RELICS: High-Resolution Constraints on the Inner Mass Distribution of the z=0.83 Merging Cluster RXJ0152.7-1357 from strong lensing

Strong gravitational lensing (SL) is a powerful means to map the distribution of dark matter. In this work, we perform a SL analysis of the prominent X-ray cluster RXJ0152.7-1357 (z=0.83, also known as CL 0152.7-1357) in \textit{Hubble Space Telescope} images, taken in the framework of the Reionization Lensing Cluster Survey (RELICS). On top of a previously known $z=3.93$ galaxy multiply imaged by RXJ0152.7-1357, for which we identify an additional multiple image, guided by a light-traces-mass approach we identify seven new sets of multiply imaged background sources lensed by this cluster, spanning the redshift range [1.79-3.93]. A total of 25 multiple images are seen over a small area of ~0.4 $arcmin^2$, allowing us to put relatively high-resolution constraints on the inner matter distribution. Although modestly massive, the high degree of substructure together with its very elongated shape make RXJ0152.7-1357 a very efficient lens for its size. This cluster also comprises the third-largest sample of z~6-7 candidates in the RELICS survey. Finally, we present a comparison of our resulting mass distribution and magnification estimates with those from a Lenstool model. These models are made publicly available through the MAST archive.Comment: 15 Pages, 7 Figures, 4 Tables Accepted for publication in Ap

Keck-I MOSFIRE Spectroscopy of Compact Star-Forming Galaxies at \u3cem\u3ez\u3c/em\u3e ≳ 2: High Velocity Dispersions in Progenitors of Compact Quiescent Galaxies

We present Keck-I MOSFIRE near-infrared spectroscopy for a sample of 13 compact star-forming galaxies (SFGs) at redshift 2 ≤ z ≤ 2.5 with star formation rates of SFR ~ 100 M ☉ yr–1 and masses of log(M/M ☉) ~10.8. . . . For the remainder of the abstract, please visit: http://dx.doi.org/10.1088/0004-637X/795/2/14

The Evolution of the Galaxy Rest-Frame Ultraviolet Luminosity Function Over the First Two Billion Years

We present a robust measurement and analysis of the rest-frame ultraviolet (UV) luminosity function at z=4-8. We use deep Hubble Space Telescope imaging over the CANDELS/GOODS fields, the Hubble Ultra Deep Field and the Year 1 Hubble Frontier Field deep parallel observations. These surveys provides an effective volume of 0.6-1.2 x 10^6 Mpc^3 over this epoch, allowing us to perform a robust search for faint (M_UV=-18) and bright (M_UV < -21) galaxies. We select candidate galaxies using a well-tested photometric redshift technique with careful screening of contaminants, finding a sample of 7446 galaxies at 3.51000 galaxies at z~6-8. We measure the luminosity function using a Markov Chain Monte Carlo analysis to measure robust uncertainties. At the faint end our results agree with previous studies, yet we find a higher abundance of UV-bright galaxies at z>6, with M* ~ -21 at z>5, different than that inferred based on previous trends at lower redshift. At z=8, a single power-law provides an equally good fit to the UV luminosity function, while at z=6 and 7, an exponential cutoff at the bright-end is moderately preferred. We compare to semi-analytical models, and find that the lack of evolution in M* is consistent with models where the impact of dust attenuation on the bright-end of the luminosity function decreases at higher redshift. We measure the evolution of the cosmic star-formation rate density, correcting for dust attenuation, and find that it declines as (1+z)^(-4.3 +/- 0.5) at z>4, consistent with observations at z>9. Our observations are consistent with a reionization history that starts at z>10, completes at z>6, and reaches a midpoint (x_HII = 0.5) at 6.7<z<9.4. Finally, our observations predict that the abundance of bright z=9 galaxies is likely higher than previous constraints, though consistent with recent estimates of bright z~10 galaxies. [abridged]Comment: Re-submitted to the Astrophysical Journal after first referee's report. 34 pages, 21 figures, 7 tables. The source file includes a machine readable table of our full galaxy sampl

RELICS: Strong Lensing analysis of the galaxy clusters Abell S295, Abell 697, MACS J0025.4-1222, and MACS J0159.8-0849

We present a strong-lensing analysis of four massive galaxy clusters imaged with the Hubble Space Telescope in the Reionization Lensing Cluster Survey. We use a Light-Traces-Mass technique to uncover sets of multiply images and constrain the mass distribution of the clusters. These mass models are the first published for Abell S295 and MACS J0159.8-0849, and are improvements over previous models for Abell 697 and MACS J0025.4-1222. Our analysis for MACS J0025.4-1222 and Abell S295 shows a bimodal mass distribution supporting the merger scenarios proposed for these clusters. The updated model for MACS J0025.4-1222 suggests a substantially smaller critical area than previously estimated. For MACS J0159.8-0849 and Abell 697 we find a single peak and relatively regular morphology, revealing fairly relaxed clusters. Despite being less prominent lenses, three of these clusters seem to have lensing strengths, i.e. cumulative area above certain magnification, similar to the Hubble Frontier Fields clusters (e.g., A($\mu>5$) $\sim 1-3$ arcmin$^2$, A($\mu>10$) $\sim 0.5-1.5$ arcmin$^2$), which in part can be attributed to their merging configurations. We make our lens models publicly available through the Mikulski Archive for Space Telescopes. Finally, using Gemini-N/GMOS spectroscopic observations we detect a single emission line from a high-redshift $J_{125}\simeq25.7$ galaxy candidate lensed by Abell 697. While we cannot rule out a lower-redshift solution, we interpret the line as Ly$\alpha$ at $z=5.800\pm 0.001$, in agreement with its photometric redshift and dropout nature. Within this scenario we measure a Ly$\alpha$ rest-frame equivalent width of $52\pm22$ \AA, and an observed Gaussian width of $117\pm 15$ km/s.Comment: 23 pages, 16 figures; V2, accepted for publication in Ap

RELICS: Reionization Lensing Cluster Survey

Large surveys of galaxy clusters with the Hubble and Spitzer Space Telescopes, including CLASH and the Frontier Fields, have demonstrated the power of strong gravitational lensing to efficiently deliver large samples of high-redshift galaxies. We extend this strategy through a wider, shallower survey named RELICS, the Reionization Lensing Cluster Survey. This survey, described here, was designed primarily to deliver the best and brightest high-redshift candidates from the first billion years after the Big Bang. RELICS observed 41 massive galaxy clusters with Hubble and Spitzer at 0.4-1.7um and 3.0-5.0um, respectively. We selected 21 clusters based on Planck PSZ2 mass estimates and the other 20 based on observed or inferred lensing strength. Our 188-orbit Hubble Treasury Program obtained the first high-resolution near-infrared images of these clusters to efficiently search for lensed high-redshift galaxies. We observed 46 WFC3/IR pointings (~200 arcmin^2) with two orbits divided among four filters (F105W, F125W, F140W, and F160W) and ACS imaging as needed to achieve single-orbit depth in each of three filters (F435W, F606W, and F814W). As previously reported by Salmon et al., we discovered 322 z ~ 6 - 10 candidates, including the brightest known at z ~ 6, and the most distant spatially-resolved lensed arc known at z ~ 10. Spitzer IRAC imaging (945 hours awarded, plus 100 archival) has crucially enabled us to distinguish z ~ 10 candidates from z ~ 2 interlopers. For each cluster, two HST observing epochs were staggered by about a month, enabling us to discover 11 supernovae, including 3 lensed supernovae, which we followed up with 20 orbits from our program. We delivered reduced HST images and catalogs of all clusters to the public via MAST and reduced Spitzer images via IRSA. We have also begun delivering lens models of all clusters, to be completed before the JWST GO call for proposals.Comment: 29 pages, 6 figures, submitted to ApJ. For reduced images, catalogs, lens models, and more, see relics.stsci.ed

Occurrence of Carbapenem-Resistant Acinetobacter baumannii Clones at Multiple Hospitals in London and Southeast England

From late 2003 to the end of 2005, the Health Protection Agency's national reference laboratories received approximately 1,600 referrals of Acinetobacter spp., including 419 and 58 examples, respectively, of two carbapenem-resistant Acinetobacter baumannii lineages, designated OXA-23 clones 1 and 2. Representatives of these clones were obtained from 40 and 8 hospitals, respectively, in London or elsewhere in Southeast England. Both clones had blaOXA-23-like genes, as well as the intrinsic (but downregulated) blaOXA-51-like carbapenemase genes typical of A. baumannii. Both were highly multiresistant: only colistin and tigecycline remained active versus OXA-23 clone 1 isolates; OXA-23 clone 2 isolates were also susceptible to amikacin and minocycline. These lineages increase the burden created by the southeast (SE) clone, a previously reported A. baumannii lineage with variable carbapenem resistance contingent on upregulation of the blaOXA-51-like gene. Known since 2000, the SE clone had been referred from over 40 hospitals by the end of 2005, with 627 representatives received by the reference laboratories. The OXA-23 clone 2 is now in decline, but OXA-23 clone 1 continues to be referred from new sites, as does the SE clone. Their spread is forcing the use of unorthodox therapies, principally colistin and tigecycline, although the optimal regimens remain uncertain

Antimicrobial treatment and clinical outcome for infections with carbapenem- and multiply-resistant <i>Acinetobacter baumannii</i> around London

Carbapenem- and multiply-resistant Acinetobacter baumannii (C-MRAB) are challenging pathogens, often susceptible only to polymyxins and tigecycline. We reviewed clinical outcomes in relation to antibiotic treatment for 166 consecutive patients infected or colonised with these organisms at 18 hospitals around London, UK. Clinical data were obtained along with the isolates, which were typed by pulsed-field gel electrophoresis (PFGE). Outcomes were compared for colonised and infected patients and in relation to treatment, with associations examined by logistic regression. Most subjects (103/166; 62%) were in Intensive Care Units (ICUs) or high dependency units; 84 (50.6%) were judged to be infected and 73 (44.0%) were colonised, with 9 indeterminate. Among the 166 C-MRAB isolates, 141 belonged to OXA-23 clone 1, a European clone II lineage. Survival rates among infected and colonised patients were 68% and 67%, respectively (P &gt; 0.05), indicating little attributable mortality. Univariate and multivariate analyses indicated poorer outcomes among ICU-infected patients and those with pulmonary infection or bacteraemia, whereas trauma patients had significantly better outcomes than the generality. Outcomes varied with hospital, even in multivariate analysis, reflecting either differences in management or case mix. There was little association between outcome and therapy with colistin and/or tigecycline except that, among patients with respiratory infection, 12/15 treated with intravenous colistin alone had poor outcome compared with 1/8 whose therapy include nebulised colistin. This difference was significant (P = 0.003), although the patients receiving nebulised drug were mostly younger, included trauma cases and were at a hospital with good outcomes

Antimicrobial treatment and clinical outcome for infections with carbapenem- and multiply-resistant Acinetobacter baumannii around London

Carbapenem- and multiply-resistant Acinetobacter baumannii (C-MRAB) are challenging pathogens, often susceptible only to polymyxins and tigecycline. We reviewed clinical outcomes in relation to antibiotic treatment for 166 consecutive patients infected or colonised with these organisms at 18 hospitals around London, UK. Clinical data were obtained along with the isolates, which were typed by pulsed-field gel electrophoresis (PFGE). Outcomes were compared for colonised and infected patients and in relation to treatment, with associations examined by logistic regression. Most subjects (103/166; 62%) were in Intensive Care Units (ICUs) or high dependency units; 84 (50.6%) were judged to be infected and 73 (44.0%) were colonised, with 9 indeterminate. Among the 166 C-MRAB isolates, 141 belonged to OXA-23 clone 1, a European clone II lineage. Survival rates among infected and colonised patients were 68% and 67%, respectively (P > 0.05), indicating little attributable mortality. Univariate and multivariate analyses indicated poorer outcomes among ICU-infected patients and those with pulmonary infection or bacteraemia, whereas trauma patients had significantly better outcomes than the generality. Outcomes varied with hospital, even in multivariate analysis, reflecting either differences in management or case mix. There was little association between outcome and therapy with colistin and/or tigecycline except that, among patients with respiratory infection, 12/15 treated with intravenous colistin alone had poor outcome compared with 1/8 whose therapy include nebulised colistin. This difference was significant (P = 0.003), although the patients receiving nebulised drug were mostly younger, included trauma cases and were at a hospital with good outcomes