Showing papers by "Tommaso Treu published in 2018"
TL;DR: In this paper, a new flexible Bayesian framework was proposed for directly inferring the fraction of neutral hydrogen in the intergalactic medium (IGM) during the Epoch of Reionization (EoR, z~6-10) from detections and non-detections of Lyman Alpha (Ly$\\alpha$) emission from Lyman break galaxies (LBGs).
Abstract: We present a new flexible Bayesian framework for directly inferring the fraction of neutral hydrogen in the intergalactic medium (IGM) during the Epoch of Reionization (EoR, z~6-10) from detections and non-detections of Lyman Alpha (Ly$\\alpha$) emission from Lyman break galaxies (LBGs). Our framework combines sophisticated reionization simulations with empirical models of the interstellar medium (ISM) radiative transfer effects on Ly$\\alpha$. We assert that the Ly$\\alpha$ line profile emerging from the ISM has an important impact on the resulting transmission of photons through the IGM, and that these line profiles depend on galaxy properties. We model this effect by considering the peak velocity offset of Ly$\\alpha$ lines from host galaxies' systemic redshifts, which are empirically correlated with UV luminosity and redshift (or halo mass at fixed redshift). We use our framework on the sample of LBGs presented in Pentericci et al. (2014) and infer a global neutral fraction at z~7 of $\\overline{x}_\\mathrm{HI} = 0.59_{-0.15}^{+0.11}$, consistent with other robust probes of the EoR and confirming reionization is on-going ~700 Myr after the Big Bang. We show that using the full distribution of Ly$\\alpha$ equivalent width detections and upper limits from LBGs places tighter constraints on the evolving IGM than the standard Ly$\\alpha$ emitter fraction, and that larger samples are within reach of deep spectroscopic surveys of gravitationally lensed fields and JWST NIRSpec.
158 citations
University of California, Berkeley1, University of Minnesota2, Spanish National Research Council3, University of South Carolina4, University of Hawaii5, Ikerbasque6, University of the Basque Country7, Ben-Gurion University of the Negev8, University of California, Los Angeles9, Complutense University of Madrid10, Tohoku University11, University of KwaZulu-Natal12, Durham University13, University of Copenhagen14, Institute for the Physics and Mathematics of the Universe15, University of Tokyo16, Space Telescope Science Institute17, University of Arizona18, University of Maryland, College Park19, Goddard Space Flight Center20, University of California, Santa Barbara21, Las Cumbres Observatory Global Telescope Network22, École normale supérieure de Lyon23, Rutgers University24, University of California, Santa Cruz25, Johns Hopkins University26, University of California, Davis27, University of São Paulo28, University of Geneva29, University of Amsterdam30, American Museum of Natural History31, Harvard University32, University of Milan33, École Polytechnique Fédérale de Lausanne34, INAF35, University of La Laguna36, University of Ferrara37, Leibniz Institute for Astrophysics Potsdam38, University of Michigan39
TL;DR: In this article, an image of an individual star at redshift z = 1.49 (dubbed MACS J1149 Lensed Star 1) magnified by more than 2,000 Gaussians was reported.
Abstract: Galaxy-cluster gravitational lenses can magnify background galaxies by a total factor of up to ~50. Here we report an image of an individual star at redshift z = 1.49 (dubbed MACS J1149 Lensed Star 1) magnified by more than ×2,000. A separate image, detected briefly 0.26″ from Lensed Star 1, is probably a counterimage of the first star demagnified for multiple years by an object of ≳3 solar masses in the cluster. For reasonable assumptions about the lensing system, microlensing fluctuations in the stars’ light curves can yield evidence about the mass function of intracluster stars and compact objects, including binary fractions and specific stellar evolution and supernova models. Dark-matter subhaloes or massive compact objects may help to account for the two images’ long-term brightness ratio.
115 citations
École Polytechnique Fédérale de Lausanne1, Fermilab2, University of California, Davis3, University of Chicago4, Stanford University5, Max Planck Society6, University of California, Los Angeles7, Andrés Bello National University8, Millennium Institute9, Valparaiso University10, European Southern Observatory11, University of Cambridge12, University College London13, Institut d'Astrophysique de Paris14, SLAC National Accelerator Laboratory15, National Center for Supercomputing Applications16, University of Illinois at Urbana–Champaign17, IFAE18, University of Pennsylvania19, Texas A&M University20, Indian Institute of Technology, Hyderabad21, Institut de Ciències de l'Espai22, Autonomous University of Madrid23, University of California, Berkeley24, Lawrence Berkeley National Laboratory25, Ohio State University26, University of Washington27, Australian Astronomical Observatory28, Argonne National Laboratory29, University of São Paulo30, Catalan Institution for Research and Advanced Studies31, California Institute of Technology32, University of Michigan33, University of Southampton34, State University of Campinas35, Oak Ridge National Laboratory36
TL;DR: The DES data management system is supported by the National Science Foundation under Grant Number AST-1138766 as mentioned in this paper, and the DES participants from Spanish institutions are partially supported by MINECO under grants AYA2015-71825, ESP2015-88861, FPA2015-68048, SEV-2012-0234, SEVERO-0249, and MDM-2015-0509, some of which include ERDF funds from the European Union.
Abstract: This work is supported by the Swiss National Science Foundation (SNSF). S. H. Suyu and D. C. Y. Chao thank the Max Planck Society for support through the Max Planck Research Group for SHS. T. Treu acknowledges support by the National Science Foundation through grant 1450141, by the Packard Foundation through a Packard Research Fellowship and by the UCLA Dean of Physical Sciences. K. Rojas is supported by Becas de Doctorado Nacional CONICYT 2017. T. Anguita and M. Chijani acknowledge support by proyecto FONDECYT 11130630 and by the Ministry for the Economy, Development, and Tourism’s Programa Inicativa Cientifica Milenio through grant IC 12009, awarded to The Millennium Institute of Astrophysics (MAS). M. Tewes acknowledges support from the DFG grant Hi 1495/2-1. J. Garcia-Bellido is supported by the Research Project FPA2015-68048 [MINECO-FEDER], and the Centro de Excelencia Severo Ochoa Program SEV-2012-0249. C. D. Fassnacht acknowledges support from the National Science Foundation grant AST-1312329 and from the UC Davis Physics Department and Dean of Math and Physical Sciences. Funding for the DES Projects has been provided by the US Department of Energy, the US National Science Foundation, the Ministry of Science and Education of Spain, the Science and Technology Facilities Council of the United Kingdom, the Higher Education Funding Council for England, the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign, the Kavli Institute of Cosmological Physics at the University of Chicago, the Center for Cosmology and Astro-Particle Physics at the Ohio State University, the Mitchell Institute for Fundamental Physics and Astronomy at Texas A&M University, Financiadora de Estudos e Projetos, Fundacao Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro, Conselho Nacional de Desenvolvimento Cientifico e Tecnologico and the Ministerio da Ciencia, Tecnologia e Inovacao, the Deutsche Forschungsgemeinschaft and the Collaborating Institutions in the Dark Energy Survey ... The DES data management system is supported by the National Science Foundation under Grant Number AST-1138766. The DES participants from Spanish institutions are partially supported by MINECO under grants AYA2015-71825, ESP2015-88861, FPA2015-68048, SEV-2012-0234, SEV-2012-0249, and MDM-2015-0509, some of which include ERDF funds from the European Union. IFAE is partially funded by the CERCA programme of the Generalitat de Catalunya.
101 citations
University of Edinburgh1, INAF2, Centre national de la recherche scientifique3, Max Planck Society4, University of Cambridge5, European Southern Observatory6, University of Geneva7, University of Texas at Austin8, Diego Portales University9, University College London10, University of Oxford11, Kapteyn Astronomical Institute12, University of Nottingham13, Ludwig Maximilian University of Munich14, University of Michigan15, University of Lisbon16, Valparaiso University17, Pierre-and-Marie-Curie University18, University of Bologna19, Harvard University20, Space Telescope Science Institute21, University of Copenhagen22, Imperial College London23, University of Massachusetts Amherst24, Pontifical Catholic University of Chile25, Aix-Marseille University26, University of La Laguna27, Texas A&M University28, Durham University29, Leiden University30, University of Arizona31, University of St Andrews32
TL;DR: The VANDELS survey as mentioned in this paper was designed to support the science exploitation of the first ESO public data release, focusing on the scientific motivation, survey design, and target selection.
Abstract: VANDELS is a uniquely deep spectroscopic survey of high-redshift galaxies with the VIMOS spectrograph on ESO’s Very Large Telescope (VLT). The survey has obtained ultradeep optical (0.48 < λ < 1.0 μm) spectroscopy of ≃2100 galaxies within the redshift interval 1.0 ≤ z ≤ 7.0, over a total area of ≃0.2 deg2 centred on the CANDELS Ultra Deep Survey and Chandra Deep Field South fields. Based on accurate photometric redshift pre-selection, 85 per cent of the galaxies targeted by VANDELS were selected to be at z ≥ 3. Exploiting the red sensitivity of the refurbished VIMOS spectrograph, the fundamental aim of the survey is to provide the high-signal-to-noise ratio spectra necessary to measure key physical properties such as stellar population ages, masses, metallicities, and outflow velocities from detailed absorption-line studies. Using integration times calculated to produce an approximately constant signal-to-noise ratio (20 < tint< 80 h), the VANDELS survey targeted: (a) bright star-forming galaxies at 2.4 ≤ z ≤ 5.5, (b) massive quiescent galaxies at 1.0 ≤ z ≤ 2.5, (c) fainter star-forming galaxies at 3.0 ≤ z ≤ 7.0, and (d) X-ray/Spitzer-selected active galactic nuclei and Herschel-detected galaxies. By targeting two extragalactic survey fields with superb multiwavelength imaging data, VANDELS will produce a unique legacy data set for exploring the physics underpinning high-redshift galaxy evolution. In this paper, we provide an overview of the VANDELS survey designed to support the science exploitation of the first ESO public data release, focusing on the scientific motivation, survey design, and target selection.
97 citations
TL;DR: The first data release (DR1) of the ESO public spectroscopic survey "VANDELS, a deep VIMOS survey of the CANDELS CDFS and UDS fields" is described in this article.
Abstract: This paper describes the observations and the first data release (DR1) of the ESO public spectroscopic survey "VANDELS, a deep VIMOS survey of the CANDELS CDFS and UDS fields". VANDELS' main targets are star-forming galaxies at 2.4
84 citations
INAF1, University of Edinburgh2, University of Cambridge3, European Southern Observatory4, University of Geneva5, Centre national de la recherche scientifique6, University of Texas at Austin7, Diego Portales University8, University College London9, University of Oxford10, Kapteyn Astronomical Institute11, Max Planck Society12, University of Nottingham13, Ludwig Maximilian University of Munich14, University of Michigan15, University of Lisbon16, Valparaiso University17, Pierre-and-Marie-Curie University18, Harvard University19, Space Telescope Science Institute20, University of Copenhagen21, University of Massachusetts Amherst22, Pontifical Catholic University of Chile23, Aix-Marseille University24, Spanish National Research Council25, University of La Laguna26, Texas A&M University27, Durham University28, Leiden University29, University of Arizona30, University of St Andrews31
TL;DR: The first data release (DR1) of the ESO public spectroscopic survey “VANDELS, a deep VIMOS survey of the CANDELS CDFS and UDS fields is described in this paper.
Abstract: This paper describes the observations and the first data release (DR1) of the ESO public spectroscopic survey “VANDELS, a deep VIMOS survey of the CANDELS CDFS and UDS fields”. The main targets of VANDELS are star-forming galaxies at redshift 2.4 < z < 5.5, an epoch when the Universe had not yet reached 20% of its current age, and massive passive galaxies in the range 1 < z < 2.5. By adopting a strategy of ultra-long exposure times, ranging from a minimum of 20 h to a maximum of 80 h per source, VANDELS is specifically designed to be the deepest-ever spectroscopic survey of the high-redshift Universe. Exploiting the red sensitivity of the refurbished VIMOS spectrograph, the survey is obtaining ultra-deep optical spectroscopy covering the wavelength range 4800–10 000 Å with a sufficiently high signal-to-noise ratio to investigate the astrophysics of high-redshift galaxy evolution via detailed absorption line studies of well-defined samples of high-redshift galaxies. VANDELS-DR1 is the release of all medium-resolution spectroscopic data obtained during the first season of observations, on a 0.2 square degree area centered around the CANDELS-CDFS (Chandra deep-field south) and CANDELS-UDS (ultra-deep survey) areas. It includes data for all galaxies for which the total (or half of the total) scheduled integration time was completed. The DR1 contains 879 individual objects, approximately half in each of the two fields, that have a measured redshift, with the highest reliable redshifts reaching zspec ~ 6. In DR1 we include fully wavelength-calibrated and flux-calibrated 1D spectra, the associated error spectrum and sky spectrum, and the associated wavelength-calibrated 2D spectra. We also provide a catalog with the essential galaxy parameters, including spectroscopic redshifts and redshift quality flags measured by the collaboration. We present the survey layout and observations, the data reduction and redshift measurement procedure, and the general properties of the VANDELS-DR1 sample. In particular, we discuss the spectroscopic redshift distribution and the accuracy of the photometricredshifts for each individual target category, and we provide some examples of data products for the various target typesand the different quality flags. All VANDELS-DR1 data are publicly available and can be retrieved from the ESO archive. Two further data releases are foreseen in the next two years, and a final data release is currently scheduled for June 2020, which will include an improved rereduction of the entire spectroscopic data set.
83 citations
University of Copenhagen1, University of Milan2, University of Ferrara3, INAF4, Max Planck Society5, Academia Sinica6, Technische Universität München7, Ludwig Maximilian University of Munich8, Kapteyn Astronomical Institute9, University of California, Berkeley10, University of South Carolina11, University of California, Los Angeles12
TL;DR: In this paper, the authors used the observed positions of 89 multiple images, with extensive spectroscopic information, from 28 background sources and the measured time delays between the images S1-S4 and SX of supernova "Refsdal" (z = 1.489), which were obtained thanks to Hubble Space Telescope deep imaging and Multi Unit Spectroscopic Explorer data.
Abstract: Realizing Refsdal's original idea from 1964, we present estimates of the Hubble constant that are complementary to, and potentially competitive with, those of other cosmological probes. We use the observed positions of 89 multiple images, with extensive spectroscopic information, from 28 background sources and the measured time delays between the images S1-S4 and SX of supernova "Refsdal" (z = 1.489), which were obtained thanks to Hubble Space Telescope deep imaging and Multi Unit Spectroscopic Explorer data. We extend the strong-lensing modeling of the Hubble Frontier Fields galaxy cluster MACS J1149.5+2223 (z = 0.542), published by Grillo et al. (2016), and explore different Lambda CDM models. Taking advantage of the lensing information associated to the presence of very close pairs of multiple images at various redshifts, and to the extended surface brightness distribution of the SN Refsdal host, we can reconstruct the total mass-density profile of the cluster very precisely. The combined dependence of the multiple-image positions and time delays on the cosmological parameters allows us to infer the values of H-0 and Omega(m) with relative (1 sigma) statistical errors of, respectively, 6% (7%) and 31% (26%) in flat (general) cosmological models, assuming a conservative 3% uncertainty on the final time delay of image SX and, remarkably, no priors from other cosmological experiments. Our best estimate of H-0, based on the model described in this work, will be presented when the final time-delay measurement becomes available. Our results show that it is possible to utilize time delays in lens galaxy clusters as an important alternative tool for measuring the expansion rate and the geometry of the universe.
80 citations
University of California, Los Angeles1, Harvard University2, University of Auckland3, University of California, Irvine4, California Polytechnic State University5, Brigham Young University6, University of Utah7, University of California, Riverside8, Goddard Space Flight Center9, University of Maryland, College Park10, University of California, Berkeley11, University of Southampton12, Western Kentucky University13, University of Northern Colorado14, Space Telescope Science Institute15, Texas A&M University16, Seoul National University17
TL;DR: In this paper, the authors present models of the Hβ-emitting broadline region (BLR) in seven Seyfert 1 galaxies from the Lick AGN Monitoring Project 2011 sample, drawing inferences on the BLR structure and dynamics as well as the mass of the central supermassive black hole.
Abstract: We present models of the Hβ-emitting broad-line region (BLR) in seven Seyfert 1 galaxies from the Lick AGN Monitoring Project 2011 sample, drawing inferences on the BLR structure and dynamics as well as the mass of the central supermassive black hole. We find that the BLR is generally a thick disk, viewed close to face-on, with preferential emission back toward the ionizing source. The dynamics in our sample range from near-circular elliptical orbits to inflowing or outflowing trajectories. We measure black hole masses of for PG 1310-108, for Mrk 50, for Mrk 141, for Mrk 279, for Mrk 1511, for NGC 4593, and for Zw 229-015. We use these black hole mass measurements along with cross-correlation time lags and line widths to recover the scale factor f used in traditional reverberation mapping measurements. Combining our results with other studies that use this modeling technique, which brings our sample size to 16, we calculate a scale factor that can be used for measuring black hole masses in other reverberation mapping campaigns. When using the root-mean-square (rms) spectrum and using the line dispersion to measure the line width, we find pred = 0.57 0.19. Finally, we search for correlations between f and other AGN and BLR parameters and find marginal evidence that f is correlated with M BH and the BLR inclination angle, but no significant evidence of a correlation with the AGN luminosity or Eddington ratio.
73 citations
TL;DR: In this article, a combination of reionization simulations and empirical ISM models was used to show that UV bright galaxies have 2 × higher transmission through the intergalactic medium than UV faint galaxies, and this boosted transmission is enhanced as the neutral fraction increases.
Abstract: Recent detections of Lyman alpha (Ly$\\alpha$) emission from $z>7.5$ galaxies were somewhat unexpected given a dearth of previous non-detections in this era when the intergalactic medium (IGM) is still highly neutral. But these detections were from UV bright galaxies which preferentially live in overdensities which reionize early and have significantly Doppler-shifted Ly$\\alpha$ line profiles emerging from their interstellar media (ISM), making them less affected by the global IGM state. Using a combination of reionization simulations and empirical ISM models we show, as a result of these two effects, UV bright galaxies have $>2\\times$ higher transmission through the $z\\sim7$ IGM than UV faint galaxies, and this boosted transmission is enhanced as the neutral fraction increases. The boosted transmission is not sufficient to explain the observed high Ly$\\alpha$ fraction of $M_\\mathrm{UV} \\lesssim -22$ galaxies (Stark et al. 2017), suggesting Ly$\\alpha$ emitted by these galaxies must be stronger than expected due to enhanced production and/or selection effects. Despite the bias of UV bright galaxies to reside in overdensities we show Ly$\\alpha$ observations of such galaxies can accurately measure the global neutral hydrogen fraction, particularly when Ly$\\alpha$ from UV faint galaxies is extinguished, making them ideal candidates for spectroscopic follow-up into the cosmic Dark Ages.
64 citations
TL;DR: In this paper, the authors used integral field spectrographs to simulate observations of lensed quasars and showed that spatially resolved kinematics of the deflector galaxy enables further progress by helping to break the mass-anisotropy degeneracy.
Abstract: Strongly gravitational lensed quasars can be used to measure the so-called time-delay distance D_Δt, and thus the Hubble constant H_0 and other cosmological parameters. Stellar kinematics of the deflector galaxy play an essential role in this measurement by: (i) helping break the mass-sheet degeneracy; (ii) determining in principle the angular diameter distance D_d to the deflector and thus further improving the cosmological constraints. In this paper we simulate observations of lensed quasars with integral field spectrographs and show that spatially resolved kinematics of the deflector enablesfurther progress by helping break the mass-anisotropy degeneracy. Furthermore, we use our simulations to obtain realistic error estimates with current/upcoming instruments like OSIRIS on Keck and NIRSPEC on the James Webb Space Telescope for both distances (typically ∼6 per cent on D_Δt and ∼10 per cent on D_d). We use the error estimates to compute cosmological forecasts for the sample of nine lenses that currently have well-measured time delays and deep Hubble Space Telescope images and for a sample of 40 lenses that is projected to be available in a few years through follow-up of candidates found in ongoing wide field surveys. We find that H_0 can be measured with 2 per cent (1 per cent) precision from nine (40) lenses in a flat Λcold dark mattercosmology. We study several other cosmological models beyond the flat Λcold dark matter model and find that time-delay lenses with spatially resolved kinematics can greatly improve the precision of the cosmological parameters measured by cosmic microwave background data.
63 citations
TL;DR: In this article, a weak gravitational lensing measurement of the external convergence along the line of sight to the quadruply lensed quasar HE 0435-1223 was presented, which showed that the region in close proximity to the lens has an estimated external convergence of kappa = -0.012 (−0.013) + 0.020) and is hence marginally underdense.
Abstract: We present a weak gravitational lensing measurement of the external convergence along the line of sight to the quadruply lensed quasar HE 0435-1223. Using deep r-band images from Subaru Suprime Cam, we observe galaxies down to a 3 sigma limiting magnitude of similar to 26 mag resulting in a source galaxy density of 14 galaxies per square arcminute after redshift-based cuts. Using an inpainting technique and multiscale entropy filtering algorithm, we find that the region in close proximity to the lens has an estimated external convergence of kappa = -0.012(-0.013)(+0.020) and is hence marginally underdense. We also rule out the presence of any halo with a mass greater than M-vir = 1.6 x 10(14)h(-1)M(circle dot) (68 per cent confidence limit). Our results, consistent with previous studies of this lens, confirm that the intervening mass along the line of sight to HE0435-1223 does not affect significantly the cosmological results inferred from the time-delay measurements of that specific object.
École Polytechnique Fédérale de Lausanne1, Valparaiso University2, University of California, Davis3, Max Planck Society4, Andrés Bello National University5, University of California, Los Angeles6, Stanford University7, Fermilab8, University of Chicago9, Academia Sinica10, Technische Universität München11, Pontifical Catholic University of Chile12, Millennium Institute13, University of Liège14
TL;DR: In this article, the authors present time-delay estimates for the quadruply imaged quasar PG 1115+080, based on almost daily observations for seven months at the ESO MPIA 2.2 m telescope at La Silla Observatory, reaching a signal-to-noise ratio of about 1000 per quasar image.
Abstract: We present time-delay estimates for the quadruply imaged quasar PG 1115+080. Our results are based on almost daily observations for seven months at the ESO MPIA 2.2 m telescope at La Silla Observatory, reaching a signal-to-noise ratio of about 1000 per quasar image. In addition, we re-analyze existing light curves from the literature that we complete with an additional three seasons of monitoring with the Mercator telescope at La Palma Observatory. When exploring the possible source of bias we considered the so-called microlensing time delay, a potential source of systematic error so far never directly accounted for in previous time-delay publications. In 15 yr of data on PG 1115+080, we find no strong evidence of microlensing time delay. Therefore not accounting for this effect, our time-delay estimates on the individual data sets are in good agreement with each other and with the literature. Combining the data sets, we obtain the most precise time-delay estimates to date on PG 1115+080, with days (18.7% precision), days (11.1%) and days (8.5%). Turning these time delays into cosmological constraints is done in a companion paper that makes use of ground-based Adaptive Optics (AO) with the Keck telescope.
TL;DR: In this paper, the authors presented a full data analysis of the pure-parallel Hubble Space Telescope (HST) imaging observations in the Brightest of Reionizing Galaxies Survey (BoRG[z9]) in Cycle 22.
Abstract: We present a full data analysis of the pure-parallel Hubble Space Telescope (HST) imaging observations in the Brightest of Reionizing Galaxies Survey (BoRG[z9]) in Cycle 22. The medium-deep exposures with five HST/WFC3IR+UVIS filter bands from 79 independent sightlines (~370 arcmin^2) provide the least biased determination of number density for z>9 bright galaxies against cosmic variance. After a strict two-step selection for candidate galaxies, including dropout color and photometric redshift analyses, and revision of previous BoRG candidates, we identify one source at z~10 and two sources at z~9. The z~10 candidate shows evidence of line-of-sight lens magnification (mu~1.5), yet it appears surprisingly luminous (MUV ~ -22.6\pm0.3 mag), making it one of the brightest candidates at z > 8 known (~ 0.3 mag brighter than the z = 8.68 galaxy EGSY8p7, spectroscopically confirmed by Zitrin and collaborators). For z ~ 9 candidates, we include previous data points at fainter magnitudes and find that the data are well fitted by a Schechter luminosity function with alpha ~ -2.1, MUV ~ -21.5 mag, and log phi ~ -4.5 Mpc^-3mag^-1, for the first time without fixing any parameters. The inferred cosmic star formation rate density is consistent with unaccelerated evolution from lower redshift.
European Southern Observatory1, Stanford University2, Fermilab3, École Polytechnique Fédérale de Lausanne4, University of California, Berkeley5, Andrés Bello National University6, University of Cambridge7, Academia Sinica Institute of Astronomy and Astrophysics8, University of California, Davis9, University of Portsmouth10, Valparaiso University11, Universidade Federal do Rio Grande do Sul12, National Institutes of Natural Sciences, Japan13, Technische Universität München14, Max Planck Society15, Academia Sinica16, University College London17, Rhodes University18, University of Illinois at Urbana–Champaign19, IFAE20, Spanish National Research Council21, University of Pennsylvania22, California Institute of Technology23, University of Arizona24, Autonomous University of Madrid25, Lawrence Berkeley National Laboratory26, ETH Zurich27, University of California, Santa Cruz28, Ohio State University29, Harvard University30, Australian Astronomical Observatory31, University of São Paulo32, University of Sussex33, University of Michigan34, University of Southampton35, Brandeis University36, State University of Campinas37, Oak Ridge National Laboratory38
TL;DR: In the case of the STRIDES project as mentioned in this paper, the results of two selection methods, the outlier selection technique and a morphological algorithm, were presented, along with a model of a system that could be a lensed quasar in an unusual configuration.
Abstract: © 2018 The Author(s). The primary goals of the STRong lensing Insights into the Dark Energy Survey (STRIDES) collaboration are to measure the dark energy equation of state parameter and the free streaming length of dark matter. To this aim, STRIDES is discovering strongly lensed quasars in the imaging data of the Dark Energy Survey and following them up to measure time delays, high resolution imaging, and spectroscopy sufficient to construct accurate lens models. In this paper, we first present forecasts for STRIDES. Then, we describe the STRIDES classification scheme, and give an overview of the Fall 2016 follow-up campaign. We continue by detailing the results of two selection methods, the outlier selection technique and a morphological algorithm, and presenting lens models of a system that could possibly be a lensed quasar in an unusual configuration. We conclude with the summary statistics of the Fall 2016 campaign. Including searches presented in companion papers (Anguita et al.; Ostrovski et al.), STRIDES followed up 117 targets identifying 7 new strongly lensed systems, and 7 nearly identical quasars, which could be confirmed as lenses by the detection of the lens galaxy. 76 candidates were rejected and 27 remain otherwise inconclusive, for a success rate in the range of 6-35 per cent. This rate is comparable to that of previous searches like SDSS Quasar Lens Search even though the parent data set of STRIDES is purely photometric and our selection of candidates cannot rely on spectroscopic information.
TL;DR: In this article, the authors present a statistical technique, amendable to any parameterization of subhalo density profile and mass function, to probe dark matter on these scales with quadrupole image lenses.
Abstract: The free streaming length of dark matter particles determines the abundance of structure on sub-galactic scales. We present a statistical technique, amendable to any parameterization of subhalo density profile and mass function, to probe dark matter on these scales with quadrupole image lenses. We consider a warm dark matter particle with a mass function characterized by a normalization and free streaming scale $m_{\rm{hm}}$. We forecast bounds on dark matter warmth for 120-180 lenses, attainable with future surveys, at typical lens (source) redshifts of 0.5 (1.5) in early-type galaxies with velocity dispersions of 220-270 km/sec. We demonstrate that limits on $m_{\rm{hm}}$ deteriorate rapidly with increasing uncertainty in image fluxes, underscoring the importance of precise measurements and accurate lens models. For our forecasts, we assume the deflectors in the lens sample do not exhibit complex morphologies, so we neglect systematic errors in their modeling. Omitting the additional signal from line of sight halos, our constraints underestimate the true power of the method. Assuming cold dark matter, for a low normalization, corresponding the destruction of all subhalos within the host scale radius, we forecast $2\sigma$ bounds on $m_{\rm{hm}}$ (thermal relic mass) of $10^{7.5} \ (5.0)$, $10^{8} \ (3.6)$, and $10^{8.5} \ (2.7) \ M_{\odot} \left(\rm{keV}\right)$ for flux errors of $2\%$, $4\%$, and $8\%$. With a higher normalization, these constraints improve to $10^{7.2} \ (6.6)$, $10^{7.5} \ (5.3) $, and $10^{7.8} \ (4.3) \ M_{\odot} \left(\rm{keV}\right)$ with 120 systems. We are also able to measure the normalization of the mass function, which has implications for baryonic feedback models and tidal stripping.
Massachusetts Institute of Technology1, Ohio State University2, University of St Andrews3, Space Telescope Science Institute4, Georgia State University5, Pennsylvania State University6, Morehead State University7, California Institute of Technology8, University of California, Irvine9, Sul Ross State University10, University of Wyoming11, Georgetown University12, University of Missouri13, Georgia Institute of Technology14, Brigham Young University15, Tel Aviv University16, University of Melbourne17, Columbia University18, United States Naval Academy19, Australian National University20, Harvard University21, University of Illinois at Urbana–Champaign22, University of Haifa23, University of Michigan24, Texas Tech University25, Universidade Federal do Rio Grande do Sul26, Carnegie Learning27, Vanderbilt University28, University of California, Los Angeles29, University of California, Davis30, University of Bath31, Technion – Israel Institute of Technology32, University of Johannesburg33
TL;DR: In this paper, the authors acknowledge the receipt of research grants from the National Research Foundation (NRF) of South Africa and the National Science Foundation (NSF) Graduate Research Fellowship Program under Grant No. DGE-0822215.
Abstract: M.M.F. acknowledges financial support from a Presidential Fellowship awarded by The Ohio State University Graduate School. NSF grant AST-1008882 supported M.M.F., G.D.R., B.M.P., and R.W.P. M.C.B. gratefully acknowledges support through NSF CAREER grant AST-1253702 to Georgia State University. K.D.D. is supported by an NSF AAPF fellowship awarded under NSF grant AST-1302093. C.S.K. is supported by NSF grant AST-1515876. K.H. acknowledges support from STFC grant ST/M001296/1. This material is based in part upon work supported by the National Science Foundation (NSF) Graduate Research Fellowship Program under Grant No. DGE-0822215, awarded to C.B.H., and A.M.M. acknowledges the support of NSF grant AST-1211146. J.T. acknowledges support from NSF grant AST-1411685. Work by S.V. Jr. is supported by the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1343012. Work by W.Z. was supported by NSF grant AST-1516842. T.W.-S.H. is supported by the DOE Computational Science Graduate Fellowship, grant number DE-FG02-97ER25308. E.R.C. and S.M.C. gratefully acknowledge the receipt of research grants from the National Research Foundation (NRF) of South Africa. T.T. acknowledges support by the National Science Foundation through grant AST-1412315 "Collaborative Research: New Frontiers in Reverberation Mapping," and by the Packard Foundation through a Packard Research Fellowship. D.J.S. acknowledges support from NSF grants AST-1412504 and AST-1517649. A.J.B. and L.P. have been supported by NSF grant AST-1412693. B.J.S. is supported by NASA through Hubble Fellowship grant HF-51348.001 awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555. M.C.B. acknowledges support through grant HST GO-13816 from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.
TL;DR: In this paper, a combination of reionization simulations and empirical ISM models was used to show that UV bright galaxies in overdensities have 2 × higher transmission through the IGM than typical field galaxies, and this boosted transmission is enhanced as the neutral fraction increases.
Abstract: Recent detections of Lyman alpha (Ly$\alpha$) emission from $z>7.5$ galaxies were somewhat unexpected given a dearth of previous non-detections in this era when the intergalactic medium (IGM) is still highly neutral. But these detections were from UV bright galaxies, which preferentially live in overdensities which reionize early, and have significantly Doppler-shifted Ly$\alpha$ line profiles emerging from their interstellar media (ISM), making them less affected by the global IGM state. Using a combination of reionization simulations and empirical ISM models we show, as a result of these two effects, UV bright galaxies in overdensities have $>2\times$ higher transmission through the $z\sim7$ IGM than typical field galaxies, and this boosted transmission is enhanced as the neutral fraction increases. The boosted transmission is not sufficient to explain the observed high Ly$\alpha$ fraction of $M_\mathrm{UV} \lesssim -22$ galaxies (Stark et al. 2017), suggesting Ly$\alpha$ emitted by these galaxies must be stronger than expected due to enhanced production and/or selection effects. Despite the bias of UV bright galaxies to reside in overdensities we show Ly$\alpha$ observations of such galaxies can accurately measure the global neutral hydrogen fraction, particularly when Ly$\alpha$ from UV faint galaxies is extinguished, making them ideal candidates for spectroscopic follow-up into the cosmic Dark Ages.
European Southern Observatory1, Fermilab2, Andrés Bello National University3, Massachusetts Institute of Technology4, University of Valparaíso5, ETH Zurich6, University of Cambridge7, École Polytechnique Fédérale de Lausanne8, University of California, Davis9, University of Tokyo10, Stanford University11, Max Planck Society12, Swinburne University of Technology13, Rhodes University14, University College London15, Institut d'Astrophysique de Paris16, Carnegie Institution for Science17, Autonomous University of Barcelona18, University of Pennsylvania19, Indian Institute of Technology, Hyderabad20, California Institute of Technology21, Autonomous University of Madrid22, University of Michigan23, University of Illinois at Urbana–Champaign24, Ohio State University25, University of Washington26, Australian Astronomical Observatory27, University of São Paulo28, Universidade Federal do Rio Grande do Sul29, University of Southampton30, State University of Campinas31, Oak Ridge National Laboratory32
TL;DR: In this paper, the first strongly lensed quasars were discovered from a combined search in WISE and Gaia-DR1 over the DES footprint, and their Einstein radii span a range between 2.0 arcsec and 0.4 arcsec.
Abstract: We report the discovery, spectroscopic confirmation, and first lens models of the first, strongly lensed quasars from a combined search in WISE and Gaia-DR1 over the DES footprint. Their Einstein radii span a range between ≈2.0 arcsec and ≈0.4 arcsec. Two of these (WGD2038-4008, RA = 20:38:02.65, Dec.=-40:08:14.64; WGD2021-4115, RA = 20:21:39.45, Dec. = -41:15:57.11) also have confirmed deflector redshifts. The four-image lens WGD2038-4008, with source and deflector redshifts s = 0.777 ± 0.001 and zl = 0.230 ± 0.002, respectively, has a deflector with radius Reff ≈ 3.4 arcsec, stellar mass log(M*/M⊙) = 11.64+0.20
-0.43, and extended isophotal shape variation. Simple lens models yield Einstein radii RE = (1.30 ± 0.04) arcsec, axis ratio q = 0.75 ± 0.1 (compatible with that of the starlight) and considerable shear-ellipticity degeneracies. The two-image lens WGD2021-4115 has zs = 1.390 ± 0.001 and zl = 0.335 ± 0.002, and Einstein radius RE = (1.1 ± 0.1) arcsec, but higher-resolution imaging is needed to accurately separate the deflector and faint quasar image. Analogous lens model degeneracies hold for the other six lenses (J0146-1133, J0150-4041, J0235-2433, J0245-0556, J0259-2338, and J0508-2748) shown in this paper.
TL;DR: Woo et al. as mentioned in this paper presented the single-epoch black hole mass (M$_{\rm BH}$) calibrations based on the rest-frame UV and optical measurements of Mg II 2798\AA and H$\beta$ 4861\AA lines and AGN continuum.
Abstract: Author(s): Woo, Jong-Hak; Le, Huynh Anh N; Karouzos, Marios; Park, Dawoo; Park, Daeseong; Malkan, Matthew A; Treu, Tommaso; Bennert, Vardha N | Abstract: We present the single-epoch black hole mass (M$_{\rm BH}$) calibrations based on the rest-frame UV and optical measurements of Mg II 2798\AA\ and H$\beta$ 4861\AA\ lines and AGN continuum, using a sample of 52 moderate-luminosity AGNs at z$\sim$0.4 and z$\sim$0.6 with high-quality Keck spectra. We combine this sample with a large number of luminous AGNs from the Sloan Digital Sky Survey to increase the dynamic range for a better comparison of UV and optical velocity and luminosity measurements. With respect to the reference M$_{\rm BH}$ based on the line dispersion of H$\beta$ and continuum luminosity at 5100\AA, we calibrate the UV and optical mass estimators, by determining the best-fit values of the coefficients in the mass equation. By investigating whether the UV estimators show systematic trend with Eddington ratio, FWHM of H$\beta$, the Fe II strength, and the UV/optical slope, we find no significant bias except for the slope. By fitting the systematic difference of Mg II-based and H$\beta$-based masses with the L$_{3000}$/L$_{5100}$ ratio, we provide a correction term as a function of the spectral index as $\Delta$C = 0.24 (1+$\alpha_{\lambda}$) + 0.17, which can be added to the Mg II-based mass estimators if the spectral slope can be well determined. The derived UV mass estimators typically show $g$$\sim$0.2 dex intrinsic scatter with respect to H$\beta$-based M$_{\rm BH}$, suggesting that the UV-based mass has an additional uncertainty of $\sim$0.2 dex, even if high quality rest-frame UV spectra are available.
TL;DR: In this paper, a model with a radial gradient in the stellar mass-to-light ratio (M/L) is used to fit the data with models of varying complexity.
Abstract: The initial mass function (IMF) for massive galaxies can be constrained by combining stellar dynamics with strong gravitational lensing. However, this method is limited by degeneracies between the density profile of dark matter and the stellar mass-to-light ratio (M/L). In this work, we reduce this degeneracy by combining weak lensing together with strong lensing and stellar kinematics. Our analysis is based on two galaxy samples: 45 strong lenses from the SLACS survey and 1700 massive quiescent galaxies from the Sloan Digital Sky Survey main spectroscopic sample with weak lensing measurements from the Hyper Suprime-Cam survey. We use a Bayesian hierarchical approach to jointly model all three observables. We fit the data with models of varying complexity and show that a model with a radial gradient in the stellar M/L is required to simultaneously describe both galaxy samples. This result is driven by a subset of strong lenses with very steep total density profile that cannot be fitted by models with no gradient. Our measurements are unable to determine whether gradients are due to variations in stellar population parameters at fixed IMF, or to gradients in the IMF itself. The inclusion of M_*/L gradients decreases dramatically the inferred IMF normalization, compared to previous lensing-based studies, with the exact value depending on the assumed dark matter profile. The main effect of strong lensing selection is to shift the stellar mass distribution towards the high-mass end, while the halo mass and stellar IMF distribution at fixed stellar mass are not significantly affected.
TL;DR: In this paper, the star formation histories (SFHs) of 24 massive galaxies at 1.6 50% of their extant masses by ~1.5 Gyr before the time of observed redshifts were studied.
Abstract: Observations have revealed massive (logM*/Msun>11) galaxies that were already dead when the universe was only ~2 Gyr. Given the short time before these galaxies were quenched, their past histories and quenching mechanism(s) are of particular interest. In this paper, we study star formation histories (SFHs) of 24 massive galaxies at 1.6 50% of their extant masses by ~1.5 Gyr before the time of observed redshifts, with a trend where more massive galaxies form earlier. Their stellar-phase metallicities are already compatible with those of local early-type galaxies, with a median value of logZ*/Zsun=0.25 and scatter of ~0.15dex. In combination with the reconstructed SFHs, we reveal their rapid metallicity evolution from z~5.5 to ~2.2 at a rate of ~0.2dex/Gyr in log Z*/Zsun. Interestingly, the inferred stellar-phase metallicities are, when compared at half-mass time, ~0.25dex higher than observed gas-phase metallicities of star forming galaxies. While systematic uncertainties remain, this may imply that these quenched galaxies have continued low-level star formation, rather than abruptly terminating their star formation activity, and kept enhancing their metallicity until recently.
University of South Carolina1, University of California, Davis2, Space Telescope Science Institute3, University of the Basque Country4, Ikerbasque5, Kapteyn Astronomical Institute6, University of Ferrara7, Max Planck Society8, Spanish National Research Council9, University of California, Berkeley10, University of California, Santa Cruz11, Harvard University12, New York University13, American Museum of Natural History14, University of Milan15, University of Copenhagen16, California Institute of Technology17, Durham University18, University of KwaZulu-Natal19, Rutgers University20, University of Tokyo21, University of Minnesota22, University of California, Santa Barbara23, Las Cumbres Observatory Global Telescope Network24, University of California, Riverside25, University of São Paulo26, Institute for the Physics and Mathematics of the Universe27, École normale supérieure de Lyon28, Johns Hopkins University29, Leibniz Institute for Astrophysics Potsdam30, University of Michigan31, Academia Sinica32, Technische Universität München33, University of California, Los Angeles34, University of Arizona35, Ben-Gurion University of the Negev36
TL;DR: In this article, the authors describe two unusual transient events discovered in a Hubble Space Telescope program that combined these techniques with high-cadence imaging on a field with a strong-lensing galaxy cluster.
Abstract: A massive galaxy cluster can serve as a magnifying glass for distant stellar populations, as strong gravitational lensing magnifies background galaxies and exposes details that are otherwise undetectable. In time-domain astronomy, imaging programmes with a short cadence are able to detect rapidly evolving transients, previously unseen by surveys designed for slowly evolving supernovae. Here, we describe two unusual transient events discovered in a Hubble Space Telescope programme that combined these techniques with high-cadence imaging on a field with a strong-lensing galaxy cluster. These transients were faster and fainter than any supernovae, but substantially more luminous than a classical nova. We find that they can be explained as separate eruptions of a luminous blue variable star or a recurrent nova, or as an unrelated pair of stellar microlensing events. To distinguish between these hypotheses will require clarification of the cluster lens models, along with more high-cadence imaging of the field that could detect related transient episodes. This discovery suggests that the intersection of strong lensing with high-cadence transient surveys may be a fruitful path for future astrophysical transient studies.
Harvard University1, University of California, Irvine2, University of St Andrews3, University of California, Los Angeles4, University of Auckland5, California Polytechnic State University6, University of California, Riverside7, University of California, Berkeley8, University of Arizona9, Las Cumbres Observatory Global Telescope Network10, Seoul National University11, University of Southampton12, Brigham Young University13, University of Nebraska at Kearney14, Space Telescope Science Institute15, Texas A&M University16, University of Johannesburg17
TL;DR: In this paper, the authors used a geometric and dynamical model for the broad line region (BLR) of the Seyfert 1 galaxy Arp 151 to constrain the systematic uncertainties in nonvarying parameters such as the black hole mass.
Abstract: The Seyfert 1 galaxy Arp 151 was monitored as part of three reverberation mapping campaigns spanning 2008-2015. We present modeling of these velocity-resolved reverberation mapping data sets using a geometric and dynamical model for the broad-line region (BLR). By modeling each of the three data sets independently, we infer the evolution of the BLR structure in Arp 151 over a total of 7 yr and constrain the systematic uncertainties in nonvarying parameters such as the black hole mass. We find that the BLR geometry of a thick disk viewed close to face-on is stable over this time, although the size of the BLR grows by a factor of ∼2. The dynamics of the BLR are dominated by inflow, and the inferred black hole mass is consistent for the three data sets, despite the increase in BLR size. Combining the inference for the three data sets yields a black hole mass and statistical uncertainty of log10(/) = with a standard deviation in individual measurements of 0.13 dex.
TL;DR: In this article, a new technique that uses the cosmological time-delay ratios and simulated microlensing maps within a Bayesian framework was developed to limit the allowed combinations of micro-lensing delays and thus to lessen the uncertainties due to the proposed effect.
Abstract: Time-delay strong lensing provides a unique way to directly measure the Hubble constant (H-0). The precision of the H-0 measurement depends on the uncertainties in the time-delay measurements, the mass distribution of the main deflector(s), and the mass distribution along the line of sight. Tie & Kochanek have proposed a new microlensing effect on time delays based on differential magnification of the coherent accretion disc variability of the lensed quasar. If real, this effect could significantly broaden the uncertainty on the time-delay measurements by up to 30 per cent for lens systems such as PG 1115+080, which have relatively short time delays and monitoring over several different epochs. In this paper we develop a new technique that uses the cosmological time-delay ratios and simulated microlensing maps within a Bayesian framework in order to limit the allowed combinations of microlensing delays and thus to lessen the uncertainties due to the proposed effect. We show that, under the assumption of Tie & Kochanek, the uncertainty on the time-delay distance (D-Delta t, which is proportional to 1/H-0) of the short time-delay (similar to 18 d) lens, PG 1115+080, increases from similar to 7 per cent to similar to 10 per cent by simultaneously fitting the three time-delay measurements from the three different data sets across 20 yr, while in the case of the long time-delay (similar to 90 d) lens, the microlensing effect on time delays is negligible as the uncertainty on D-Delta t of RXJ 1131-1231 only increases from similar to 2.5 per cent to similar to 2.6 per cent.
TL;DR: Hoag et al. as mentioned in this paper presented deep spectroscopic observations of a Lyman break galaxy (LBG) candidate (hereafter MACS1149-JD) at z ∼ 9.5 with the Hubble Space Telescope (HST) WFC3/IR grisms.
Abstract: Author(s): Hoag, A; Bradac, M; Brammer, G; Huang, KH; Treu, T; Mason, CA; Castellano, M; Criscienzo, MD; Jones, T; Kelly, P; Pentericci, L; Ryan, R; Schmidt, K; Trenti, M | Abstract: We present deep spectroscopic observations of a Lyman break galaxy (LBG) candidate (hereafter MACS1149-JD) at z ∼ 9.5 with the Hubble Space Telescope (HST) WFC3/IR grisms. The grism observations were taken at four distinct position angles, totaling 34 orbits with the G141 grism, although only 19 of the orbits are relatively uncontaminated along the trace of MACS1149-JD. We fit a three-parameter (z, F160W mag, and Lyα equivalent width [EW]) LBG template to the three least contaminated grism position angles using a Markov chain Monte Carlo approach. The grism data alone are best fit with a redshift of (68% confidence), in good agreement with our photometric estimate of (68% confidence). Our analysis rules out Lyα emission from MACS1149-JD above a 3σ EW of 21 A, consistent with a highly neutral IGM. We explore a scenario where the red Spitzer/IRAC [3.6]-[4.5] color of the galaxy previously pointed out in the literature is due to strong rest-frame optical emission lines from a very young stellar population rather than a 4000 A break. We find that while this can provide an explanation for the observed IRAC color, it requires a lower redshift (z ≲ 9.1), which is less preferred by the HST imaging data. The grism data are consistent with both scenarios, indicating that the red IRAC color can still be explained by a 4000 A break, characteristic of a relatively evolved stellar population. In this interpretation, the photometry indicates that a Myr stellar population is already present in this galaxy only ∼500 Myr after the big bang.
TL;DR: In this paper, the first sub-kiloparsec spatial resolution measurements of strongly inverted gas-phase metallicity gradients in two dwarf galaxies at 2.1 and 2.5 kpc were reported.
Abstract: We report the first sub-kiloparsec spatial resolution measurements of strongly inverted gas-phase metallicity gradients in two dwarf galaxies at $z$$\sim$2. The galaxies have stellar masses $\sim$$10^9M_\odot$, specific star-formation rate $\sim$20 Gyr$^{-1}$, and global metallicity $12+\log({\rm O/H})\sim8.1$ (1/4 solar), assuming the Maiolino et al. (2008) strong line calibrations of OIII/Hb and OII/Hb. Their metallicity radial gradients are measured to be highly inverted, i.e., 0.122$\pm$0.008 and 0.111$\pm$0.017 dex/kpc, which is hitherto unseen at such small masses in similar redshift ranges. From the Hubble Space Telescope observations of the source nebular emission and stellar continuum, we present the 2-dimensional spatial maps of star-formation rate surface density, stellar population age, and gas fraction, which show that our galaxies are currently undergoing rapid mass assembly via disk inside-out growth. More importantly, using a simple chemical evolution model, we find that the gas fractions for different metallicity regions cannot be explained by pure gas accretion. Our spatially resolved analysis based on a more advanced gas regulator model results in a spatial map of net gaseous outflows, triggered by active central starbursts, that potentially play a significant role in shaping the spatial distribution of metallicity by effectively transporting stellar nucleosynthesis yields outwards. The relation between wind mass loading factors and stellar surface densities measured in different regions of our galaxies shows that a single type of wind mechanism, driven by either energy or momentum conservation, cannot explain the entire galaxy. These sources present a unique constraint on the effects of gas flows on the early phase of disk growth from the perspective of spatially resolved chemical evolution within individual systems.
TL;DR: In this paper, the discovery results from a quasar lens search in the ATLAS-DR3 public footprint were reported, which yielded seven pairs of quasars exhibiting the same lines at the same redshift and monotonic flux ratios with wavelength (hereafter NIQs, nearly identical quasar pairs).
Abstract: We report on discovery results from a quasar lens search in the ATLAS-DR3 public footprint. Spectroscopic follow-up campaigns, conducted at the 2.6 m Nordic Optical Telescope (La Palma) and 3.6 m New Technology Telescope (La Silla) in 2016, yielded seven pairs of quasars exhibiting the same lines at the same redshift and monotonic flux ratios with wavelength (hereafter NIQs, nearly identical quasar pairs). Magellan spectra of A0140−1152 (01h40m03
s.
0–11d52m19
s.
0, zs = 1.807) confirm it as a lens with deflector at zl = 0.277 and Einstein radius θE = (0.73 ± 0.02) arcsec. Follow-up imaging of the NIQ A2213−2652 (22h13m38
s.
4–26d52m27
s.
1) reveals the deflector galaxy and confirms it as a lens. We show the use of spatial resolution from the Gaia mission to select lenses and list additional systems from a WISE-Gaia-ATLAS search, yielding three additional lenses (02h35m27
s.
4–24d33m13
s.
2, 02h59m33s–23d38m01
s.
8, 01h46m32
s.
9–11d33m39
s.
0). The overall sample consists of 11 lenses/NIQs, plus three lenses known before 2016, over the ATLAS-DR3 footprint (≈3500 deg2). Finally, we discuss future prospects for objective classification of pair/NIQ/contaminant spectra.
University of Copenhagen1, University of Milan2, University of Ferrara3, INAF4, Max Planck Society5, Academia Sinica6, Technische Universität München7, Ludwig Maximilian University of Munich8, Kapteyn Astronomical Institute9, University of California, Berkeley10, University of South Carolina11, University of California, Los Angeles12
TL;DR: In this paper, the authors used the observed positions of 89 multiple images, with extensive spectroscopic information, from 28 background sources and the measured time delays between the images S1-S4 and SX of supernova "Refsdal" to estimate the Hubble constant.
Abstract: Realizing Refsdal's original idea from 1964, we present estimates of the Hubble constant that are complementary to and potentially competitive with those of other cosmological probes We use the observed positions of 89 multiple images, with extensive spectroscopic information, from 28 background sources and the measured time delays between the images S1-S4 and SX of supernova "Refsdal" ($z = 1489$), which were obtained thanks to Hubble Space Telescope (HST) deep imaging and Multi Unit Spectroscopic Explorer (MUSE) data We extend the strong lensing modeling of the Hubble Frontier Fields (HFF) galaxy cluster MACS J11495$+$2223 ($z = 0542$), published by Grillo et al (2016), and explore different $\Lambda$CDM models Taking advantage of the lensing information associated to the presence of very close pairs of multiple images at various redshifts and to the extended surface brightness distribution of the SN Refsdal host, we can reconstruct the total mass density profile of the cluster very precisely The combined dependence of the multiple image positions and time delays on the cosmological parameters allows us to infer the values of $H_{0}$ and $\Omega_{\rm m}$ with relative (1$\sigma$) statistical errors of, respectively, 6% (7%) and 31% (26%) in flat (general) cosmological models, assuming a conservative 3% uncertainty on the final time delay of image SX and, remarkably, no priors from other cosmological experiments Our best estimate of $H_{0}$, based on the model described in this work, will be presented when the final time-delay measurement becomes available Our results show that it is possible to utilize time delays in lens galaxy clusters as an important alternative tool for measuring the expansion rate and the geometry of the Universe
TL;DR: In this article, a followup imaging of two bright (L > L*) galaxy candidates at z > 8 from the Brightest of Reionizing Galaxies (BoRG) survey with the F098M filter was presented.
Abstract: We present followup imaging of two bright (L > L*) galaxy candidates at z > 8 from the Brightest of Reionizing Galaxies (BoRG) survey with the F098M filter on HST/WFC3. The F098M filter provides an additional constraint on the flux blueward of the spectral break, and the observations are designed to discriminate between low- and high-z photometric redshift solutions for these galaxies. Our results confirm one galaxy, BoRG 0116+1425 747, as a highly probable z ~ 8 source, but reveal that BoRG 0116+1425 630 - previously the brightest known z > 8 candidate (mAB = 24.5) - is likely to be a z ~ 2 interloper. As this source was substantially brighter than any other z > 8 candidate, removing it from the sample has a significant impact on the derived UV luminosity function in this epoch. We show that while previous BoRG results favored a shallow power-law decline in the bright end of the luminosity function prior to reionization, there is now no evidence for departure from a Schechter function form and therefore no evidence for a difference in galaxy formation processes before and after reionization.
TL;DR: In this article, the authors presented the discovery of 3 quasar lenses in the Sloan Digital Sky Survey (SDSS), selected using two novel photometry-based selection techniques.
Abstract: We present the discovery of 3 quasar lenses in the Sloan Digital Sky Survey (SDSS), selected using two novel photometry-based selection techniques. The J0941+0518 system, with two point sources separated by 5.46" on either side of a galaxy, has source and lens redshifts $z_s = 1.54$ and $z_l = 0.343$. The AO-assisted images of J2211+1929 show two point sources separated by 1.04", corresponding to the same quasar at $z_s = 1.07,$ besides the lens galaxy and Einstein ring. Images of J2257+2349 show two point sources separated by 1.67" on either side of an E/S0 galaxy. The extracted spectra show two images of the same quasar at redshift $z_s = 2.10$. In total, the two selection techniques identified 309 lens candidates, including 47 known lenses, and 6 previously ruled out candidates. 55 of the remaining candidates were observed using NIRC2 and ESI at Keck Observatory, EFOSC2 at the ESO-NTT (La Silla), and SAM and the Goodman spectrograph at SOAR. Of the candidates observed, 3 were confirmed as lenses, 36 were ruled out, and 16 remain inconclusive. Taking into account that we recovered known lenses, this gives us a success rate of at least 50/309 (16%). This initial campaign demonstrates the power of purely photometric selection techniques in finding lensed quasars. Developing and refining these techniques is essential for efficient identification of these rare lenses in ongoing and future photometric surveys.