80 research outputs found
RELICS: Strong Lens Models for Five Galaxy Clusters From the Reionization Lensing Cluster Survey
Strong gravitational lensing by galaxy clusters magnifies background
galaxies, enhancing our ability to discover statistically significant samples
of galaxies at z>6, in order to constrain the high-redshift galaxy luminosity
functions. Here, we present the first five lens models out of the Reionization
Lensing Cluster Survey (RELICS) Hubble Treasury Program, based on new HST
WFC3/IR and ACS imaging of the clusters RXC J0142.9+4438, Abell 2537, Abell
2163, RXC J2211.7-0349, and ACT-CLJ0102-49151. The derived lensing
magnification is essential for estimating the intrinsic properties of
high-redshift galaxy candidates, and properly accounting for the survey volume.
We report on new spectroscopic redshifts of multiply imaged lensed galaxies
behind these clusters, which are used as constraints, and detail our strategy
to reduce systematic uncertainties due to lack of spectroscopic information. In
addition, we quantify the uncertainty on the lensing magnification due to
statistical and systematic errors related to the lens modeling process, and
find that in all but one cluster, the magnification is constrained to better
than 20% in at least 80% of the field of view, including statistical and
systematic uncertainties. The five clusters presented in this paper span the
range of masses and redshifts of the clusters in the RELICS program. We find
that they exhibit similar strong lensing efficiencies to the clusters targeted
by the Hubble Frontier Fields within the WFC3/IR field of view. Outputs of the
lens models are made available to the community through the Mikulski Archive
for Space TelescopesComment: Accepted to Ap
A search for transients in the Reionization Lensing Cluster Survey (RELICS): Three new supernovae
The Reionization Cluster Survey (RELICS) imaged 41 galaxy clusters with the
Hubble Space Telescope (HST), in order to detect lensed and high-redshift
galaxies. Each cluster was imaged to about 26.5 AB mag in three optical and
four near-infrared bands, taken in two distinct visits separated by varying
time intervals. We make use of the multiple near-infrared epochs to search for
transient sources in the cluster fields, with the primary motivation of
building statistics for bright caustic crossing events in gravitational arcs.
Over the whole sample, we do not find any significant ()
caustic crossing events, in line with expectations from semi-analytic
calculations but in contrast to what may be naively expected from previous
detections of some bright events, or from deeper transient surveys that do find
high rates of such events. Nevertheless, we find six prominent supernova (SN)
candidates over the 41 fields: three of them were previously reported and three
are new ones reported here for the first time. Out of the six candidates, four
are likely core-collapse (CC) SNe -- three in cluster galaxies, and among which
only one was known before, and one slightly behind the cluster at
. The other two are likely Ia -- both of them previously known,
one probably in a cluster galaxy, and one behind it at . Our study
supplies empirical bounds for the rate of caustic crossing events in galaxy
cluster fields to typical HST magnitudes, and lays the groundwork for a future
SN rate study.Comment: Accepted for publication in MNRAS. 10 pages, 3 figure
Canvass: a crowd-sourced, natural-product screening library for exploring biological space
NCATS thanks Dingyin Tao for assistance with compound characterization. This research was supported by the Intramural Research Program of the National Center for Advancing Translational Sciences, National Institutes of Health (NIH). R.B.A. acknowledges support from NSF (CHE-1665145) and NIH (GM126221). M.K.B. acknowledges support from NIH (5R01GM110131). N.Z.B. thanks support from NIGMS, NIH (R01GM114061). J.K.C. acknowledges support from NSF (CHE-1665331). J.C. acknowledges support from the Fogarty International Center, NIH (TW009872). P.A.C. acknowledges support from the National Cancer Institute (NCI), NIH (R01 CA158275), and the NIH/National Institute of Aging (P01 AG012411). N.K.G. acknowledges support from NSF (CHE-1464898). B.C.G. thanks the support of NSF (RUI: 213569), the Camille and Henry Dreyfus Foundation, and the Arnold and Mabel Beckman Foundation. C.C.H. thanks the start-up funds from the Scripps Institution of Oceanography for support. J.N.J. acknowledges support from NIH (GM 063557, GM 084333). A.D.K. thanks the support from NCI, NIH (P01CA125066). D.G.I.K. acknowledges support from the National Center for Complementary and Integrative Health (1 R01 AT008088) and the Fogarty International Center, NIH (U01 TW00313), and gratefully acknowledges courtesies extended by the Government of Madagascar (Ministere des Eaux et Forets). O.K. thanks NIH (R01GM071779) for financial support. T.J.M. acknowledges support from NIH (GM116952). S.M. acknowledges support from NIH (DA045884-01, DA046487-01, AA026949-01), the Office of the Assistant Secretary of Defense for Health Affairs through the Peer Reviewed Medical Research Program (W81XWH-17-1-0256), and NCI, NIH, through a Cancer Center Support Grant (P30 CA008748). K.N.M. thanks the California Department of Food and Agriculture Pierce's Disease and Glassy Winged Sharpshooter Board for support. B.T.M. thanks Michael Mullowney for his contribution in the isolation, elucidation, and submission of the compounds in this work. P.N. acknowledges support from NIH (R01 GM111476). L.E.O. acknowledges support from NIH (R01-HL25854, R01-GM30859, R0-1-NS-12389). L.E.B., J.K.S., and J.A.P. thank the NIH (R35 GM-118173, R24 GM-111625) for research support. F.R. thanks the American Lebanese Syrian Associated Charities (ALSAC) for financial support. I.S. thanks the University of Oklahoma Startup funds for support. J.T.S. acknowledges support from ACS PRF (53767-ND1) and NSF (CHE-1414298), and thanks Drs. Kellan N. Lamb and Michael J. Di Maso for their synthetic contribution. B.S. acknowledges support from NIH (CA78747, CA106150, GM114353, GM115575). W.S. acknowledges support from NIGMS, NIH (R15GM116032, P30 GM103450), and thanks the University of Arkansas for startup funds and the Arkansas Biosciences Institute (ABI) for seed money. C.R.J.S. acknowledges support from NIH (R01GM121656). D.S.T. thanks the support of NIH (T32 CA062948-Gudas) and PhRMA Foundation to A.L.V., NIH (P41 GM076267) to D.S.T., and CCSG NIH (P30 CA008748) to C.B. Thompson. R.E.T. acknowledges support from NIGMS, NIH (GM129465). R.J.T. thanks the American Cancer Society (RSG-12-253-01-CDD) and NSF (CHE1361173) for support. D.A.V. thanks the Camille and Henry Dreyfus Foundation, the National Science Foundation (CHE-0353662, CHE-1005253, and CHE-1725142), the Beckman Foundation, the Sherman Fairchild Foundation, the John Stauffer Charitable Trust, and the Christian Scholars Foundation for support. J.W. acknowledges support from the American Cancer Society through the Research Scholar Grant (RSG-13-011-01-CDD). W.M.W.acknowledges support from NIGMS, NIH (GM119426), and NSF (CHE1755698). A.Z. acknowledges support from NSF (CHE-1463819). (Intramural Research Program of the National Center for Advancing Translational Sciences, National Institutes of Health (NIH); CHE-1665145 - NSF; CHE-1665331 - NSF; CHE-1464898 - NSF; RUI: 213569 - NSF; CHE-1414298 - NSF; CHE1361173 - NSF; CHE1755698 - NSF; CHE-1463819 - NSF; GM126221 - NIH; 5R01GM110131 - NIH; GM 063557 - NIH; GM 084333 - NIH; R01GM071779 - NIH; GM116952 - NIH; DA045884-01 - NIH; DA046487-01 - NIH; AA026949-01 - NIH; R01 GM111476 - NIH; R01-HL25854 - NIH; R01-GM30859 - NIH; R0-1-NS-12389 - NIH; R35 GM-118173 - NIH; R24 GM-111625 - NIH; CA78747 - NIH; CA106150 - NIH; GM114353 - NIH; GM115575 - NIH; R01GM121656 - NIH; T32 CA062948-Gudas - NIH; P41 GM076267 - NIH; R01GM114061 - NIGMS, NIH; R15GM116032 - NIGMS, NIH; P30 GM103450 - NIGMS, NIH; GM129465 - NIGMS, NIH; GM119426 - NIGMS, NIH; TW009872 - Fogarty International Center, NIH; U01 TW00313 - Fogarty International Center, NIH; R01 CA158275 - National Cancer Institute (NCI), NIH; P01 AG012411 - NIH/National Institute of Aging; Camille and Henry Dreyfus Foundation; Arnold and Mabel Beckman Foundation; Scripps Institution of Oceanography; P01CA125066 - NCI, NIH; 1 R01 AT008088 - National Center for Complementary and Integrative Health; W81XWH-17-1-0256 - Office of the Assistant Secretary of Defense for Health Affairs through the Peer Reviewed Medical Research Program; P30 CA008748 - NCI, NIH, through a Cancer Center Support Grant; California Department of Food and Agriculture Pierce's Disease and Glassy Winged Sharpshooter Board; American Lebanese Syrian Associated Charities (ALSAC); University of Oklahoma Startup funds; 53767-ND1 - ACS PRF; PhRMA Foundation; P30 CA008748 - CCSG NIH; RSG-12-253-01-CDD - American Cancer Society; RSG-13-011-01-CDD - American Cancer Society; CHE-0353662 - National Science Foundation; CHE-1005253 - National Science Foundation; CHE-1725142 - National Science Foundation; Beckman Foundation; Sherman Fairchild Foundation; John Stauffer Charitable Trust; Christian Scholars Foundation)Published versionSupporting documentatio
High-Redshift Galaxy Candidates at as Revealed by JWST Observations of WHL0137-08
JWST was designed to peer into the distant universe and study galaxies nearer
the beginning of time than previously. Here we report the discovery of 12
galaxy candidates observed 300-600 Myr after the Big Bang with photometric
redshifts between z ~ 8.5-13 measured using JWST NIRCam imaging of the galaxy
cluster WHL0137 observed in 8 filters spanning 0.8-5.0 m, plus 9 HST
filters spanning 0.4-1.7 m. Three of these candidates are gravitationally
lensed by the foreground galaxy cluster and have magnifications of . The remaining nine candidates are located in a second JWST NIRCam module,
centered ~29' from the cluster center, with expected magnifications of <~
1.1. Our sample of high-redshift candidates have observed F200W AB magnitudes
between 25.9 and 28.1 mag and intrinsic F200W AB magnitudes between 26.4 and
29.7 mag ( = -22.5 to -17). We find the stellar masses of these
galaxies are in the range = 8 - 9, and down to 7.5 for
the lensed galaxies. All are young with mass-weighted ages < 100 Myr, low dust
content < 0.15 mag, and high specific star formation rates sSFR ~10-50
Gyr for most. One z ~ 9 candidate is consistent with an age < 5 Myr and
a sSFR ~250 Gyr, as inferred from a strong F444W excess, implying
[OIII]+H-beta rest-frame equivalent width ~2000 Angstrom, although an older and
redder z~ 10 object is also allowed. Another z~9 candidate ID9356 is lensed
into an arc 2.6" long by the effects of strong gravitational lensing (~8),
and has at least two bright knots of unevenly distributed star formation. This
arc is the most spatially-resolved galaxy at z~9 known to date, revealing
structures ~30 pc across. Follow-up spectroscopy of WHL0137 with JWST/NIRSpec
is planned for later this year, which will validate some of these candidates
and study their physical properties in more detail.Comment: submitted to Ap
Two lensed star candidates at behind the galaxy cluster MACS J0647.7+7015
We report the discovery of two extremely magnified lensed star candidates
behind the galaxy cluster MACS J0647.7+7015, in recent multi-band James Webb
Space Telescope (JWST) NIRCam observations. The candidates are seen in a
previously known, dropout giant arc that straddles the
critical curve. The candidates lie near the expected critical curve position
but lack clear counter images on the other side of it, suggesting these are
possibly stars undergoing caustic crossings. We present revised lensing models
for the cluster, including multiply imaged galaxies newly identified in the
JWST data, and use them to estimate a background macro-magnification of at
least and at the positions of the two candidates,
respectively. With these values, we expect effective, caustic-crossing
magnifications of for the two star candidates. The Spectral Energy
Distributions (SEDs) of the two candidates match well spectra of B-type stars
with best-fit surface temperatures of K, and K,
respectively, and we show that such stars with masses M
and M, respectively, can become sufficiently magnified to
be observed. We briefly discuss other alternative explanations and conclude
these are likely lensed stars, but also acknowledge that the less magnified
candidate may instead be or reside in a star cluster. These star candidates
constitute the second highest-redshift examples to date after Earendel at
, establishing further the potential of studying extremely
magnified stars to high redshifts with the JWST. Planned visits including
NIRSpec observations will enable a more detailed view of the candidates already
in the near future.Comment: 12 pages, 5 figures, 2 tables. Fixed Fig 3. comments are welcom
RELICS: A Strong Lens Model for SPT-CLJ0615-5746, a z=0.972 Cluster
We present a lens model for the cluster SPT-CLJ06155746, which is the
highest redshift () system in the Reionization of Lensing Clusters
Survey (RELICS), making it the highest redshift cluster for which a full strong
lens model is published. We identify three systems of multiply-imaged lensed
galaxies, two of which we spectroscopically confirm at and ,
which we use as constraints for the model. We find a foreground structure at
, which we include as a second cluster-sized halo in one of our
models; however two different statistical tests find the best-fit model
consists of one cluster-sized halo combined with three individually optimized
galaxy-sized halos, as well as contributions from the cluster galaxies
themselves. We find the total projected mass density within (the
region where the strong lensing constraints exist) to be
~M. If we extrapolate out to
, our projected mass density is consistent with the mass inferred from
weak lensing and from the Sunyaev-Zel'dovich effect
(~M). This cluster is lensing a previously reported
galaxy, which, if spectroscopically confirmed, will be the
highest-redshift strongly lensed galaxy known.Comment: 15 pages, 8 figures 4 tables. ApJ Accepte
Reaching for the stars – JWST/NIRSpec spectroscopy of a lensed star candidate at z = 4.76
We present JWST/NIRSpec observations of a highly magnified star candidate at a photometric redshift of zphot ≃ 4.8, previously detected in JWST/NIRCam imaging of the strong lensing (SL) cluster MACS J0647+7015 (z = 0.591). The spectroscopic observation allows us to precisely measure the redshift of the host arc at zspec = 4.758 ± 0.004, and the star’s spectrum displays clear Lyman- and Balmer-breaks commensurate with this redshift. A fit to the spectrum suggests a B-type super-giant star of surface temperature K with either a redder F-type companion ( K) or significant dust attenuation (AV ≃ 0.82) along the line of sight. We also investigate the possibility that this object is a magnified young globular cluster rather than a single star. We show that the spectrum is in principle consistent with a star cluster, which could also accommodate the lack of flux variability between the two epochs. However, the lack of a counter image and the strong upper limit on the size of the object from lensing symmetry, r ≲ 0.5 pc, could indicate that this scenario is somewhat less likely – albeit not completely ruled out by the current data. The presented spectrum seen at a time when the Universe was only ∼1.2 Gyr old showcases the ability of JWST to study early stars through extreme lensing
Reaching for the stars -- JWST/NIRSpec spectroscopy of a lensed star candidate at
We present JWST/NIRSpec observations of a highly magnified star candidate at
a photometric redshift of , previously detected in
JWST/NIRCam imaging of the strong lensing (SL) cluster MACS J0647+7015
(). The spectroscopic observation allows us to precisely measure the
redshift of the host arc at , and the star's
spectrum displays clear Lyman- and Balmer-breaks commensurate with this
redshift. A fit to the spectrum suggests a B-type super-giant star of surface
temperature K with either a redder F-type
companion (K) or significant dust attenuation
() along the line of sight. We also investigate the possibility
that this object is a magnified young globular cluster rather than a single
star. We show that the spectrum is in principle consistent with a star cluster,
which could also accommodate the lack of flux variability between the two
epochs. However, the lack of a counter image and the strong upper limit on the
size of the object from lensing symmetry, pc, could indicate
that this scenario is somewhat less likely -- albeit not completely ruled out
by the current data. The presented spectrum seen at a time when the Universe
was only Gyr old showcases the ability of JWST to study early stars
through extreme lensing.Comment: Accepted for publication in MNRAS letters. v2 updated to match the
published versio
Analogues of Marine Guanidine Alkaloids Are in Vitro Effective against Trypanosoma cruzi and Selectively Eliminate Leishmania (L.) infantum Intracellular Amastigotes
Synthetic analogues of marine sponge guanidine alkaloids showed in vitro antiparasitic activity against Leishmania (L.) infantum and Trypanosoma cruzi. Guanidines 10 and 11 presented the highest selectivity index when tested against Leishmania. The antiparasitic activity of 10 and 11 was investigated in host cells and in parasites. Both compounds induced depolarization of mitochondrial membrane potential, upregulation of reactive oxygen species levels, and increased plasma membrane permeability in Leishmania parasites. Immunomodulatory assays suggested an NO-independent effect of guanidines 10 and 11 on macrophages. The same compounds also promoted anti-inflammatory activity in L. (L.) infantum-infected macrophages cocultived with splenocytes, reducing the production of cytokines MCP-1 and IFN-γ. Guanidines 10 and 11 affect the bioenergetic metabolism of Leishmania, with selective elimination of parasites via a host-independent mechanism
- …