14 research outputs found
A gravitationally unstable gas disk of a starburst galaxy 12 billion years ago
Submillimeter bright galaxies in the early Universe are vigorously forming
stars at ~1000 times higher rate than the Milky Way. A large fraction of stars
is formed in the central 1 kiloparsec region, that is comparable in size to
massive, quiescent galaxies found at the peak of the cosmic star formation
history, and eventually the core of giant elliptical galaxies in the
present-day Universe. However, the physical and kinematic properties inside a
compact starburst core are poorly understood because dissecting it requires
angular resolution even higher than the Hubble Space Telescope can offer. Here
we report 550 parsec-resolution observations of gas and dust in the brightest
unlensed submillimeter galaxy at z=4.3. We map out for the first time the
spatial and kinematic structure of molecular gas inside the heavily
dust-obscured core. The gas distribution is clumpy while the underlying disk is
rotation-supported. Exploiting the high-quality map of molecular gas mass
surface density, we find a strong evidence that the starburst disk is
gravitationally unstable, implying that the self-gravity of gas overcomes the
differential rotation and the internal pressure by stellar radiation feedback.
The observed molecular gas would be consumed by star formation in a timescale
of 100 million years, that is comparable to those in merging starburst
galaxies. Our results suggest that the most extreme starburst in the early
Universe originates from efficient star formation due to a gravitational
instability in the central 2 kpc region.Comment: Published in Nature on August 30 2018 (submitted version
Are JWST/NIRCam color gradients in the lensed z=2.3 dusty star-forming galaxy El Anzuelo due to central dust attenuation or inside-out galaxy growth?
Gradients in the mass-to-light ratio of distant galaxies impede our ability
to characterize their size and compactness. The long-wavelength filters of
's NIRCam offer a significant step forward. For galaxies at Cosmic Noon
(), this regime corresponds to the rest-frame near-infrared, which is
less biased towards young stars and captures emission from the bulk of a
galaxy's stellar population. We present an initial analysis of an extraordinary
lensed dusty star-forming galaxy (DSFG) at behind the
cluster (), named ("The Fishhook") after its partial
Einstein-ring morphology. The FUV-NIR SED suggests an intrinsic star formation
rate of and dust attenuation , in line with other DSFGs on the star-forming main sequence. We develop a
parametric lens model to reconstruct the source-plane structure of dust imaged
by the Atacama Large Millimeter/submillimeter Array, far-UV to optical light
from , and near-IR imaging with 8 filters of /NIRCam, as part of
the Prime Extragalactic Areas for Reionization and Lensing Science (PEARLS)
program. The source-plane half-light radius is remarkably consistent from m, despite a clear color gradient where the inferred galaxy center is
redder than the outskirts. We interpret this to be the result of both a
radially-decreasing gradient in attenuation and substantial spatial offsets
between UV- and IR-emitting components. A spatial decomposition of the SED
reveals modestly suppressed star formation in the inner kiloparsec, which
suggests that we are witnessing the early stages of inside-out quenching.Comment: 29 pages, 11 figures, 5 tables. Accepted for publication in Ap
Magellanic System Stars Identified in the SMACS J0723.3-7327 JWST ERO Images
We identify 68 distant stars in JWST/NIRCam ERO images of the field of galaxy
cluster SMACS J0723.3-7327 (SMACS 0723). Given the relatively small
() angular separation between SMACS 0723 and the Large
Magellanic Cloud, it is likely that these stars are associated with the LMC
outskirts or Leading Arm. This is further bolstered by a spectral energy
distribution analysis, which suggests an excess of stars at a physical distance
of kpc, consistent with being associated with or located behind the
Magellanic system. In particular, we find that the overall surface density of
stars brighter than 27.0 mag in the field of SMACS 0723 is 2.3 times that
of stars in a blank field with similar galactic latitude (the North Ecliptic
Pole Time Domain Field), and that the density of stars in the SMACS 0723 field
with SED-derived distances consistent with the Magellanic system is 7.3
times larger than that of the blank field. The candidate stars at these
distances are consistent with a stellar population at the same distance modulus
with [Fe/H] and an age of Gyr. On the assumption that all
of the 68 stars are associated with the LMC, then the stellar density of the
LMC at the location of the SMACS 0723 field is stars kpc,
which helps trace the density of stars in the LMC outskirts.Comment: Submitted to ApJ, comments welcom
The JWST Discovery of the Triply-imaged Type Ia "Supernova H0pe" and Observations of the Galaxy Cluster PLCK G165.7+67.0
A Type Ia supernova (SN) at was discovered in James Webb Space
Telescope Near Infrared Camera imaging of the galaxy cluster PLCK G165.7+67.0
(G165; ). The SN is situated 1.5-2kpc from its host galaxy Arc 2 and
appears in three different locations as a result of gravitational lensing by
G165. These data can yield a value for Hubble's constant using time delays from
this multiply-imaged SN Ia that we call "SN H0pe." Over the entire field we
identified 21 image multiplicities, confirmed five of them using Near-Infrared
Spectrograph (NIRspec), and constructed a new lens model that gives a total
mass within 600kpc of ( M. The
photometry uncovered a galaxy overdensity at Arc 2's redshift. NIRSpec
confirmed six member galaxies, four of which surround Arc 2 with relative
velocity 900 km s and projected physical extent 33
kpc. Arc 2 dominates the stellar mass (
M), which is a factor of ten higher than other members of this
compact galaxy group. These other group members have specific star formation
rates (sSFR) of 2-260Gyr derived from the H-line flux corrected
for stellar absorption, dust extinction, and slit losses. Another group
centered on the dusty star forming galaxy Arc 1 is at . The total SFR
for the Arc 1 group ( M yr) translates to a supernova
rate of 1 SNe yr, suggesting that regular monitoring of this
cluster may yield additional SNe.Comment: 27 pages, submitted to Ap
Hidden giants in JWST's PEARLS: An ultra-massive z=4.26 sub-millimeter galaxy that is invisible to HST
We present a multi-wavelength analysis using SMA, JCMT, NOEMA, JWST, HST, and
SST of two dusty strongly star-forming galaxies, 850.1 and 850.2, seen through
the massive cluster lens A1489. These SMA-located sources both lie at z=4.26
and have bright dust continuum emission, but 850.2 is a UV-detected Lyman-break
galaxy, while 850.1 is undetected at <2um, even with deep JWST/NIRCam
observations. We investigate their stellar, ISM, and dynamical properties,
including a pixel-level SED analysis to derive sub-kpc-resolution stellar-mass
and Av maps. We find that 850.1 is one of the most massive and highly obscured,
Av~5, galaxies known at z>4 with M*~10^11.8 Mo (likely forming at z>6), and
850.2 is one of the least massive and least obscured, Av~1, members of the z>4
dusty star-forming population. The diversity of these two dust-mass-selected
galaxies illustrates the incompleteness of galaxy surveys at z>3-4 based on
imaging at <2um, the longest wavelengths feasible from HST or the ground. The
resolved mass map of 850.1 shows a compact stellar mass distribution,
Re(mass)~1kpc, but its expected evolution to z~1.5 and then z~0 matches both
the properties of massive, quiescent galaxies at z~1.5 and ultra-massive
early-type galaxies at z~0. We suggest that 850.1 is the central galaxy of a
group in which 850.2 is a satellite that will likely merge in the near future.
The stellar morphology of 850.1 shows arms and a linear bar feature which we
link to the active dynamical environment it resides within.Comment: Submitted to ApJ, comments welcome
Hidden Giants in JWST's PEARLS: An Ultramassive z = 4.26 Submillimeter Galaxy that Is Invisible to HST
We present a multiwavelength analysis using the Submillimeter Array (SMA), James Clerk Maxwell Telescope, NOEMA, JWST, the Hubble Space Telescope (HST), and the Spitzer Space Telescope of two dusty strongly star-forming galaxies, 850.1 and 850.2, seen through the massive cluster lens A 1489. These SMA-located sources both lie at z = 4.26 and have bright dust continuum emission, but 850.2 is a UV-detected Lyman-break galaxy, while 850.1 is undetected at ≲ 2 μm, even with deep JWST/NIRCam observations. We investigate their stellar, interstellar medium, and dynamical properties, including a pixel-level spectral energy distribution analysis to derive subkiloparsec-resolution stellar-mass and A V maps. We find that 850.1 is one of the most massive and highly obscured, A V ∼ 5, galaxies known at z > 4 with M * ∼1011.8 M ⊙ (likely forming at z > 6), and 850.2 is one of the least massive and least obscured, A V ∼ 1, members of the z > 4 dusty star-forming population. The diversity of these two dust-mass-selected galaxies illustrates the incompleteness of galaxy surveys at z ≳ 3–4 based on imaging at ≲ 2 μm, the longest wavelengths feasible from HST or the ground. The resolved mass map of 850.1 shows a compact stellar-mass distribution, Remass ∼1 kpc, but its expected evolution means that it matches both the properties of massive, quiescent galaxies at z ∼ 1.5 and ultramassive early-type galaxies at z ∼ 0. We suggest that 850.1 is the central galaxy of a group in which 850.2 is a satellite that will likely merge in the near future. The stellar morphology of 850.1 shows arms and a linear bar feature that we link to the active dynamical environment it resides within
Paper 1: The JWST PEARLS View of the El Gordo Galaxy Cluster and of the Structure It Magnifies
The massive galaxy cluster El Gordo (z=0.87) imprints multitudes of
gravitationally lensed arcs onto James Webb Space Telescope (JWST)
Near-Infrared Camera (NIRCam) images. Eight bands of NIRCam imaging were
obtained in the ``Prime Extragalactic Areas for Reionization and Lensing
Science'' (``PEARLS'') program. PSF-matched photometry across Hubble Space
Telescope (HST) and NIRCam filters supplies new photometric redshifts. A new
light-traces-mass lens model based on 56 image multiplicities identifies the
two mass peaks and yields a mass estimate within 500 kpc of ~(7.0 +/- 0.30) x
10^14 Msun. A search for substructure in the 140 cluster members with
spectroscopic redshifts confirms the two main mass components. The southeastern
mass peak that contains the BCG is more tightly bound than the northwestern
one. The virial mass within 1.7 Mpc is (5.1 +/- 0.60) x 10^14 Msun, lower than
the lensing mass. A significant transverse velocity component could mean the
virial mass is underestimated. We contribute one new member to the previously
known z=4.32 galaxy group. Intrinsic (delensed) positions of the five secure
group members span a physical extent of ~60 kpc. Thirteen additional candidates
selected by spectroscopic/photometric constraints are small and faint with a
mean intrinsic luminosity ~2.2 mag fainter than L*. NIRCam imaging admits a
fairly wide range of brightnesses and morphologies for the group members,
suggesting a more diverse galaxy population in this galaxy overdensity.Comment: 24 pages, accepted by Ap
JWST’s PEARLS: A new lens model for ACT-CL J0102−4915, “El Gordo,” and the first red supergiant star at cosmological distances discovered by JWST
The first James Webb Space Telescope (JWST) data on the massive colliding cluster El Gordo allow for 23 known families of multiply lensed images to be confirmed and for eight new members of these families to be identified. Based on these families, which have been confirmed spectroscopically by MUSE, we derived an initial lens model. This model guided the identification of 37 additional families of multiply lensed galaxies, among which 28 are entirely new systems, and nine were previously known. The initial lens model determined geometric redshifts for the 37 new systems. The geometric redshifts agree reasonably well with spectroscopic or photometric redshifts when those are available. The geometric redshifts enable two additional models that include all 60 families of multiply lensed galaxies spanning a redshift range 2 0.8 and has an estimated virial mass close the maximum mass allowed by standard cosmological models. The JWST images also reveal the presence of small-mass perturbers that produce small lensing distortions. The smallest of these is consistent with being a dwarf galaxy at z = 0.87 and has an estimated mass of 3.8 × 109 M⊙, making it the smallest substructure found at z > 0.5. The JWST images also show several candidate caustic-crossing events. One of them is detected at high significance at the expected position of the critical curve and is likely a red supergiant star at z = 2.1878. This would be the first red supergiant found at cosmological distances. The cluster lensing should magnify background objects at z > 6, making more of them visible than in blank fields of a similar size, but there appears to be a deficiency of such objects.J.M.D. acknowledges the support of project PGC2018-101814-B-100 (MCIU/AEI/MINECO/FEDER, UE) Ministerio de Ciencia, Investigación y Universidades. This project was funded by the Agencia Estatal de Investigación, Unidad de Excelencia María de Maeztu, ref. MDM-2017-0765. AZ and AKM acknowledge support by Grant No. 2020750 from the United States-Israel Binational Science Foundation (BSF) and Grant No. 2109066 from the United States National Science Foundation (NSF), and by the Ministry of Science & Technology, Israel. RAW, SHC, and RAJ acknowledge support from NASA JWST Interdisciplinary Scientist grants NAG5-12460, NNX14AN10G and 80NSSC18K0200 from GSFC. EZ acknowledges funding from the Swedish National Space Agency. Work by CJC acknowledges support from the European Research Council (ERC) Advanced Investigator Grant EPOCHS (788113). LD acknowledges the research grant support from the Alfred P. Sloan Foundation (Award Number FG-2021-16495). BLF thanks the Berkeley Center for Theoretical Physics for their hospitality during the writing of this paper. MAM acknowledges the support of a National Research Council of Canada Plaskett Fellowship, and the Australian Research Council Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), through project number CE17010001. CNAW acknowledges funding from the JWST/NIRCam contract NASS-0215 to the University of Arizona. GBC acknowledges the Max Planck Society for financial support through the Max Planck Research Group for S. H. Suyu and the academic support from the German Centre for Cosmological Lensing.Peer reviewe
Possible Ongoing Merger Discovered by Photometry and Spectroscopy in the Field of the Galaxy Cluster PLCK G165.7+67.0
International audienceWe present a detailed study of the Planck-selected binary galaxy cluster PLCK G165.7+67.0 (G165; z = 0.348). A multiband photometric catalog is generated incorporating new imaging from the Large Binocular Telescope/Large Binocular Camera and Spitzer/IRAC to existing imaging. To cope with the different image characteristics, robust methods are applied in the extraction of the matched-aperture photometry. Photometric redshifts are estimated for 143 galaxies in the 4 arcmin2 field of overlap covered by these data. We confirm that strong-lensing effects yield 30 images of 11 background galaxies, of which we contribute new photometric redshift estimates for three image multiplicities. These constraints enable the construction of a revised lens model with a total mass of M 600 kpc = (2.36 ± 0.23) × 1014 M ⊙. In parallel, new spectroscopy using MMT/Binospec and archival data contributes thirteen galaxies that meet our velocity and transverse radius criteria for cluster membership. The two cluster components have a pair-wise velocity of ≲100 km s-1, favoring an orientation in the plane of the sky with a transverse velocity of 100-1700 km s-1. At the same time, the brightest cluster galaxy (BCG) is offset in velocity from the systemic mean value, suggesting dynamical disturbance. New LOFAR and Very Large Array data uncover head-tail radio galaxies in the BCG and a large red galaxy in the northeast component. From the orientation and alignment of the four radio trails, we infer that the two cluster components have already traversed each other, and are now exiting the cluster
Magellanic System Stars Identified in SMACS J0723.3-7327 James Webb Space Telescope Early Release Observations Images
We identify 71 distant stars in James Webb Space Telescope/NIRCam early release observations (ERO) images of the field of galaxy cluster SMACS J0723.3-7327 (SMACS 0723). Given the relatively small (∼10°) angular separation between SMACS 0723 and the Large Magellanic Cloud (LMC), it is likely that these stars are associated with the LMC outskirts or the Leading Arm. This is further bolstered by a spectral energy distribution (SED) analysis, which suggests an excess of stars at a physical distance of 40–100 kpc, consistent with being associated with or located behind the Magellanic system. In particular, we find that the overall surface density of stars brighter than 27.0 mag in the field of SMACS 0723 is ∼2.3 times that of stars in a blank field with similar Galactic latitude (the North Ecliptic Pole Time Domain Field), and that the density of stars in the SMACS 0723 field with SED-derived distances consistent with the Magellanic system is ∼6.1 times larger than that of the blank field. The candidate stars at these distances are consistent with a stellar population at the same distance modulus with [Fe/H] = −1.0 and an age of ∼5.0 Gyr. On the assumption that all of the 71 stars are associated with the LMC, then the stellar density of the LMC at the location of the SMACS 0723 field is ∼740 stars kpc ^−3 , which helps trace the density of stars in the LMC outskirts