Search

We investigate the Lyman-$\alpha$ (Ly$\alpha$) and Lyman continuum (LyC) properties of the Sunburst Arc, a $z=2.37$ gravitationally lensed galaxy with a multiply-imaged, compact region leaking LyC and a triple-peaked Ly$\alpha$ profile indicating direct Ly$\alpha$ escape. Non-LyC-leaking regions show a redshifted Ly$\alpha$ peak, a redshifted and central Ly$\alpha$ peak, or a triple-peaked Ly$\alpha$ profile. We measure the properties of the Ly$\alpha$ profile from different regions of the galaxy using $R\sim5000$ Magellan/MagE spectra. We compare the Ly$\alpha$ spectral properties to LyC and narrowband Ly$\alpha$ maps from Hubble Space Telescope (HST) imaging to explore the subgalactic Ly$\alpha-$LyC connection. We find strong correlations (Pearson correlation coefficient $r>0.6$) between the LyC escape fraction ($f_{\rm esc}^{\rm LyC}$) and Ly$\alpha$ (1) peak separation $v_{\rm{sep}}$, (2) ratio of the minimum flux density between the redshifted and blueshifted Ly$\alpha$ peaks to continuum flux density $f_{\rm{min}}/f_{\rm{cont}}$, and (3) equivalent width. We favor a complex \ion{H}{1} geometry to explain the Ly$\alpha$ profiles from non-LyC-leaking regions and suggest two \ion{H}{1} geometries that could diffuse and/or rescatter the central Ly$\alpha$ peak from the LyC-leaking region into our sightline across transverse distances of several hundred parsecs. Our results emphasize the complexity of Ly$\alpha$ radiative transfer and its sensitivity to the anisotropies of \ion{H}{1} gas on subgalactic scales. Large differences in the physical scales on which we observe spatially variable direct escape Ly$\alpha$, blueshifted Ly$\alpha$, and escaping LyC photons in the Sunburst Arc underscore the importance of resolving the physical scales that govern Ly$\alpha$ and LyC escape., Comment: Submitted to The Astrophysical Journal with revisions from the first referee report. Comments welcome

The hydrogen Lyman-alpha (Lya) emission line, the brightest spectral feature of a photoionized gas, is considered an indirect tracer of the escape of Lyman continuum (LyC) photons, particularly when the intergalactic medium is too opaque for direct detection. However, resonant scattering complicates interpreting the empirical properties of Lya photons, necessitating radiative transfer simulations to capture their strong coupling with underlying gas kinematics. In this study, we leverage the exceptional spatial resolution from strong gravitational lensing to investigate the connection between Lya line profiles and LyC leakage on scales of a few 100 pc in the Sunburst Arc galaxy at $z\sim2.37$. New optical echelle spectra obtained using Magellan MIKE show that both the LyC leaking and non-leaking regions exhibit a classic double-peak Lya feature with an enhanced red peak, indicating outflows at multiple locations in the galaxy. Both regions also show a central Gaussian peak atop the double peaks, indicating directly escaped Lya photons independent of LyC leakage. We introduce a machine learning-based method for emulating Lya simulations to quantify intrinsic dynamics ($\sigma_{\mathrm{int}}$), neutral hydrogen column density ($N_{\mathrm{HI}}$), outflow velocity ($v_{\mathrm{exp}}$), and effective temperature ($T$) across continuous parameter spaces. By comparing the spatially and spectrally resolved Lya lines in Sunburst, we argue that the directly escaped Lya photons originate in a volume-filling, warm ionized medium spanning $\sim1$ kpc, while the LyC leakage is confined to regions of $\lesssim200$ pc. These sub-kpc variations in Lya profiles highlight the complexity of interpreting integrated properties in the presence of inhomogeneous mixtures of gas and young stars, emphasizing the need for spatially and spectrally resolved observations of distant galaxies., Comment: 19 pages, 7 figures, 8 tables; added full names of authors; references updated

Wide-separation lensed quasars (WSLQs) are a rare class of strongly lensed quasars, magnified by foreground massive galaxy clusters, with typically large magnifications of the multiple quasar images. They are a relatively unexplored opportunity for detailed study of quasar host galaxies. The current small sample of known WSLQs has a median redshift of $z\approx 2.1$, larger than most other samples of quasar host galaxies studied to date. Here, we derive precise constraints on the properties of six WSLQs and their host galaxies, using parametric surface brightness fitting, measurements of quasar emission lines, and stellar population synthesis of host galaxies in six WSLQ systems. Our results, with significant uncertainty, indicate that these six hosts are a mixture of star-forming and quiescent galaxies. To probe for co-evolution between AGNs and host galaxies, we model the offset from the `local' ($z=0$) $M_{\rm{BH}}\unicode{x2013}M_\star$ relation as a simple power-law in redshift. Accounting for selection effects, a WSLQ-based model for evolution in the $M_{\rm{BH}}\unicode{x2013}M_\star$ relation has a power-law index of $\gamma_M=-0.42\pm0.31$, consistent with no evolution. Compared to several literature samples, which mostly probe unlensed quasars at $z<2$, the WSLQ sample shows less evolution from the local relation, at $\sim 4\sigma$. We find that selection affects and choices of $M_{\rm{BH}}$ calibration are the most important systematics in these comparisons. Given that we resolve host galaxy flux confidently even from the ground in some instances, our work demonstrates that WSLQs and highly magnified AGNs are exceptional systems for future AGN$\unicode{x2013}$host co-evolution studies., Comment: Submitted to ApJ. 25 pages + 7-page appendix, 12+4 figures. Key results are shown starting with Figure 6. Comments welcome

"Godzilla" is a peculiar object within the gravitationally lensed Sunburst Arc at $z=2.37$. Despite being very bright, it appears in only one of the twelve lensed images of the source galaxy, and shows exotic spectroscopic properties not found elsewhere in the galaxy. We use JWST's unique combination of spatial resolution and spectroscopic sensitivity to provide a unified, coherent explanation of the physical nature of Godzilla. We measure fluxes and kinematic properties of rest-optical emission lines in Godzilla and surrounding regions. Using standard line ratio-based diagnostic methods in combination with NIRCam imaging and ground based rest-UV spectra, we characterize Godzilla and its surroundings. We find that Godzilla is most likely an extremely magnified, non-erupting LBV star with dense gas condensations in close proximity. Among around 60 detected lines, we find a cascade of strong O I lines pumped by intense Ly$\beta$ emission, as well as Ly$\alpha$-pumped rest-optical Fe II lines, reminiscent of the Weigelt blobs in the local LBV star Eta Carinae. Godzilla is surrounded by dusty, inhomogeneous gas common to massive, evolved stars. Spectra and images of Godzilla and adjacent objects and the detection of a low-surface brightness foreground galaxy in the NIRCam data support the interpretation that Godzilla is a stellar-scale object extremely magnified by alignment with lensing caustics. To explain the dusty surroundings, strong [Ne III] and line kinematics simultaneously, we argue that Godzilla is a post-eruption LBV accompanied by a hotter companion and/or gas condensations exposed to more intense radiation compared to the Weigelt blobs. We expect periodic spectroscopic variations if Godzilla is a binary system. If Godzilla is confirmed to be an LBV star, it expands the distance to the furthest known LBV from a dozen Mpc to several Gpc., Comment: 18 pages, 16 figures. Submitted to A&A

We report the detection of a population of Wolf-Rayet (WR) stars in the Sunburst Arc, a strongly gravitationally lensed galaxy at redshift $z=2.37$. As the brightest known lensed galaxy, the Sunburst Arc has become an important cosmic laboratory for studying star and cluster formation, Lyman $\alpha$ radiative transfer, and Lyman Continuum (LyC) escape. Here, we present the first results of JWST/NIRSpec IFU observations of the Sunburst Arc, focusing on a stacked spectrum of the 12-fold imaged LyC-emitting (Sunburst LCE) cluster. In agreement with previous studies, we find that the cluster is massive and compact, with $M_{\text{dyn}} = (9\pm1) \times 10^{6} M_{\odot}$, Our age estimate of 4.2--4.5 Myr is much larger than the crossing time of $t_{\text{cross}} = 183 \pm 9 $ kyr, indicating that the cluster is dynamically evolved and consistent with being gravitationally bound. We find a significant nitrogen enhancement of the low ionization state ISM, with $\log(N/O) = -0.74 \pm 0.09$, which is $\approx 0.8$ dex above typical values for H II regions of similar metallicity in the local Universe. We find broad stellar emission complexes around He II$\lambda 4686$ and C IV$\lambda 5808$ with associated nitrogen emission -- this is the first time WR signatures have been directly observed at redshifts above $\sim 0.5$. The strength of the WR signatures cannot be reproduced by stellar population models that only include single-star evolution. While models with binary evolution better match the WR features, they still struggle to reproduce the nitrogen-enhanced WR features. JWST reveals the Sunburst LCE to be a highly ionized, proto-globular cluster with low oxygen abundance and extreme nitrogen enhancement that hosts a population of Wolf-Rayet stars, and possibly Very Massive stars (VMSs), which are rapidly enriching the surrounding medium., Comment: 8 pages, 4 figures, 3 tables. Accepted for publication in A&A

We compute parametric measurements of the Einstein-radius-enclosed total mass for 177 cluster-scale strong gravitational lenses identified by the ChicagO Optically-selected Lenses Located At the Margins of Public Surveys (COOL-LAMPS) collaboration with lens redshifts ranging from $0.2 \lessapprox z \lessapprox 1.0$ using only two measured parameters in each lensing system: the Einstein radius, and the brightest-cluster-galaxy (BCG) redshift. We then constrain the Einstein-radius-enclosed luminosity and stellar mass by fitting parametric spectral energy distributions (SEDs) with aperture photometry from the Dark Energy Camera Legacy Survey (DECaLS) in the $g$, $r$, and $z$-band Dark Energy Camera (DECam) filters. We find that the BCG redshift, enclosed total mass, and enclosed luminosity are strongly correlated and well described by a planar relationship in 3D space. We also find that the enclosed total mass and stellar mass are correlated with a logarithmic slope of $0.443\pm0.035$, and the enclosed total mass and stellar-to-total mass fraction are correlated with a logarithmic slope of $-0.563\pm0.035$. The correlations described here can be used to validate strong lensing candidates in upcoming imaging surveys -- such as Rubin/Legacy Survey of Space and Time (LSST) -- in which an algorithmic treatment of lensing systems will be needed due to the sheer volume of data these surveys will produce., Comment: 17 pages, 5 figures, 2 tables. Submitted to The Astrophysical Journal. v3: updated authors, formatting, grammar, and references

We present cosmological constraints from the abundance of galaxy clusters selected via the thermal Sunyaev-Zel'dovich (SZ) effect in South Pole Telescope (SPT) data with a simultaneous mass calibration using weak gravitational lensing data from the Dark Energy Survey (DES) and the Hubble Space Telescope (HST). The cluster sample is constructed from the combined SPT-SZ, SPTpol ECS, and SPTpol 500d surveys, and comprises 1,005 confirmed clusters in the redshift range $0.25-1.78$ over a total sky area of 5,200 deg$^2$. We use DES Year 3 weak-lensing data for 688 clusters with redshifts $z<0.95$ and HST weak-lensing data for 39 clusters with $0.6

This paper gives an overview of TEMPLATES, a JWST Early Release Science program that targeted four extremely bright, gravitationally lensed galaxies: two extremely dusty, two with low attenuation, as templates for galaxy evolution studies with JWST. TEMPLATES obtains a common set of spectral diagnostics for these 1.3 < z < 4.2 galaxies, in particular H alpha, Paschen alpha, and the rest-frame optical and near-infrared continua. In addition, two of the four targets have JWST coverage of [O III] 5007 Angstrom and H beta; the other two targets have have JWST coverage of PAH 3.3 micron and complementary ALMA data covering the [C II] 158 micron emission line. The science goals of TEMPLATES are to demonstrate attenuation-robust diagnostics of star formation, map the distribution of star formation, compare the young and old stellar populations, and measure the physical conditions of star formation and their spatial variation across the galaxies. In addition, TEMPLATES has technical goals to establish best practices for the Integral Field Units (IFU) within the NIRSpec and MIRI instruments, both in terms of observing strategy and in terms of data reduction. The paper describes TEMPLATES's observing program, scientific and technical goals, data reduction methods, and deliverables, including high-level data products and data reduction cookbooks., Comment: 28 pages, including 8 figures and 3 tables. Submitted to The Astrophysical Journal's Focus Issue on the TEMPLATES JWST Early Release Science Program, https://iopscience.iop.org/collections/apj-231204-01-templates

With two central galaxies engaged in a major merger and a remarkable chain of 19 young stellar superclusters wound around them in projection, the galaxy cluster SDSS J1531+3414 ($z=0.335$) offers an excellent laboratory to study the interplay between mergers, AGN feedback, and star formation. New Chandra X-ray imaging reveals rapidly cooling hot ($T\sim 10^6$ K) intracluster gas, with two "wings" forming a concave density discontinuity near the edge of the cool core. LOFAR $144$ MHz observations uncover diffuse radio emission strikingly aligned with the "wings," suggesting that the "wings" are actually the opening to a giant X-ray supercavity. The steep radio emission is likely an ancient relic of one of the most energetic AGN outbursts observed, with $4pV > 10^{61}$ erg. To the north of the supercavity, GMOS detects warm ($T\sim 10^4$ K) ionized gas that enshrouds the stellar superclusters but is redshifted up to $+ 800$ km s$^{-1}$ with respect to the southern central galaxy. ALMA detects a similarly redshifted $\sim 10^{10}$ M$_\odot$ reservoir of cold ($T\sim 10^2$ K) molecular gas, but it is offset from the young stars by $\sim 1{-}3$ kpc. We propose that the multiphase gas originated from low-entropy gas entrained by the X-ray supercavity, attribute the offset between the young stars and the molecular gas to turbulent intracluster gas motions, and suggest that tidal interactions stimulated the "beads on a string" star formation morphology., Comment: Accepted by ApJ, 36 pages, 23 figures

We present six strongly gravitationally lensed Ly-$\alpha$ Emitters (LAEs) at $z\sim4-5$ with HST narrowband imaging isolating Ly-$\alpha$. Through complex radiative transfer Ly-$\alpha$ encodes information about the spatial distribution and kinematics of the neutral hydrogen upon which it scatters. We investigate the galaxy properties and Ly-$\alpha$ morphologies of our sample. Many previous studies of high-redshift LAEs have been limited in Ly-$\alpha$ spatial resolution. In this work we take advantage of high-resolution Ly-$\alpha$ imaging boosted by lensing magnification, allowing us to probe sub-galactic scales that are otherwise inaccessible at these redshifts. We use broadband imaging from HST (rest-frame UV) and Spitzer (rest-frame optical) in SED fitting; providing estimates on the stellar masses ($\sim 10^8 - 10^9 M_{\odot}$), stellar population ages ($t_{50} <40$ Myr), and amounts of dust ($A_V \sim 0.1 - 0.6$, statistically consistent with zero). We employ non-parametric star-formation histories to probe the young stellar-populations which create Ly-$\alpha$. We also examine the offsets between the Ly-$\alpha$ and stellar continuum, finding small upper limits of offsets ($< 0.1"$) consistent with studies of low-redshift LAEs; indicating our galaxies are not interacting or merging. Finally, we find a bimodality in our sample's Ly-$\alpha$ morphologies: clumpy and extended. We find a suggestive trend: our LAEs with clumpy Ly-$\alpha$ are generally younger than the LAEs with extended Ly-$\alpha$, suggesting a possible correlation with age., Comment: 17 pages (2 for references), 5 figures, 6 tables

Through observational tests of strong lensing galaxy clusters, we can test simulation derived structure predictions that follow from $\Lambda$ Cold Dark Matter ($\Lambda$CDM) cosmology. The shape and centroid deviations between the total matter distribution, stellar matter distributions, and hot intracluster gas distribution serve as an observational test of these theoretical structure predictions. We measure the position angles, ellipticities, and locations/centroids of the brightest cluster galaxy (BCG), intracluster light (ICL), the hot intracluster medium (ICM), and the core lensing mass for a sample of strong lensing galaxy clusters from the SDSS Giant Arcs Survey (SGAS). We utilize HST WFC3/IR imaging data to measure the shapes/centroids of the ICL and BCG distributions and use Chandra ACIS-I X-ray data to measure the shapes/centroids of ICM. Additionally, we measure the concentration parameter c and asymmetry parameter A to incorporate cluster dynamical state into our analysis. Using this multicomponent approach, we attempt to constrain the astrophysics of our strong lensing cluster sample and evaluate the different components in terms of their ability to trace out the DM halo of clusters in various dynamical states., Comment: 6 pages, 4 figures, to appear in Proc. of the mm Universe 2023 conference, Grenoble (France), June 2023, published by F. Mayet et al. (Eds), EPJ Web of conferences, EDP Sciences

We present a Bayesian population modeling method to analyze the abundance of galaxy clusters identified by the South Pole Telescope (SPT) with a simultaneous mass calibration using weak gravitational lensing data from the Dark Energy Survey (DES) and the Hubble Space Telescope (HST). We discuss and validate the modeling choices with a particular focus on a robust, weak-lensing-based mass calibration using DES data. For the DES Year 3 data, we report a systematic uncertainty in weak-lensing mass calibration that increases from 1% at $z=0.25$ to 10% at $z=0.95$, to which we add 2% in quadrature to account for uncertainties in the impact of baryonic effects. We implement an analysis pipeline that joins the cluster abundance likelihood with a multi-observable likelihood for the Sunyaev-Zel'dovich effect, optical richness, and weak-lensing measurements for each individual cluster. We validate that our analysis pipeline can recover unbiased cosmological constraints by analyzing mocks that closely resemble the cluster sample extracted from the SPT-SZ, SPTpol ECS, and SPTpol 500d surveys and the DES Year 3 and HST-39 weak-lensing datasets. This work represents a crucial prerequisite for the subsequent cosmological analysis of the real dataset., Comment: Accepted for publication in Phys. Rev. D. arXiv v2 corresponds to published article

We present an extension to a Sunyaev-Zel'dovich Effect (SZE) selected cluster catalog based on observations from the South Pole Telescope (SPT); this catalog extends to lower signal-to-noise than the previous SPT-SZ catalog and therefore includes lower mass clusters. Optically derived redshifts, centers, richnesses and morphological parameters together with catalog contamination and completeness statistics are extracted using the multi-component matched filter algorithm (MCMF) applied to the S/N>4 SPT-SZ candidate list and the Dark Energy Survey (DES) photometric galaxy catalog. The main catalog contains 811 sources above S/N=4, has 91% purity and is 95% complete with respect to the original SZE selection. It contains 50% more total clusters and twice as many clusters above z=0.8 in comparison to the original SPT-SZ sample. The MCMF algorithm allows us to define subsamples of the desired purity with traceable impact on catalog completeness. As an example, we provide two subsamples with S/N>4.25 and S/N>4.5 for which the sample contamination and cleaning-induced incompleteness are both as low as the expected Poisson noise for samples of their size. The subsample with S/N>4.5 has 98% purity and 96% completeness, and will be included in a combined SPT cluster and DES weak-lensing cosmological analysis. We measure the number of false detections in the SPT-SZ candidate list as function of S/N, finding that it follows that expected from assuming Gaussian noise, but with a lower amplitude compared to previous estimates from simulations., Comment: 16 pages, 17 figures, submitted to MNRAS

We present the spatially resolved measurements of a cool galactic outflow in the gravitationally lensed galaxy RCS0327 at $z \approx 1.703$ using VLT/MUSE IFU observations. We probe the cool outflowing gas, traced by blueshifted Mg II and Fe II absorption lines, in 15 distinct regions of the same galaxy in its image-plane. Different physical regions, 5 to 7 kpc apart within the galaxy, drive the outflows at different velocities ($V_{out} \sim $ $-161$ to $-240$ km s$^{-1}$), and mass outflow rates ($\dot{M}_{out} \sim$ 183 to 527 $M_{\odot}\ yr^{-1}$). The outflow velocities from different regions of the same galaxy vary by 80 km s$^{-1}$, which is comparable to the variation seen in a large sample of star-burst galaxies in the local Universe. Using multiply lensed images of RCS0327, we probe the same star-forming region at different spatial scales (0.5 kpc$^2$-25 kpc$^2$), we find that outflow velocities vary between $ \sim $ $-120$ to $-242$ km s$^{-1}$, and the mass outflow rates vary between $\sim$ 37 to 254 $M_{\odot}\ yr^{-1}$. The outflow momentum flux in this galaxy is $\geq$ 100% of the momentum flux provided by star-formation in individual regions, and outflow energy flux is $\approx$ 10% of the total energy flux provided by star-formation. These estimates suggest that the outflow in RCS0327 is energy driven. This work shows the importance of small scale variations of outflow properties due to the variations of local stellar properties of the host galaxy in the context of galaxy evolution., Comment: 26 pages, 15 figures, 6 tables, accepted for publication in MNRAS, the referee comments are incorporated in this version

We report the discovery of COOL J0335$-$1927, a quasar at z = 3.27 lensed into three images with a maximum separation of 23.3" by a galaxy cluster at z = 0.4178. To date this is the highest redshift wide-separation lensed quasar known. In addition, COOL J0335$-$1927 shows several strong intervening absorbers visible in the spectra of all three quasar images with varying equivalent width. The quasar also shows mini-broad line absorption. We construct a parametric strong gravitational lens model using ground-based imaging, constrained by the redshift and positions of the quasar images as well as the positions of three other multiply-imaged background galaxies. Using our best-fit lens model, we calculate the predicted time delays between the three quasar images to be $\Delta$t$_{AB}=$ $499^{+141}_{-146}$ (stat) and $\Delta$t$_{AC}=$ $-127^{+83}_{-17}$ (stat) days. Folding in systematic uncertainties, the model-predicted time delays are within the ranges $240 < \Delta$t$_{AB} < 700$ and $-300 < \Delta$ t$_{AC} <-30$. We also present g-band photometry from archival DECaLS and Pan-STARRS imaging, and new multi-epoch observations obtained between September 18, 2022 UT and February 22, 2023 UT, which demonstrate significant variability in the quasar and which will eventually enable a measurement of the time delay between the three quasar images. The currently available light curves are consistent with the model-predicted time delays. This is the fifth paper from the COOL-LAMPS collaboration., Comment: 8 pages, 4 figures, 1 table

Extreme, young stellar populations are considered the primary contributor to cosmic re-ionization. How Lyman-continuum (LyC) escapes these galaxies remains highly elusive, and it is challenging to observe this process in actual LyC emitters without resolving the relevant physical scales. We investigate the Sunburst Arc: a strongly lensed, LyC emitter at $z =2.37$ that reveals an exceptionally small scale (tens of parsecs) region of high LyC escape. The small ($<$ 100 pc) LyC leaking region has extreme properties: a very blue UV slope ($\beta = -2.9 \pm 0.1$), high ionization state ([O III]$\lambda 5007$/[O II]$\lambda 3727 $ $= 11 \pm 3$ and [O III]$\lambda 5007$/H$\beta$ $=6.8 \pm 0.4$), strong oxygen emission (EW([O III]) $= 1095 \pm 40 \ \r{A}$), and high Lyman-$\alpha$ escape fraction ($0.3 \pm 0.03$), none of which are found in non-leaking regions of the galaxy. The leaking region's UV slope is consistent with approximately ``pure'' stellar light that is minimally contaminated by surrounding nebular continuum emission or extinguished by dust. These results suggest a highly anisotropic LyC escape process such that LyC is produced and escapes from a small, extreme starburst region where the stellar feedback from an ionizing star cluster creates one or more ``pencil beam'' channels in the surrounding gas through which LyC can directly escape. Such anisotropic escape processes imply that random sightline effects drive the significant scatters between measurements of galaxy properties and LyC escape fraction, and that strong lensing is a critical tool for resolving the processes that regulate the ionizing budget of galaxies for re-ionization., Comment: 19 pages, 7 figures, 3 tables, Accepted for publication by ApJL

We present the discovery of the most distant, dynamically relaxed cool core cluster, SPT-CL J2215-3537 (SPT2215) and its central brightest cluster galaxy (BCG) at z=1.16. Using new X-ray observations, we demonstrate that SPT2215 harbors a strong cool core, with a central cooling time of 200 Myr (at 10 kpc) and a maximal intracluster medium cooling rate of 1900+/-400 Msun/yr. This prodigious cooling may be responsible for fueling extended, star-forming filaments observed in Hubble Space Telescope imaging. Based on new spectrophotometric data, we detect bright [O II] emission in the BCG, implying an unobscured star formation rate (SFR) of 320^{+230}_{-140} Msun/yr. The detection of a weak radio source (2.0+/-0.8 mJy at 0.8 GHz) suggests ongoing feedback from an active galactic nucleus (AGN), though the implied jet power is less than half the cooling luminosity of the hot gas, consistent with cooling overpowering heating. The extreme cooling and SFR of SPT2215 is rare among known cool core clusters, and it is even more remarkable that we observe these at such high redshift, when most clusters are still dynamically disturbed. The high mass of this cluster, coupled with the fact that it is dynamically relaxed with a highly-isolated BCG, suggests that it is an exceptionally rare system that must have formed very rapidly in the early Universe. Combined with the high SFR, SPT2215 may be a high-z analog of the Phoenix cluster, potentially providing insight into the limits of AGN feedback and star formation in the most massive galaxies., Comment: 14 pages, 5 figures, 1 table. Accepted in ApJ

Tension between cosmic microwave background-based and distance ladder-based determinations of the Hubble constant ${\rm H}_{\rm 0}$ motivates pursuit of independent methods that are not subject to the same systematic effects. A promising alternative, proposed by Refsdal in 1964, relies on the inverse scaling of ${\rm H}_{\rm 0}$ with the delay between the arrival times of at least two images of a strongly-lensed variable source such as a quasar. To date, Refsdal's method has mostly been applied to quasars lensed by individual galaxies rather than by galaxy clusters. Using the three quasars strongly lensed by galaxy clusters (SDSS J1004+4112, SDSS J1029+2623, and SDSS J2222+2745) that have both multiband Hubble Space Telescope data and published time delay measurements, we derive ${\rm H}_{\rm 0}$, accounting for the systematic and statistical sources of uncertainty. While a single time delay measurement does not yield a well-constrained ${\rm H}_{\rm 0}$ value, analyzing the systems together tightens the constraint. Combining the six time delays measured in the three cluster-lensed quasars gives ${\rm H}_{\rm 0}$ = 74.1 $\pm$ 8.0 km s$^{-1}$ Mpc$^{-1}$. To reach 1$\%$ uncertainty in ${\rm H}_{\rm 0}$, we estimate that a sample size of order of 620 time delay measurements of similar quality as those from SDSS J1004+4112, SDSS J1029+2623, and SDSS J2222+2745 would be needed. Improving the lens modeling uncertainties by a factor of two and a half may reduce the needed sample size to 100 time delays, potentially reachable in the next decade., Comment: 14 pages, 2 figures

We report the discovery of five bright strong gravitationally lensed galaxies at $3 < z < 4$: COOLJ0101$+$2055 ($z = 3.459$), COOLJ0104$-$0757 ($z = 3.480$), COOLJ0145$+$1018 ($z = 3.310$), COOLJ0516$-$2208 ($z = 3.549$), and COOLJ1356$+$0339 ($z = 3.753$). These galaxies have magnitudes of $r_{\rm AB}, z_{\rm AB} < 21.81$ mag and are lensed by galaxy clusters at $0.26 < z < 1$. This sample nearly doubles the number of known bright lensed galaxies with extended arcs at $3 < z < 4$. We characterize the lensed galaxies using ground-based grz/giy imaging and optical spectroscopy. We report model-based magnitudes and derive stellar masses, dust content, and star-formation rates via stellar population synthesis modeling. Building lens models based on ground-based imaging, we estimate source magnifications in the range $\sim$29 to $\sim$180. Combining these analyses, we derive demagnified stellar masses in the range $\rm log_{10}(M_{*}/M_{\odot}) \sim 9.69 - 10.75$ and star formation rates in the youngest age bin ranging from $\rm log_{10}(SFR/(M_{\odot}\cdot yr^{-1})) \sim 0.39 - 1.46$, placing the sample galaxies on the massive end of the star-forming main sequence in this redshift interval. In addition, three of the five galaxies have strong Ly$\alpha$ emissions, offering unique opportunities to study Ly$\alpha$ emitters at high redshift in future work., Comment: 20 pages, 10 figures

We analyze spectra of a gravitationally lensed galaxy, known as the Sunburst Arc, that is leaking ionizing photons, also known as the Lyman continuum (LyC). Magnification from gravitational lensing permits the galaxy to be spatially resolved into one region that leaks ionizing photons, and several that do not. Rest-frame ultraviolet and optical spectra from Magellan target ten different regions along the lensed Arc, including six multiple images of the LyC leaking region, as well as four regions that do not show LyC emission. The rest-frame optical spectra of the ionizing photon emitting regions reveal a blue-shifted ($\Delta V$=27 km s$^{-1}$) broad emission component (FWHM=327 km s$^{-1}$) comprising 55% of the total [OIII] line flux, in addition to a narrow component (FWHM = 112 km s$^{-1}$), suggesting the presence of strong highly ionized gas outflows. This is consistent with the high-velocity ionized outflow inferred from the rest-frame UV spectra. In contrast, the broad emission component is less prominent in the non-leaking regions, comprising $\sim$26% of total [OIII] line flux. The high ionization absorption lines are prominent in both leaker and non-leaker but low ionization absorption lines are very weak in the leaker, suggesting that the line of sight gas is highly ionized in the leaker. Analyses of stellar wind features reveal that the stellar population of the LyC leaking regions is considerably younger ($\sim$3 Myr) than the non-leaking regions ($\sim$12 Myr), highlighting that stellar feedback from young stars may play an important role in ionizing photon escape., Comment: Accepted for publication in ApJ

In the third paper from the COOL-LAMPS Collaboration, we report the discovery of COOL J0542-2125, a gravitationally lensed quasar at $z=1.84$, observed as three images due to an intervening massive galaxy cluster at $z=0.61$. The lensed quasar images were identified in a search for lens systems in recent public optical imaging data and have separations on the sky up to 25".9, wider than any previously known lensed quasar. The galaxy cluster acting as a strong lens appears to be in the process of merging, with two sub-clusters separated by $\sim 1$ Mpc in the plane of the sky, and their central galaxies showing a radial velocity difference of $\sim 1000$ km/s. Both cluster cores show strongly lensed images of an assortment of background sources, as does the region between them. A preliminary strong lens model implies masses of $M(<250\ \rm{kpc}) = 1.79^{+0.16} _{-0.01} \times 10^{14} M_{\odot}$ and $M(<250\ \rm{kpc}) = 1.48^{+0.04}_{-0.10} \times 10^{14} M_{\odot}$ for the East and West sub-clusters, respectively. This line of sight is also coincident with a ROSAT ALL-sky Survey source, centered between the two confirmed cluster halos reminiscent of other major cluster-scale mergers., Comment: 13 pages, 6 figures. Submitted to ApJ

We present a strong lensing analysis of the cluster PSZ1 G311.65-18.48, based on Hubble Space Telescope imaging, archival VLT/MUSE spectroscopy, and Chandra X-ray data. This cool-core cluster (z=0.443) lenses the brightest lensed galaxy known, dubbed the "Sunburst Arc" (z=2.3703), a Lyman continuum (LyC) emitting galaxy multiply-imaged 12 times. We identify in this field 14 additional strongly-lensed galaxies to constrain a strong lens model, and report secure spectroscopic redshifts of four. We measure a projected cluster core mass of M(<250 kpc)=2.93+0.01/-0.02x10^14M_sun. The two least-magnified but complete images of the Sunburst Arc's source galaxy are magnified by ~13x, while the LyC clump is magnified by ~4-80x. We present time delay predictions and conclusive evidence that a discrepant clump in the Sunburst Arc, previously claimed to be a transient, is not variable, thus strengthening the hypothesis that it results from an exceptionally high magnification. A source plane reconstruction and analysis of the Sunburst Arc finds its physical size to be 1x2 kpc, and that it is resolved in three distinct directions in the source plane, 0, 40, and 75 degrees (east of North). We place an upper limit of r <~ 50 pc on the source plane size of unresolved clumps, and r<~ 32 pc for the LyC clump. Finally, we report that the Sunburst Arc is likely in a system of two or more galaxies separated by <~6 kpc in projection. Their interaction may drive star formation and could play a role in the mechanism responsible for the leaking LyC radiation., Comment: 31 pages, 14 figures, 4 tables. Submitted to ApJ

We present a Hubble Space Telescope (HST) weak gravitational lensing study of nine distant and massive galaxy clusters with redshifts $1.0 \lesssim z \lesssim 1.7$ ($z_\mathrm{median} = 1.4$) and Sunyaev Zel'dovich (SZ) detection significance $\xi > 6.0$ from the South Pole Telescope Sunyaev Zel'dovich (SPT-SZ) survey. We measured weak lensing galaxy shapes in HST/ACS F606W and F814W images and used additional observations from HST/WFC3 in F110W and VLT/FORS2 in $U_\mathrm{HIGH}$ to preferentially select background galaxies at $z\gtrsim 1.8$, achieving a high purity. We combined recent redshift estimates from the CANDELS/3D-HST and HUDF fields to infer an improved estimate of the source redshift distribution. We measured weak lensing masses by fitting the tangential reduced shear profiles with spherical Navarro-Frenk-White (NFW) models. We obtained the largest lensing mass in our sample for the cluster SPT-CLJ2040$-$4451, thereby confirming earlier results that suggest a high lensing mass of this cluster compared to X-ray and SZ mass measurements. Combining our weak lensing mass constraints with results obtained by previous studies for lower redshift clusters, we extended the calibration of the scaling relation between the unbiased SZ detection significance $\zeta$ and the cluster mass for the SPT-SZ survey out to higher redshifts. We found that the mass scale inferred from our highest redshift bin ($1.2 < z < 1.7$) is consistent with an extrapolation of constraints derived from lower redshifts, albeit with large statistical uncertainties. Thus, our results show a similar tendency as found in previous studies, where the cluster mass scale derived from the weak lensing data is lower than the mass scale expected in a Planck $\nu\Lambda$CDM (i.e. $\nu$ $\Lambda$ Cold Dark Matter) cosmology given the SPT-SZ cluster number counts., Comment: 23 pages, 10 figures + appendix (9 pages, 9 figures); accepted for publication in A&A

The strongly lensed z=2.9233 Lyman break galaxy, SGAS J122651.3+215220, lensed by a cluster at z=0.4358, was first targeted by JWST as part of the JWST-ERS program TEMPLATES: Targeting Extremely Magnified Panchromatic Lensed Arcs and their Extended Star formation. Aiming to combine the exquisite capabilities of JWST with the extreme magnification provided by strong gravitational lensing, these observations will peer into galaxies at cosmic noon and probe the building blocks of star formation. Here, we present an Hubble Space Telescope strong lensing analysis, lens model, source-plane interpretation, and the lensing outputs needed to analyze the JWST observations in the context of the source's intrinsic properties. The lens model outputs are made publicly available to the community through the Mikulski Archive for Space Telescopes (MAST) Portal., Comment: 15 pages, 7 figures. HLSPs are available on MAST at http://dx.doi.org/10.17909/zqax-2y86

Spatially extended halos of H I Ly$\alpha$ emission are now ubiquitously found around high-redshift star-forming galaxies. But our understanding of the nature and powering mechanisms of these halos is still hampered by the complex radiative transfer effects of the Ly$\alpha$ line and limited angular resolution. In this paper, we present resolved Multi Unit Spectroscopic Explorer (MUSE) observations of SGAS J122651.3+215220, a strongly-lensed pair of $L^{*}$ galaxies at $z=2.92$ embedded in a Ly$\alpha$ halo of $L_{Ly\alpha}=(6.2\pm1.3)\times10^{42}$ erg s$^{-1}$. Globally, the system shows a line profile that is markedly asymmetric and redshifted, but its width and peak shift vary significantly across the halo. By fitting the spatially binned Ly$\alpha$ spectra with a collection of radiative transfer galactic wind models, we infer a mean outflow expansion velocity of $\approx 211$ km s$^{-1}$, with higher values preferentially found on both sides of the system's major axis. The velocity of the outflow is validated with the blueshift of low-ionization metal absorption lines in the spectra of the central galaxies. We also identify a faint ($M_{1500} \approx -16.7$) companion detected in both Ly$\alpha$ and the continuum, whose properties are in agreement with a predicted population of satellite galaxies that contribute to the extended Ly$\alpha$ emission. Finally, we briefly discuss the impact of the interaction between the central galaxies on the properties of the halo and the possibility of in situ fluorescent Ly$\alpha$ production., Comment: Published in ApJ. 26 pages, 14 figures

We present COOL J1323+0343, an early-type galaxy at $z = 1.0153 \pm 0.0006$, strongly lensed by a cluster of galaxies at z = $z = 0.353 \pm 0.001$. This object was originally imaged by DECaLS and noted as a gravitational lens by COOL-LAMPS, a collaboration initiated to find strong-lensing systems in recent public optical imaging data, and confirmed with follow-up data. With ground-based grzH imaging and optical spectroscopy from the Las Campanas Observatory and the Nordic Optical Telescope, we derive a stellar mass, metallicity, and star-formation history from stellar-population synthesis modeling. The lens modeling implies a total magnification of $\mu \sim $113. The median remnant stellar mass in the source plane is M$_* \sim 10.63$ $M_\odot$ and the median star-formation rate in the source plane is SFR $\sim 1.55 \times 10^{-3}$ M$_\odot$ yr$^{-1}$ (log sSFR = -13.4 yr$^{-1}$) in the youngest two age bins (0-100 Myr), closest to the epoch of observation. Our measurements place COOL J1323+0343 below the characteristic mass of the stellar mass function, making it an especially compelling target that could help clarify how intermediate mass quiescent galaxies evolve. We reconstruct COOL J1323+0343 in the source plane and fit its light profile. This object is below the expected size-evolution of early-type galaxy at this mass with an effective radius r$_e \sim$ 0.5 kpc. This extraordinarily magnified and bright lensed early-type galaxy offers an exciting opportunity to study the morphology and star formation history of an intermediate mass early-type galaxy in detail at $z \sim $1 ., Comment: Submitted to the Astrophysical Journal. 11 pages, 7 figures, and 2 tables. Feedback welcome

Using stellar population synthesis models to infer star formation histories (SFHs), we analyse photometry and spectroscopy of a large sample of quiescent galaxies which are members of Sunyaev-Zel'dovich (SZ)-selected galaxy clusters across a wide range of redshifts. We calculate stellar masses and mass-weighted ages for 837 quiescent cluster members at 0.3 < z < 1.4 using rest-frame optical spectra and the Python-based Prospector framework, from 61 clusters in the SPT-GMOS Spectroscopic Survey (0.3 < z < 0.9) and 3 clusters in the SPT Hi-z cluster sample (1.25 < z < 1.4). We analyse spectra of subpopulations divided into bins of redshift, stellar mass, cluster mass, and velocity-radius phase-space location, as well as by creating composite spectra of quiescent member galaxies. We find that quiescent galaxies in our dataset sample a diversity of SFHs, with a median formation redshift (corresponding to the lookback time from the redshift of observation to when a galaxy forms 50% of its mass, t$_{50}$) of $z=2.8\pm0.5$, which is similar to or marginally higher than that of massive quiescent field and cluster galaxy studies. We also report median age-stellar mass relations for the full sample (age of the Universe at $t_{50}$ (Gyr) = $2.52 (\pm0.04) - 1.66 (\pm0.11)$ log$_{10}(M/10^{11} M\odot))$ and recover downsizing trends across stellar mass; we find that massive galaxies in our cluster sample form on aggregate $\sim0.75$ Gyr earlier than lower mass galaxies. We also find marginally steeper age-mass relations at high redshifts, and report a bigger difference in formation redshifts across stellar mass for fixed environment, relative to formation redshifts across environment for fixed stellar mass., Comment: 35 pages, 23 figures, 5 tables. Submitted to The Astrophysical Journal. Comments and feedback welcome

We image the spatial extent of a cool galactic outflow with fine structure Fe II$^*$ emission and resonant Mg II emission in a gravitationally lensed star-forming galaxy at $z = 1.70347$. The Fe II$^*$ and Mg II (continuum-subtracted) emissions span out to radial distances of $\sim$14.33 kpc and 26.5 kpc, respectively, with maximum spatial extents of $\sim$21 kpc for Fe II$^*$ emission and $\sim$30 kpc for Mg II emission. Mg II residual emission is patchy and covers a total area of $\sim$184 kpc$^2$, constraining the minimum area covered by the outflowing gas to be $\sim$13% of the total area. Mg II emission is asymmetric and shows $\sim$21% more extended emission along the declination direction. We constrain the covering fractions of the Fe II$^*$ and Mg II emission as a function of radial distance and characterize them with a power law model. The Mg II 2803 emission line shows two kinematically distinct emission components, and may correspond to two distinct shells of outflowing gas with a velocity separation of $\Delta v \sim$ 400 km/s. By using multiple images with different magnifications of the galaxy in the image plane, we trace the Fe II$^*$, Mg II emissions around three individual star-forming regions. In all cases, both the Fe II$^*$ and Mg II emissions are more spatially extended compared to the star forming regions traced by the [O II] emission. These findings provide robust constraints on the spatial extent of the outflowing gas, and combined with outflow velocity and column density measurements will give stringent constraints on mass outflow rates of the galaxy., Comment: 22 pages, 14 figures, 4 tables, accepted to ApJ, the referee comments are incorporated in this version

Star-forming galaxies (SFGs) with stellar masses below $10^{10}\,M_\odot$ make up the bulk of the galaxy population at $z>2$. The properties of the cold gas in these galaxies can only be probed in very deep ALMA observations or by targeting strongly lensed galaxies. Here we report the results of a pilot survey using the Atacama Compact Array (ACA) of molecular gas in the most strongly magnified galaxies selected as giant arcs in optical data. The selection in rest-frame UV wavelengths ensures that sources are regular star forming galaxies, without a priori indications of intense dusty starburst activity. We conducted Band 4 and Band 7 observations to detect mid-$J$ CO, [C I] and thermal continuum as molecular gas tracers from four strongly lensed systems at $z\approx2-3$: our targets are SGAS J1226651.3+215220 (A and B), SGAS J003341.5+024217 and the Sunburst Arc. The measured molecular mass is then projected onto the source plane with detailed lens models developed from high resolution HST observations. Multiwavelength photometry is then used to obtain the intrinsic stellar mass and star formation rate via SED fitting. In only one of the sources are the three tracers robustly detected, while in the others they are either undetected or detected in continuum only. The implied molecular gass masses range from $4\times 10^{9}\,M_\odot$ in the detected source to an upper limit of $\lesssim 10^9\,M_\odot$ in the most magnified source. The inferred gas fraction and gas depletion timescale are found to lie approximately 0.5 to 1.0 dex below the established scaling relations based on previous studies of unlensed massive galaxies. Our results indicate that the cold gas content of intermediate to low mass galaxies should not be extrapolated from the trends seen in more massive high-$z$ galaxies. (Abridged abstract), Comment: 17 pages, 7 figures. Accepted for publication in Astronomy & Astrophysics

The core mass of galaxy clusters is both an important anchor of the radial mass distribution profile and probe of structure formation. With thousands of strong lensing galaxy clusters being discovered by current and upcoming surveys, timely, efficient, and accurate core mass estimates are needed. We assess the results of two efficient methods to estimate the core mass of strong lensing clusters: the mass enclosed by the Einstein radius ($M_{corr}(<\theta_E)$ where $\theta_{\rm E}$ is approximated from arc positions; Remolina Gonz\'{a}lez et al. 2020), and single-halo lens model ($M_{\rm{SHM}}(<\rm{e}\theta_{\rm{E}})$; Remolina Gonz\'{a}lez et al. 2021), against measurements from publicly available detailed lens models ($M_{\rm{DLM}}$) of the same clusters. We use data from the Sloan Giant Arc Survey, the Reionization Lensing Cluster Survey, the \Hubble\ Frontier Fields, and the Cluster Lensing and Supernova Survey with \Hubble. We find a scatter of $18.3\%$ ($8.4\%$) with a bias of $-7.5\%$ ($0.4\%$) between $M_{corr}(<\theta_E)$ ($M_{\rm{SHM}}(<\rm{e}\theta_{\rm{E}})$) and $M_{\rm{DLM}}$. Last, we compare the statistical uncertainties measured in this work to those from simulations. This work demonstrates the successful application of these methods to observational data. As the effort to efficiently model the mass distribution of strong lensing galaxy clusters continues, we need fast, reliable methods to advance the field.

The See Change survey was designed to make $z>1$ cosmological measurements by efficiently discovering high-redshift Type Ia supernovae (SNe Ia) and improving cluster mass measurements through weak lensing. This survey observed twelve galaxy clusters with the Hubble Space Telescope spanning the redshift range $z=1.13$ to $1.75$, discovering 57 likely transients and 27 likely SNe Ia at $z\sim 0.8-2.3$. As in similar previous surveys (Dawson et al. 2009), this proved to be a highly efficient use of HST for SN observations; the See Change survey additionally tested the feasibility of maintaining, or further increasing, the efficiency at yet higher redshifts, where we have less detailed information on the expected cluster masses and star-formation rates. We find that the resulting number of SNe Ia per orbit is a factor of $\sim 8$ higher than for a field search, and 45% of our orbits contained an active SN Ia within 22 rest-frame days of peak, with one of the clusters by itself yielding 6 of the SNe Ia. We present the survey design, pipeline, and SN discoveries. Novel features include fully blinded SN searches, the first random forest candidate classifier for undersampled IR data (with a 50% detection threshold within 0.05 magnitudes of human searchers), real-time forward-modeling photometry of candidates, and semi-automated photometric classifications and follow-up forecasts. We also describe the spectroscopic follow-up, instrumental in measuring host-galaxy redshifts. The cosmology analysis of our sample will be presented in a companion paper., Comment: ApJ preprint

We present CIV BLR modeling results for the multiply imaged $z=2.805$ quasar SDSS J2222+2745. Using data covering a 5.3 year baseline after accounting for gravitational time delays, we find models that can reproduce the observed emission-line spectra and integrated CIV fluctuations. The models suggest a thick disk BLR that is inclined by $\sim$40 degrees to the observer's line of sight and with a emissivity weighted median radius of $r_{\rm median} = 33.0^{+2.4}_{-2.1}$ light days. The kinematics are dominated by near-circular Keplerian motion with the remainder inflowing. The rest-frame lag one would measure from the models is $\tau_{\rm median} = 36.4^{+1.8}_{-1.8}$ days, which is consistent with measurements based on cross-correlation. We show a possible geometry and transfer function based on the model fits and find that the model-produced velocity-resolved lags are consistent with those from cross-correlation. We measure a black hole mass of $\log_{10}(M_{\rm BH}/M_\odot) = 8.31^{+0.07}_{-0.06}$, which requires a scale factor of $\log_{10}(f_{{\rm mean},\sigma}) = 0.20^{+0.09}_{-0.07}$., Comment: 8 pages, 5 figures, submitted to ApJL

The core mass of galaxy clusters is an important probe of structure formation. Here, we evaluate the use of a Single-Halo model (SHM) as an efficient method to estimate the strong lensing cluster core mass, testing it with ray-traced images from the `Outer Rim' simulation. Unlike detailed lens models, the SHM represents the cluster mass distribution with a single halo and can be automatically generated from the measured lensing constraints. We find that the projected core mass estimated with this method, M$_{\rm SHM}$, has a scatter of $8.52\%$ and a bias of $0.90\%$ compared to the "true" mass within the same aperture. Our analysis shows no systematic correlation between the scatter or bias and the lens-source system properties. The bias and scatter can be reduced to $3.26\%$ and $0.34\%$, respectively, by excluding models that fail a visual inspection test. We find that the SHM success depends on the lensing geometry, with single giant arc configurations accounting for most of the failed cases due to their limiting constraining power. When excluding such cases, we measure a scatter and bias of $3.88\%$ and $0.84\%$, respectively. Finally, we find that when the source redshift is unknown, the model-predicted redshifts are overestimated, and the M$_{\rm SHM}$ is underestimated by a few percent, highlighting the importance of securing spectroscopic redshifts of background sources. Our analysis provides a quantitative characterization of M$_{\rm SHM}$, enabling its efficient use as a tool to estimate the strong lensing cluster core masses in the large samples, expected from current and future surveys.

We report the discovery of COOL J1241+2219, a strongly-lensed galaxy at redshift $z$=5.043$\pm$0.002 with observed magnitude $z_{AB}=20.47$, lensed by a moderate-mass galaxy cluster at $z$=1.001$\pm$0.001. COOL J1241+2219 is the brightest lensed galaxy currently known at optical and near-infrared wavelengths at $z$ $\gtrsim$ 5; it is $\sim$5 times brighter than the prior record-holder lensed galaxy, and several magnitudes brighter than the brightest unlensed galaxies known at these redshifts. It was discovered as part of COOL-LAMPS, a collaboration initiated to find strongly lensed systems in recent public optical imaging data. We characterise the lensed galaxy, as well as the central galaxy of the lensing cluster using ground-based $griz$JH imaging and optical spectroscopy. We report model-based magnitudes, and derive stellar masses, dust content, metallicity and star-formation rates via stellar-population synthesis modeling. Our lens mass modeling, based on ground-based imaging, implies a median source magnification of $\sim$30, which puts the stellar mass and star formation rate (in the youngest age bin, closest to the epoch of observation) at logM$_{*}$ = $10.11^{+0.21}_{-0.26}$ and SFR = $27^{+13}_{-9}$ M$_{\odot}$/yr, respectively. We constrain a star formation history for COOL J1241+2219 consistent with constant star formation across $\sim$1 Gyr of cosmic time, and that places this galaxy on the high-mass end of the star-forming main sequence. COOL J1241+2219 is 2-4 times more luminous than a galaxy with the characteristic UV luminosity at these redshifts. The UV continuum slope $\beta$= -2.2$\pm$0.2 places this galaxy on the blue side of the observed distribution of galaxies at $z$=5, although the lack of Ly$\alpha$ emission indicates dust sufficient to suppress this emission., Comment: Accepted in the Astrophysical Journal, December 2020 (in production). 16 pages, 7 figures, 2 tables

We present the first results of a 4.5 year monitoring campaign of the three bright images of multiply imaged $z=2.805$ quasar SDSS J2222+2745 using the Gemini North Multi-Object Spectrograph (GMOS-N) and the Nordic Optical Telescope (NOT). We take advantage of gravitational time delays to construct light curves surpassing 6 years in duration and achieve average spectroscopic cadence of 10 days during the 8 months of visibility per season. Using multiple secondary calibrators and advanced reduction techniques, we achieve percent-level spectrophotometric precision and carry out an unprecedented reverberation mapping analysis, measuring both integrated and velocity-resolved time lags for CIV. The full line lags the continuum by $\tau_{\rm cen} = 36.5^{+2.9}_{-3.9}$ rest-frame days. We combine our measurement with published CIV lags and derive the $r_{\rm BLR}-L$ relationship $\log_{10}( \tau / {\rm day}) = (1.00\pm 0.08) + (0.48\pm 0.04) \log_{10}[\lambda L_\lambda(1350{\r{A}})/10^{44}~{\rm erg ~s}^{-1}]$ with 0.32$\pm$0.06 dex intrinsic scatter. The velocity-resolved lags are consistent with circular Keplerian orbits, with $\tau_{\rm cen} = 86.2^{+4.5}_{-5.0}$, $25^{+11}_{-15}$, and $7.5^{+4.2}_{-3.5}$ rest-frame days for the core, blue wing, and red wing, respectively. Using $\sigma_{\rm line}$ with the mean spectrum and assuming $\log_{10} (f_{{\rm mean},\sigma}) = 0.52 \pm 0.26$, we derive $\log_{10}(M_{\rm BH}/M_{\odot}) = 8.63 \pm 0.27$. Given the quality of the data, this system represents a unique benchmark for calibration of $M_{\rm BH}$ estimators at high redshift. Future work will present dynamical modeling of the data to constrain the virial factor $f$ and $M_{\rm BH}$., Comment: 21 pages, 16 figures, 3 tables, submitted to ApJ

For the extremely bright lensed galaxy SDSS J1723+3411 at z=1.3293 , we analyze spatially integrated MMT, Keck, and Hubble Space Telescope spectra that fully cover the rest-frame wavelength range of 1400 to 7200 Angstroms. We also analyze near-IR spectra from Gemini that cover H alpha for a portion of the lensed arc. We report fluxes for 42 detected emission lines, and upper limits for an additional 22. This galaxy has extreme emission line ratios and high equivalent widths that are characteristic of extreme emission-line galaxies. We compute strong emission line diagnostics from both the rest-frame optical and rest-frame ultraviolet (UV), to constrain physical conditions and test the spectral diagnostics themselves. We tightly determine the nebular physical conditions using the most reliable diagnostics, and then compare to results from other diagnostics. We find disappointing performance from the UV--only diagnostics: they either are unable to measure the metallicity or dramatically under-estimate it; they over-estimate the pressure; and the UV diagnostic of ionization parameter has a strong metallicity dependence in this regime. Based on these results, we suggest that upcoming James Webb Space Telescope spectroscopic surveys of galaxies in the reionization epoch should invest the additional integration time to capture the optical [O II] and [O III] emission lines, and not rely solely on the rest-frame UV emission lines. We make available the spectra; they represent one of the highest-quality emission line spectral atlases of star-forming galaxy available beyond the local universe, and will aid planning observations with JWST., Comment: Accepted for publication in ApJ

In the era of large surveys, yielding thousands of galaxy clusters, efficient mass proxies at all scales are necessary in order to fully utilize clusters as cosmological probes. At the cores of strong lensing clusters, the Einstein radius can be turned into a mass estimate. This efficient method has been routinely used in literature, in lieu of detailed mass models; however, its scatter, assumed to be $\sim30\%$, has not yet been quantified. Here, we assess this method by testing it against ray-traced images of cluster-scale halos from the Outer Rim N-body cosmological simulation. We measure a scatter of $13.9\%$ and a positive bias of $8.8\%$ in $M(<\theta_E)$, with no systematic correlation with total cluster mass, concentration, or lens or source redshifts. We find that increased deviation from spherical symmetry increases the scatter; conversely, where the lens produces arcs that cover a large fraction of its Einstein circle, both the scatter and the bias decrease. While spectroscopic redshifts of the lensed sources are critical for accurate magnifications and time delays, we show that for the purpose of estimating the total enclosed mass, the scatter introduced by source redshift uncertainty is negligible compared to other sources of error. Finally, we derive and apply an empirical correction that eliminates the bias, and reduces the scatter to $10.1\%$ without introducing new correlations with mass, redshifts, or concentration. Our analysis provides the first quantitative assessment of the uncertainties in $M(<\theta_E)$, and enables its effective use as a core mass estimator of strong lensing galaxy clusters.

We present a novel Bayesian methodology to jointly model photometry and deep Hubble Space Telescope (HST) 2d grism spectroscopy of high-redshift galaxies. Our requiem2d code measures both unresolved and resolved stellar populations, ages, and star-formation histories (SFHs) for the ongoing REQIUEM (REsolving QUIEscent Magnified) Galaxies Survey, which targets strong gravitationally lensed quiescent galaxies at z~2. We test the accuracy of \texttt{requiem2d} using a simulated sample of massive galaxies at z~2 from the Illustris cosmological simulation and find we recover the general trends in SFH and median stellar ages. We further present a pilot study for the REQUIEM Galaxies Survey: MRG-S0851, a quintuply-imaged, massive ($\log M_* / M_\odot = 11.02 \pm 0.04$) red galaxy at $z=1.883\pm 0.001$. With an estimated gravitational magnification of $\mu = 5.7^{+0.4}_{-0.2}$, we sample the stellar populations on 0.6 kpc physical size bins. The global mass-weighted median age is constrained to be $1.8_{-0.2}^{+0.3}$ Gyr, and our spatially resolved analysis reveals that MRG-S0851 has a flat age gradient in the inner 3 kpc core after taking into account the subtle effects of dust and metallicity on age measurements, favoring an early formation scenario. The analysis for the full REQUIEM-2D sample will be presented in a forthcoming paper with a beta-release of the requiem2d code., Comment: 29 pages, 19 figures, accepted for publication in ApJ

WL measurements have well-known shear estimation biases, which can be partially corrected for with the use of image simulations. We present an analysis of simulated images that mimic HST/ACS observations of high-redshift galaxy clusters, including cluster specific issues such as non-weak shear and increased blending. Our synthetic galaxies have been generated to match the observed properties of the background-selected samples in the real images. First, we used simulations with galaxies on a grid to determine a revised signal-to-noise-dependent correction for multiplicative shear measurement bias, and to quantify the sensitivity of our bias calibration to mismatches of galaxy or PSF properties between the real data and the simulations. We studied the impact of increased blending and light contamination from cluster and foreground galaxies, finding it negligible for $z>0.7$ clusters, whereas there is an effect at the $\sim 1\%$ level for lower redshift clusters. Finally, we studied the impact of fainter neighbours and selection bias mimicking the positions and magnitudes of galaxies in CANDELS data. The initial SExtractor object detection causes a selection bias of $-0.028 \pm 0.002$, reduced to $-0.016 \pm 0.002$ by further cuts. We compared our CANDELS-based estimate to a grid-based analysis, with added clustered galaxies reaching even fainter magnitudes, yielding a refined estimate of $\sim -0.013$. Our pipeline is calibrated to an accuracy of $\sim 0.015$, which is fully sufficient for current and near-future weak lensing studies of high-redshift clusters. As an application, we used it for a refined analysis of three highly relaxed clusters from the SPT-SZ survey, including measurements down to $r>200$ kpc. Compared to previously employed scales, this tightens the cluster mass constraints by a factor 1.38 on average., Comment: 21 pages, 19 figures. Matches the version accepted for publication in A&A

For studies of galaxy formation and evolution, one of the major benefits of the James Webb Space Telescope is that space-based IFUs like those on its NIRSpec and MIRI instruments will enable spatially resolved spectroscopy of distant galaxies, including spectroscopy at the scale of individual star-forming regions in galaxies that have been gravitationally lensed. In the meantime, there is only a very small subset of lensed sources where work like this is possible even with the Hubble Space Telescope's Wide Field Camera 3 infrared channel grisms. We examine two of these sources, SDSS J1723+3411 and SDSS J2340+2947, using HST WFC3/IR grism data and supporting spatially-unresolved spectroscopy from several ground-based instruments to explore the size of spatial variations in observed strong emission line ratios like O32, R23, which are sensitive to ionization parameter and metallicity, and the Balmer decrement as an indicator of reddening. We find significant spatial variation in the reddening and the reddening-corrected O32 and R23 values which correspond to spreads of a few tenths of a dex in ionization parameter and metallicity. We also find clear evidence of a negative radial gradient in star formation in SDSS J2340+2947 and tentative evidence of one in SDSS J1723+3411, though its star formation is quite asymmetric. Finally, we find that reddening can vary enough spatially to make spatially-resolved reddening corrections necessary in order to characterize gradients in line ratios and the physical conditions inferred from them, necessitating the use of space-based IFUs for future work on larger, more statistically robust samples., Comment: 24 pages, including references, 6 tables, 17 figures, and appendix. Submitted to ApJ June 19, 2020

We present a three-dimensional kinematic reconstruction of the optically-emitting, oxygen-rich ejecta of supernova remnant N132D in the Large Magellanic Cloud. Data were obtained with the 6.5 m Magellan telescope in combination with the IMACS+GISMO instrument and survey [O III] $\lambda\lambda$4959,5007 line emission in a ${\sim}$3$^{\prime}~\times$ 3$^{\prime}$ region centered on N132D. The spatial and spectral resolution of our data enable detailed examination of the optical ejecta structure. The majority of N132D's optically bright oxygen ejecta are arranged in a torus-like geometry tilted approximately 28$^{\circ}$ with respect to the plane of the sky. The torus has a radius of 4.4 pc ($D_{\rm LMC}$/50 kpc), exhibits a blue-shifted radial velocity asymmetry of $-3000$ to $+2300$ km s$^{-1}$, and has a conspicuous break in its circumference. Assuming homologous expansion from the geometric center of O-rich filaments, the average expansion velocity of 1745 km s$^{-1}$ translates to an age since explosion of 2450 $\pm$ 195 yr. A faint, spatially-separated "runaway knot" (RK) with total space velocity of 3650 km s$^{-1}$ is nearly perpendicular to the torus plane and coincident with X-ray emission that is substantially enhanced in Si relative to the LMC and N132D's bulk ejecta. These kinematic and chemical signatures suggest that the RK may have had its origin deep within the progenitor star. Overall, the main shell morphology and high-velocity, Si-enriched components of N132D have remarkable similarity with that of Cassiopeia A, which was the result of a Type IIb supernova explosion. Our results underscore the need for further observations and simulations that can robustly reconcile whether the observed morphology is dominated by explosion dynamics or shaped by interaction with the environment., Comment: 18 pages, 12 figures, accepted for publication in ApJ; 3D animation of N132D can found at: http://www.physics.purdue.edu/kaboom/n132d-anim.mp4

We present spatially-resolved echelle spectroscopy of an intervening MgII-FeII-MgI absorption-line system detected at $z_{\rm abs}=0.73379$ toward the giant gravitational arc PSZ1 G311.65-18.48. The absorbing gas is associated to an inclined disk-like star-forming galaxy, whose major axis is aligned with the two arc-segments reported here. We probe in absorption the galaxy's extended disk continuously, at $\approx 3$ kpc sampling, from its inner region out to $15\times$ the optical radius. We detect strong ($W_0^{2796}>0.3$ \r{A}) coherent absorption along $13$ independent positions at impact parameters $D=0$--$29$ kpc on one side of the galaxy, and no absorption at $D=28$--$57$ kpc on the opposite side (all de-lensed distances at $z_{\rm abs}$). We show that: (1) the gas distribution is anisotropic; (2) $W_0^{2796}$, $W_0^{2600}$, $W_0^{2852}$, and the ratio $W_0^{2600}\!/W_0^{2796}$, all anti-correlate with $D$; (3) the $W_0^{2796}$-$D$ relation is not cuspy and exhibits significantly less scatter than the quasar-absorber statistics; (4) the absorbing gas is co-rotating with the galaxy out to $D \lesssim 20$ kpc, resembling a `flat' rotation curve, but at $D\gtrsim 20$ kpc velocities decline below the expectations from a 3D disk-model extrapolated from the nebular [OII] emission. These signatures constitute unambiguous evidence for rotating extra-planar diffuse gas, possibly also undergoing enriched accretion at its edge. Arguably, we are witnessing some of the long-sought processes of the baryon cycle in a single distant galaxy expected to be representative of such phenomena., Comment: Accepted for publication in MNRAS

We present an analysis of the mass distribution inferred from strong lensing by SPT-CL J0356-5337, a cluster of galaxies at redshift z = 1.0359 revealed in the follow-up of the SPT-SZ clusters. The cluster has an Einstein radius of Erad=14 for a source at z = 3 and a mass within 500 kpc of M_500kpc = 4.0+-0.8x10^14Msol. Our spectroscopic identification of three multiply-imaged systems (z = 2.363, z = 2.364, and z = 3.048), combined with HST F606W-band imaging allows us to build a strong lensing model for this cluster with an rms of <0.3'' between the predicted and measured positions of the multiple images. Our modeling reveals a two-component mass distribution in the cluster. One mass component is dominated by the brightest cluster galaxy and the other component, separated by ~170 kpc, contains a group of eight red elliptical galaxies confined in a ~9'' (~70 kpc) diameter circle. We estimate the mass ratio between the two components to be between 1:1.25 and 1:1.58. In addition, spectroscopic data reveal that these two near-equal mass cores have only a small velocity difference of 300 km/s between the two components. This small radial velocity difference suggests that most of the relative velocity takes place in the plane of the sky, and implies that SPT-CL J0356-5337 is a major merger with a small impact parameter seen face-on. We also assess the relative contributions of galaxy-scale halos to the overall mass of the core of the cluster and find that within 800 kpc from the brightest cluster galaxy about 27% of the total mass can be attributed to visible and dark matter associated with galaxies, whereas only 73% of the total mass in the core comes from cluster-scale dark matter halos., Comment: 19 pages, 11 figures. Submitted to ApJ

In the past decade, our understanding of how stars and galaxies formed during the first 5 billion years after the Big Bang has been revolutionized by observations that leverage gravitational lensing by intervening masses, which act as natural cosmic telescopes to magnify background sources. Previous studies have harnessed this effect to probe the distant universe at ultraviolet, optical, infrared and millimeter wavelengths. However, strong lensing studies of young, star-forming galaxies have never extended into X-ray wavelengths, which uniquely trace high-energy phenomena. Here we report an X-ray detection of star formation in a highly magnified, strongly lensed galaxy. This lensed galaxy, seen during the first third of the history of the Universe, is a low--mass, low--metallicity starburst with elevated X-ray emission, and is a likely analog to the first generation of galaxies. Our measurements yield insight into the role that X-ray emission from stellar populations in the first generation of galaxies may play in re-ionizing the Universe. This observation paves the way for future strong lensing-assisted X-ray studies of distant galaxies reaching orders of magnitude below the detection limits of current deep fields, and previews the depths that will be attainable with future X-ray observatories., Comment: Published in Nature Astronomy

We describe the observations and resultant galaxy cluster catalog from the 2770 deg$^2$ SPTpol Extended Cluster Survey (SPT-ECS). Clusters are identified via the Sunyaev-Zel'dovich (SZ) effect, and confirmed with a combination of archival and targeted follow-up data, making particular use of data from the Dark Energy Survey (DES). With incomplete followup we have confirmed as clusters 244 of 266 candidates at a detection significance $\xi \ge 5$ and an additional 204 systems at $4<\xi<5$. The confirmed sample has a median mass of $M_{500c} \sim {4.4 \times 10^{14} M_\odot h_{70}^{-1}}$, a median redshift of $z=0.49$, and we have identified 44 strong gravitational lenses in the sample thus far. Radio data are used to characterize contamination to the SZ signal; the median contamination for confirmed clusters is predicted to be $\sim$1% of the SZ signal at the $\xi>4$ threshold, and $<4\%$ of clusters have a predicted contamination $>10\% $ of their measured SZ flux. We associate SZ-selected clusters, from both SPT-ECS and the SPT-SZ survey, with clusters from the DES redMaPPer sample, and find an offset distribution between the SZ center and central galaxy in general agreement with previous work, though with a larger fraction of clusters with significant offsets. Adopting a fixed Planck-like cosmology, we measure the optical richness-to-SZ-mass ($\lambda-M$) relation and find it to be 28% shallower than that from a weak-lensing analysis of the DES data---a difference significant at the 4 $\sigma$ level---with the relations intersecting at $\lambda=60$ . The SPT-ECS cluster sample will be particularly useful for studying the evolution of massive clusters and, in combination with DES lensing observations and the SPT-SZ cluster sample, will be an important component of future cosmological analyses., Comment: 49 pages, 14 figures, 10 tables. Minor changes to match accepted version in ApJS

We present a catalog of galaxy cluster candidates detected in 100 square degrees surveyed with the SPTpol receiver on the South Pole Telescope. The catalog contains 89 candidates detected with a signal-to-noise ratio greater than 4.6. The candidates are selected using the Sunyaev-Zel'dovich effect at 95 and 150 GHz. Using both space- and ground-based optical and infrared telescopes, we have confirmed 81 candidates as galaxy clusters. We use these follow-up images and archival images to estimate photometric redshifts for 66 galaxy clusters and spectroscopic observations to obtain redshifts for 13 systems. An additional 2 galaxy clusters are confirmed using the overdensity of near-infrared galaxies only, and are presented without redshifts. We find that 15 candidates (18% of the total sample) are at redshift of $z \geq 1.0$, with a maximum confirmed redshift of $z_{\rm{max}} = 1.38 \pm 0.10$. We expect this catalog to contain every galaxy cluster with $M_{500c} > 2.6 \times 10^{14} M_\odot h^{-1}_{70}$ and $z > 0.25$ in the survey area. The mass threshold is approximately constant above $z = 0.25$, and the complete catalog has a median mass of approximately $ M_{500c} = 2.7 \times 10^{14} M_\odot h^{-1}_{70}$. Compared to previous SPT works, the increased depth of the millimeter-wave data (11.2 and 6.5 $\mu$K-arcmin at 95 and 150 GHz, respectively) makes it possible to find more galaxy clusters at high redshift and lower mass., Comment: 21 pages, 7 figures, associated data available at http://pole.uchicago.edu/public/data/sptsz-clusters. V2 was accepted to the AJ, and includes minor changes requested by the reviewer

The ionizing photons produced by massive stars are key actors in galaxy evolution. Ionizing photon production and escape is poorly understood. Improved space-based, spatially-resolved, multiplexed spectroscopic capabilities covering observed wavelengths of 1000 to 3000 Angstrom, in concert with spectroscopy from the ELTs and JWST, would lead to definitive answers as to how ionizing photons are produced and leaked, what populations of galaxies are responsible for ionizing photon leakage, what determines whether escape is possible, and how ionizing galaxy populations evolve over cosmic time., Comment: Science White Paper submitted to the Astro2020 Decadal Survey. 5 pages plus references and cover page

We infer the properties of massive star populations using the far-ultraviolet stellar continua of 61 star-forming galaxies: 42 at low-z observed with HST and 19 at z~2 from the Megasaura sample. We fit each stellar continuum with a linear combination of up to 50 single age and single metallicity Starburst99 models. From these fits, we derive light-weighted ages and metallicities, which agree with stellar wind and photospheric spectral features, and infer the spectral shapes and strengths of the ionizing continua. Inferred light-weighted stellar metallicities span 0.05-1.5 Z$_\odot$ and are similar to the measured nebular metallicities. We quantify the ionizing continua using the ratio of the ionizing flux at 900\AA\ to the non-ionizing flux at 1500\AA\ and demonstrate the evolution of this ratio with stellar age and metallicity using theoretical single burst models. These single burst models only match the inferred ionizing continua of half of the sample, while the other half are described by a mixture of stellar ages. Mixed age populations produce stronger and harder ionizing spectra than continuous star formation histories, but, contrary to previous studies that assume constant star formation, have similar stellar and nebular metallicities. Stellar population age and metallicity affect the far-UV continua in different and distinguishable ways; assuming a constant star formation history diminishes the diagnostic power. Finally, we provide simple prescriptions to determine the ionizing photon production efficiency ($\xi_{ion}$) from the stellar population properties. $\xi_{ion}$ has a range of log($\xi_{ion})=24.4-25.7$ Hz erg$^{-1}$ that depends on stellar age, metallicity, star formation history, and contributions from binary star evolution. These stellar population properties must be observationally determined to determine the number of ionizing photons generated by massive stars., Comment: 31 pages, 23 figures, resubmitted to ApJ after incorporating the referee's comments. Comments encouraged