
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: Detecting [OIII] Emitters and Testing Strong Line Calibrations in the High- Universe with Ultra-deep JWST/NIRSpec Spectroscopy up to
© 2024 The Author(s). 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 present ten novel [OIII]λ4363 auroral line detections up to z ∼ 9.5 measured from ultra-deep JWST/NIRSpec MSA spectroscopy from the JWST Advanced Deep Extragalactic Survey (JADES). We leverage the deepest spectroscopic observations taken thus far with NIRSpec to determine electron temperatures and oxygen abundances using the direct Te method. We directly compare these results against a suite of locally calibrated strong-line diagnostics and recent high-z calibrations. We find the calibrations fail to simultaneously match our JADES sample, thus warranting a self-consistent revision of these calibrations for the high-z Universe. We find a weak dependence between R2 and O3O2 with metallicity, thus suggesting these line ratios are inefficient in the high-z Universe as metallicity diagnostics and degeneracy breakers. We find R3 and R23 are still correlated with metallicity, but we find a tentative flattening of these diagnostics, thus suggesting future difficulties when applying these strong line ratios as metallicity indicators in the high-z Universe. We also propose and test an alternative diagnostic based on a different combination of R3 and R2 with a higher dynamic range. We find a reasonably good agreement (median offset of 0.002 dex, median absolute offset of 0.13 dex) with the JWST sample at low metallicity, but future investigations are required on larger samples to probe past the turnover point. At a given metallicity, our sample demonstrates higher ionization and excitation ratios than local galaxies with rest-frame EWs(Hβ) ≈200 − 300 Å. However, we find the median rest-frame EWs(Hβ) of our sample to be ∼2× less than the galaxies used for the local calibrations. This EW discrepancy combined with the high ionization of our galaxies does not offer a clear description of [OIII]λ4363 production in the high-z Universe, thus warranting a much deeper examination into the factors influencing these processes.Peer reviewe
JADES: Insights into the low-mass end of the mass–metallicity–SFR relation at 3 < z < 10 from deep JWST/NIRSpec spectroscopy⋆
© 2024 The Author(s). Published by EDP Sciences. 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 analysed the gas-phase metallicity properties of a sample of low-stellar-mass (log M⋆/M⊙ ≲ 9) galaxies at 3 6, with galaxies significantly less enriched than predicted given their M⋆ and SFR (with a median offset in log(O/H) of ∼0.5 dex, significant at ∼5σ). These observations are consistent with an enhanced stochasticity in the gas accretion and star-formation history of high-redshift systems, prompting us to reconsider the nature of the relationship between M⋆, O/H, and SFR in the early Universe.Peer reviewe
The Cosmos in its Infancy: JADES Galaxy Candidates at z > 8 in GOODS-S and GOODS-N
© 2024. The Author(s). Published by the American Astronomical Society. This is an open access article distributed under the Creative Commons Attribution License, to view a copy of the license, see: https://creativecommons.org/licenses/by/4.0/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 〈Δz = 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.Peer reviewe