844 research outputs found
Hubble Frontier Field Photometric Catalogues of Abell 370 and RXC J2248.7-4431: Multiwavelength photometry, photometric redshifts, and stellar properties
This paper presents multiwavelength photometric catalogues of the last two
Hubble Frontier Fields (HFF), the massive galaxy clusters Abell 370 and RXC
J2248.7-4431. The photometry ranges from imaging performed on the Hubble Space
Telescope (HST) to ground based Very Large Telescope (VLT) and Spitzer/IRAC, in
collaboration with the ASTRODEEP team, and using the ASTRODEEP pipeline. While
the main purpose of this paper is to release the catalogues, we also perform,
as a proof of concept, a brief analysis of z > 6 objects selected using
drop-out method, as well as spectroscopically confirmed sources and multiple
images in both clusters. While dropout methods yield a sample of high-z
galaxies, the addition of longer wavelength data reveals that as expected the
samples have substantial contamination at the ~30-45% level by dusty galaxies
at lower redshifts. Furthermore, we show that spectroscopic redshifts are still
required to unambiguously determine redshifts of multiply imaged systems.
Finally, the now publicly available ASTRODEEP catalogues were combined for all
HFFs and used to explore stellar properties of a large sample of 20,000
galaxies across a large photometric redshift range. The powerful magnification
provided by the HFF clusters allows us an exploration of the properties of
galaxies with intrinsic stellar masses as low as
and intrinsic star formation rates \mbox{SFRs}\sim 0.1\mbox{-}1M_\odot/\mbox
yr at z > 6.Comment: Replaced to match the accepted versio
The first large catalogue of spectroscopic redshifts in Webb's First Deep Field, SMACS J0723.37327
We present a spectroscopic redshift catalogue of the SMACS J0723.37327
field ("Webb's First Deep Field") obtained from JWST/NIRISS grism spectroscopy
and supplemented with JWST/NIRSpec and VLT/MUSE redshifts. The catalogue
contains a total of 190 sources with secure spectroscopic redshifts, including
156 NIRISS grism redshifts, 123 of which are for sources whose redshifts were
previously unknown. These new grism redshifts are secured with two or more
spectroscopic features (64 sources), or with a single spectral feature whose
identity is secured from the object's nine-band photometric redshift (59
sources). These are complemented with 17 NIRSpec and 48 MUSE redshifts,
including six new NIRSpec redshifts identified in this work. In addition to the
cluster galaxy redshifts (for which we provide 40 new
NIRISS absorption-line redshifts), we also find three prominent galaxy
overdensities at higher redshifts - at , , and - that
were until now not seen in the JWST/NIRSpec and VLT/MUSE data. The paper
describes the characteristics of our spectroscopic redshift sample and the
methodology we have employed to obtain it. Our redshift catalogue is made
available to the community at https://niriss.github.io/smacs0723.Comment: 19 pages, 13 figures, 3 appendices. Accepted for publication in MNRA
Extreme damped Lyman- absorption in young star-forming galaxies at
The onset of galaxy formation is thought to be initiated by the infall of
neutral, pristine gas onto the first protogalactic halos. However, direct
constraints on the abundance of neutral atomic hydrogen (HI) in galaxies have
been difficult to obtain at early cosmic times. Here we present spectroscopic
observations with JWST of three galaxies at redshifts , about
Myr after the Big Bang, that show strong damped Lyman-
absorption ( cm) from HI in their local
surroundings, an order of magnitude in excess of the Lyman- absorption
caused by the neutral intergalactic medium at these redshifts. Consequently,
these early galaxies cannot be contributing significantly to reionization, at
least at their current evolutionary stages. Simulations of galaxy formation
show that such massive gas reservoirs surrounding young galaxies so early in
the history of the universe is a signature of galaxy formation in progress.Comment: Submitte
The production of ionizing photons in UV-faint z~3-7 galaxies
The demographics of the production and escape of ionizing photons from
UV-faint early galaxies is a key unknown in discovering the primary drivers of
reionization. With the advent of JWST it is finally possible to observe the
rest-frame optical nebular emission from individual sub-L z>3 galaxies to
measure the production of ionizing photons, . Here we study a
sample of 380 z~3-7 galaxies spanning -23 <M < -15.5 (median
M -18) with deep multi-band HST and JWST/NIRCam photometry
covering the rest-UV to optical from the GLASS and UNCOVER JWST surveys. Our
sample includes 109 galaxies with Lyman-alpha emission detected in MUSE
spectroscopy. We use H-alpha fluxes inferred from NIRCam photometry to estimate
the production rate of ionizing photons which do not escape these galaxies
. We find median
, with a broad
intrinsic scatter 0.42 dex, implying a broad range of galaxy properties and
ages in our UV-faint sample. Galaxies detected with Lyman-alpha have ~0.1 dex
higher , which is explained by their higher
H-alpha EW distribution, implying younger ages, higher sSFR and thus more O/B
stars. We find significant trends of increasing
with increasing H-alpha EW, decreasing UV
luminosity, and decreasing UV slope, implying the production of ionizing
photons is enhanced in young, low metallicity galaxies. We find no significant
evidence for sources with very high ionizing escape fraction
(>0.5) in our sample, based on their photometric properties,
even amongst the Lyman-alpha selected galaxies. This work demonstrates that
considering the full distribution of across galaxy
properties is important for assessing the primary drivers of reionization.Comment: 10 pages, 7 figures, submitted to A&
A Candidate Galaxy Strongly Lensed into a Spatially Resolved Arc
The most distant galaxies known are at z~10-11, observed 400-500 Myr after
the Big Bang. The few z~10-11 candidates discovered to date have been
exceptionally small- barely resolved, if at all, by the Hubble Space Telescope.
Here we present the discovery of SPT0615-JD, a fortuitous z~10
(z_phot=9.9+/-0.6) galaxy candidate stretched into an arc over ~2.5" by the
effects of strong gravitational lensing. Discovered in the Reionization Lensing
Cluster Survey (RELICS) Hubble Treasury program and companion S-RELICS Spitzer
program, this candidate has a lensed H-band magnitude of 25.7+/-0.1 AB mag.
With a magnification of \mu~4-7 estimated from our lens models, the de-lensed
intrinsic magnitude is 27.6+/-0.3 AB mag, and the half-light radius is r_e<0.8
kpc, both consistent with other z>9 candidates. The inferred stellar mass (log
[M* /M_Sun]=9.7^{+0.7}_{-0.5}) and star formation rate (\log [SFR/M_Sun
yr^{-1}]=1.3^{+0.2}_{-0.3}) indicate that this candidate is a typical
star-forming galaxy on the z>6 SFR-M* relation. We note that three independent
lens models predict two counterimages, at least one of which should be of a
similar magnitude to the arc, but these counterimages are not yet detected.
Counterimages would not be expected if the arc were at lower redshift. However,
the only spectral energy distributions capable of fitting the Hubble and
Spitzer photometry well at lower redshifts require unphysical combinations of
z~2 galaxy properties. The unprecedented lensed size of this z~10 candidate
offers the potential for the James Webb Space Telescope to study the geometric
and kinematic properties of a galaxy observed 500 Myr after the Big Bang.Comment: 7 pages, 4 figures. Submitted to ApJ Letter
JWST reveals a possible galaxy merger in triply-lensed MACS0647JD
MACS0647JD is a triply-lensed galaxy originally discovered with
the Hubble Space Telescope. Here we report new JWST imaging, which clearly
resolves MACS0647JD as having two components that are either merging
galaxies or stellar complexes within a single galaxy. Both are very small, with
stellar masses and radii . The brighter
larger component "A" is intrinsically very blue (), likely due
to very recent star formation and no dust, and is spatially extended with an
effective radius . The smaller component "B" appears redder
(), likely because it is older () with mild dust
extinction (), and a smaller radius . We
identify galaxies with similar colors in a high-redshift simulation, finding
their star formation histories to be out of phase. With an estimated stellar
mass ratio of roughly 2:1 and physical projected separation ,
we may be witnessing a galaxy merger 400 million years after the Big Bang. We
also identify a candidate companion galaxy C away, likely
destined to merge with galaxies A and B. The combined light from galaxies A+B
is magnified by factors of 8, 5, and 2 in three lensed images JD1, 2, and
3 with F356W fluxes , , (AB mag 25.1, 25.6, 26.6).
MACS0647JD is significantly brighter than other galaxies recently discovered
at similar redshifts with JWST. Without magnification, it would have AB mag
27.3 (). With a high confidence level, we obtain a photometric
redshift of based on photometry measured in 6 NIRCam filters
spanning , out to rest-frame. JWST NIRSpec
observations planned for January 2023 will deliver a spectroscopic redshift and
a more detailed study of the physical properties of MACS0647JD.Comment: 27 pages, 14 figures, submitted to Natur
MUSiC : a model-unspecific search for new physics in proton-proton collisions at root s=13TeV
Results of the Model Unspecific Search in CMS (MUSiC), using proton-proton collision data recorded at the LHC at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb(-1), are presented. The MUSiC analysis searches for anomalies that could be signatures of physics beyond the standard model. The analysis is based on the comparison of observed data with the standard model prediction, as determined from simulation, in several hundred final states and multiple kinematic distributions. Events containing at least one electron or muon are classified based on their final state topology, and an automated search algorithm surveys the observed data for deviations from the prediction. The sensitivity of the search is validated using multiple methods. No significant deviations from the predictions have been observed. For a wide range of final state topologies, agreement is found between the data and the standard model simulation. This analysis complements dedicated search analyses by significantly expanding the range of final states covered using a model independent approach with the largest data set to date to probe phase space regions beyond the reach of previous general searches.Peer reviewe
Search for new particles in events with energetic jets and large missing transverse momentum in proton-proton collisions at root s=13 TeV
A search is presented for new particles produced at the LHC in proton-proton collisions at root s = 13 TeV, using events with energetic jets and large missing transverse momentum. The analysis is based on a data sample corresponding to an integrated luminosity of 101 fb(-1), collected in 2017-2018 with the CMS detector. Machine learning techniques are used to define separate categories for events with narrow jets from initial-state radiation and events with large-radius jets consistent with a hadronic decay of a W or Z boson. A statistical combination is made with an earlier search based on a data sample of 36 fb(-1), collected in 2016. No significant excess of events is observed with respect to the standard model background expectation determined from control samples in data. The results are interpreted in terms of limits on the branching fraction of an invisible decay of the Higgs boson, as well as constraints on simplified models of dark matter, on first-generation scalar leptoquarks decaying to quarks and neutrinos, and on models with large extra dimensions. Several of the new limits, specifically for spin-1 dark matter mediators, pseudoscalar mediators, colored mediators, and leptoquarks, are the most restrictive to date.Peer reviewe
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