High-precision cosmological probes have revealed a small but significant tension between the parameters measured with different techniques, among which there is one based on time delays in gravitational lenses. We discuss a new way of using time delays for cosmology, taking advantage of the extreme precision expected for lensed fast radio bursts (FRBs), which are short flashes of radio emission originating at cosmological distances. With coherent methods, the achievable precision is sufficient for measuring how time delays change over the months and years, which can also be interpreted as differential redshifts between the images. It turns out that uncertainties arising from the unknown mass distribution of gravitational lenses can be eliminated by combining time delays with their time derivatives. Other effects, most importantly relative proper motions, can be measured accurately and disentangled from the cosmological effects. With a mock sample of simulated lenses, we show that it may be possible to attain strong constraints on cosmological parameters. Finally, the lensed images can be used as galactic interferometer to resolve structures and motions of the burst sources with incredibly high resolution and help reveal their physical nature, which is currently unknown.
Fast radio bursts (FRBs) are highly dispersed and probably extragalactic radio flashes with millisecond-duration. Recently, the Canadian Hydrogen Intensity Mapping Experiment (using the CHIME/FRB instrument) has reported detections of 13 FRBs during a pre-commissioning phase. It is more exciting that one of the 13 FRBs is a second source of repeaters which suggests that CHIME/FRB and other wide-field sensitive radio telescopes will find a substantial population of repeating FRBs. We have proposed strongly lensed repeating FRBs as a precision cosmological probe, e.g. constraining the Hubble con…
We report the discovery of a gravitationally lensed quasar identified serendipitously in the Sloan Digital Sky Survey (SDSS). The object, SDSS J094604.90+183541.8, was initially targeted for spectroscopy as a luminous red galaxy, but the SDSS spectrum has the features of both a z=0.388 galaxy and a z=4.8 quasar. We have obtained additional imaging that resolves the system into two quasar images separated by 3.06 arcsec and a bright galaxy that is strongly blended with one of the quasar images. We confirm spectroscopically that the two quasar images represent a single lensed source at z=4.8 wit…
We report on a short XMM-Newton observation of the gravitationally-lensed, luminous infrared galaxy IRAS F10214+4724 at z=2.3. A faint X-ray source is detected at 4 sigma. The observed 0.5-2 keV (1.7-6.6 keV in the rest-frame) flux is 1.3e-15 erg/s/cm2 and the spectral slope in the rest-frame 1-10 keV band is Gamma~2. These results agree with those obtained from the Chandra X-ray Observatory, given the large uncertainties in both measurements. While possible evidence for excess emission above 5 keV is seen, we suspect this excess might be either spurious or not related to the infrared galaxy.
It is noted that the duration of a fast radio burst (FRB), about $10^{-3}$ s, is a smaller fraction of the time delay between multiple images of a source gravitationally lensed by a galaxy or galaxy cluster than the human lifetime is to the age of the universe. Thus repeating, strongly lensed FRBs may offer an unprecedented opportunity for observing cosmological evolution in "real time". The possibility is discussed of observing cosmic expansion, transverse proper motion, mass accretion and perhaps growth of density perturbations, as a function of redshift.
In the current paper we consider the prospects of observation of gravitationally lensed sources in far-infrared and submillimeter wavelength ranges by the future space telescopes equipped with actively cooled main mirrors. We consider the possibility of solving some of the important cosmological and astrophysical scientific tasks by observation of gravitationally lensed sources. The number counts of lensed sources for wavelengths from 70$μm$ up to 2000$μm$ were calculated. We discuss the distribution of lensed sources at different redshifts and magnification coefficients and also mass distribu…
The quasar SDSS J133401.39+331534.3 at z = 2.426 is found to be a two-image gravitationally lensed quasar with the image separation of 0.833. The object is first identified as a lensed quasar candidate in the Sloan Digital Sky Survey Quasar Lens Search, and then confirmed as a lensed system from follow-up observations at the Subaru and University of Hawaii 2.2-meter telescopes. We estimate the redshift of the lensing galaxy to be 0.557 based on absorption lines in the quasar spectra as well as the color of the galaxy. In particular, we observe the system with the Subaru Telescope AO188 adaptiv…
A Targeted Search for Variable Gravitationally Lensed Quasars
University of California, Los Angeles（加州大学洛杉矶分校）；Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）；University of San Francisco（旧金山大学）；Gemini Observatory / NSF’s NOIRLab（Gemini 天文台/美国国家科学基金会NOIRLab）；Kavli Institute for the Physics and Mathematics of the Universe, University of Tokyo（东京大学 Kavli宇宙物理与数学研究所）；Carnegie Mellon University（卡内基梅隆大学）；University of Hawaii（夏威夷大学）
Bright gravitationally lensed galaxies provide our most detailed view of galaxies at high redshift. Yet as a result of the small number of ultra-bright z~2 lensed systems with confirmed redshifts, most detailed spectroscopic studies have been limited in their scope. With the goal of increasing the number of bright lensed galaxies available for detailed follow-up, we have undertaken a spectroscopic campaign targeting wide separation (>3 arcsec) galaxy-galaxy lens candidates within the Sloan Digital Sky Survey (SDSS). Building on the earlier efforts of our CASSOWARY survey, we target a large sam…
We present and analyse near-infrared spectroscopy for a sample of 28 gravitationally- lensed star-forming galaxies in the redshift range 1.5 < z < 5, observed mostly with the Keck II telescope. With typical magnifications of ~1.5-4 magnitudes, our survey provides a valuable census of star formation rates, gas-phase metallicities and dynamical masses for a representative sample of low luminosity galaxies seen at a formative period in cosmic history. We find less evolution in the mass-metallicity relation compared to earlier work that focused on more luminous systems with z - 2-3, especially in …
The four-image gravitationally lensed quasar QSO 2237+0305 is microlensed by stars in the lens galaxy. The amplitude of microlensing variability can be used to infer the relative size of the quasar as a function of wavelength; this provides a test of quasar models. Toward this end, we present Spitzer Space Telescope Infrared Spectrograph and Infrared Array Camera (IRAC) observations of QSO 2237+0305, finding the following. (1) The infrared (IR) spectral energy distribution (SED) is similar to that of other bright radio-quiet quasars, contrary to an earlier claim. (2) A dusty torus model with a…
Fast Radio bursts (FRBs), bright transients with millisecond durations at $\sim$ GHz and typical redshifts probably $>0.8$, are likely to be gravitationally lensed by intervening galaxies. Since the time delay between images of strongly lensed FRB can be measured to extremely high precision because of the large ratio $\sim10^9$ between the typical galaxy-lensing delay time $\sim\mathcal{O}$(10 days) and the width of bursts $\sim\mathcal{O}$(ms), we propose strongly lensed FRBs as precision probes of the universe. We show that, within the flat $Λ$CDM model, the Hubble constant $H_0$ can be cons…
Recently, there have been two landmark discoveries of gravitationally lensed supernovae: the first multiply-imaged SN, "Refsdal", and the first Type Ia SN resolved into multiple images, SN iPTF16geu. Fitting the multiple light curves of such objects can deliver measurements of the lensing time delays, which are the difference in arrival times for the separate images. These measurements provide precise tests of lens models or constraints on the Hubble constant and other cosmological parameters that are independent of the local distance ladder. Over the next decade, accurate time delay measureme…
The jets image modelling of gravitationally lensed sources have been performed. Several basic models of the lens mass distribution were considered, in particular, a singular isothermal ellipsoid, an isothermal ellipsoid with the core, different multi-components models with the galactic disk, halo and bulge. The obtained jet images were compared as with each other as with results of observations. A significant dependence of the Hubble constant on the model parameters was revealed for B0218+357, when the circular structure was took into account.
When the light from a distant object passes very near to a foreground galaxy or cluster, gravitational lensing can cause it to appear as multiple images on the sky. If the source is variable, it can be used to constrain the cosmic expansion rate and dark energy models. Achieving these cosmological goals requires many lensed transients with precise time delay measurements. Lensed supernovae (SN) are attractive for this purpose because they have relatively simple photometric behavior, with well-understood light curve shapes and colours $-$ in contrast to the stochastic variation of quasars. Here…
Water masers are found in dense molecular clouds closely associated with supermassive black holes in the centres of active galaxies. Based upon the understanding of the local water maser luminosity function, it was expected that masers at intermediate and high redshifts would be extremely rare, but galaxies at redshifts z > 2 might be quite different from those found locally, not least because of more frequent mergers and interaction events. Using gravitational lensing as a tool to enable us to search higher redshifts than would otherwise be possible, we have embarked on a survey of lensed gal…
We present VLT/X-shooter spectra of 13 galaxies in the redshift range 1< z < 6, which are strongly lensed by massive galaxy clusters. Spectroscopic redshifts are measured for nine galaxies, while three sources have redshifts determined from continuum breaks in their spectra. The stellar masses of the galaxies span four orders of magnitude between 10^7 and 10^11 M_sun and have luminosities at 1500 A rest-frame between 0.004 and 9 L^* after correcting for the magnification. This allows us to probe a variety of galaxy types from young, low-mass starburst galaxies to massive evolved galaxies. The …
Cadenced optical imaging surveys in the next decade will be capable of detecting time-varying galaxy-scale strong gravitational lenses in large numbers, increasing the size of the statistically well-defined samples of multiply-imaged quasars by two orders of magnitude, and discovering the first strongly-lensed supernovae. We carry out a detailed calculation of the likely yields of several planned surveys, using realistic distributions for the lens and source properties and taking magnification bias and image configuration detectability into account. We find that upcoming wide-field synoptic su…
We apply the iterative MCS deconvolution method (ISMCS) to near-IR HST archives data of seven gravitationally lensed quasars currently monitored by the COSMOGRAIL collaboration: HE 0047-1756, RX J1131-1231, SDSS J1138+0314, SDSS J1155+6346, SDSS J1226-0006, WFI J2026-4536 and HS 2209+1914. In doing so, we obtain relative positions for the lensed images and shape parameters for the light distribution of the lensing galaxy in each system. The lensed image positions are derived with 1-2 mas accuracy. To predict time delays and to test the ability of simple mass models to reproduce the observed co…
Since their serendipitous discovery, Fast Radio Bursts (FRBs) have garnered a great deal of attention from both observers and theorists. A new class of radio telescopes with wide fields of view have enabled a rapid accumulation of FRB observations, confirming that FRBs originate from cosmological distances. The high occurrence rate of FRBs and the development of new instruments to observe them create opportunities for FRBs to be utilized for a host of astrophysical and cosmological studies. We focus on the rare, and as yet undetected, subset of FRBs that undergo repeated bursts and are strongl…
Strongly lensed supernovae can be detected as multiply imaged or highly magnified transients. In order to compare the performances of these two observational strategies, we calculate expected discovery rates as a function of survey depth in five grizy filters and for different classes of supernovae (Ia, IIP, IIL, Ibc and IIn). We find that detections via magnification is the only effective strategy for relatively shallow pre-LSST surveys. For survey depths about the LSST capacity, both strategies yield comparable numbers of lensed supernovae. Supernova samples from the two methods are to a lar…
We analyze all publicly available long-term optical observations of the gravitationally lensed quasar PG1115+080 for the purpose of estimating time delays between its four components. In particular, the light curves of PG1115+080 components obtained in 2001-2006 at Maidanak observatory (Uzbekistan) (Tsvetkova et al 2010} are considered. We find that the linear trend is observed in 2006 in light curves of all four components with fast variations only in the A1 and C components that can be due to microlensing and observational errors. Application of the MCCF method (Oknyansky 1993) to the photom…
Small galaxies consisting entirely of population III (pop III) stars may form at high redshifts, and could constitute one of the best probes of such stars. Here, we explore the prospects of detecting gravitationally lensed pop III galaxies behind the galaxy cluster J0717.5+3745 (J0717) with both the Hubble Space Telescope (HST) and the upcoming James Webb Space Telescope (JWST). By projecting simulated catalogs of pop III galaxies at z~7-15 through the J0717 magnification maps, we estimate the lensed number counts as a function of flux detection threshold. We find that the ongoing HST survey C…
We identify a binary black hole (BBH) merger that appears to be multiply lensed by an intervening galaxy. The LIGO/Virgo events GW170809 and GW170814 have indistinguishable waveforms separated by 5 days, and overlap on the sky within the 90\% credible region. Their strain amplitudes are also similar, implying a modest relative magnification ratio, as expected for a pair of lensed gravitational waves. The phase of the two events is also consistent with being the same, adding more evidence in support of both events originating from the same BBH merger. The difference in the published inferred di…
Strongly lensed variable quasars can serve as precise cosmological probes, provided that time delays between the image fluxes can be accurately measured. A number of methods have been proposed to address this problem. In this paper, we explore in detail a new approach based on kernel regression estimates, which is able to estimate a single time delay given several datasets for the same quasar. We develop realistic artificial data sets in order to carry out controlled experiments to test of performance of this new approach. We also test our method on real data from strongly lensed quasar Q0957+…
We present rest-frame optical spectra for a sample of 9 low-mass star-forming galaxies in the redshift range 1.5 < z < 3 which are gravitationally lensed by foreground clusters. We used Triplespec, an echelle spectrograph at the Palomar 200-inch telescope that is very effective for this purpose as it samples the entire near-infrared spectrum simultaneously. By measuring the flux of nebular emission lines we derive gas phase metallicities and star formation rates, and by fitting the optical to infrared spectral energy distributions we obtain stellar masses. Taking advantage of the high magnific…
Luminous extragalactic water masers are known to be associated with AGN and have provided accurate estimates for the mass of the central supermassive black hole and the size and structure of the accretion disk in nearby galaxies. To find water masers at much higher redshifts, we have begun a survey of known gravitationally lensed quasars and star-forming galaxies. In this paper, we present a search for 22 GHz (rest frame) water masers toward five dusty, gravitationally lensed quasars and star-forming galaxies at redshifts 2.3--2.9 with the Effelsberg telescope and the EVLA. Our observations do…
Lens modeling of resolved image data has advanced rapidly over the past two decades. More recently pixel-based approaches, wherein the source is reconstructed on an irregular or adaptive grid, have become popular. Generally, the source reconstruction takes place in a Bayesian framework and is guided by a set of sensible priors. We discuss the integration of a shapelets-based method into a Bayesian framework and quantify the required regularization. In such approaches, the source is reconstructed analytically, using a subset of a complete and orthonormal set of basis functions, known as shapele…
We present a spatio-temporal AI framework that concurrently exploits both the spatial and time-variable features of gravitationally lensed supernovae in optical images to ultimately aid in future discoveries of such exotic transients in wide-field surveys. Our spatio-temporal engine is designed using recurrent convolutional layers, while drawing from recent advances in variational inference to quantify approximate Bayesian uncertainties via a confidence score. Using simulated Young Supernova Experiment (YSE) images of lensed and non-lensed supernovae as a showcase, we find that the use of time…
High redshift Type Ia supernovae (SNe Ia) are likely to be gravitationally lensed by dark matter haloes of galaxies in the foreground. Since SNe Ia have very small dispersion after light curve shape and colour corrections, their brightness can be used to measure properties of the dark matter haloes via gravitational magnification. We use observations of galaxies and SNe Ia within the Great Observatories Origins Deep Survey (GOODS) to measure the relation between galaxy luminosity and dark matter halo mass. The relation we investigate is a scaling law between velocity dispersion and galaxy lumi…
We present the result of Subaru Telescope multi-band adaptive optics observations of the complex gravitationally lensed quasar SDSS J1405+0959, which is produced by two lensing galaxies. These observations reveal dramatically enhanced morphological detail, leading to the discovery of an additional object 0. 26'' from the secondary lensing galaxy, as well as three collinear clumps located in between the two lensing galaxies. The new object is likely to be the third quasar image, although the possibility that it is a galaxy cannot be entirely excluded. If confirmed via future observations, it wo…
We present 11.2 micron observations of the gravitationally lensed, radio-loud z_s=2.64 quasar MG0414+0534, obtained using the Michelle camera on Gemini North. We find a flux ratio anomaly of A2/A1= 0.93 +/- 0.02 for the quasar images A1 and A2. When combined with the 11.7 micron measurements from Minezaki et al. (2009), the A2/A1 flux ratio is nearly 5-sigma from the expected ratio for a model based on the two visible lens galaxies. The mid-IR flux ratio anomaly can be explained by a satellite (substructure), 0.3" Northeast of image A2, as can the detailed VLBI structures of the jet produced b…
We report the discovery of a unique gravitational lens system, SDSSJ2222+2745, producing five spectroscopically confirmed images of a z_s=2.82 quasar lensed by a foreground galaxy cluster at z_l=0.49. We also present photometric and spectroscopic evidence for a sixth lensed image of the same quasar. The maximum separation between the quasar images is 15.1". Both the large image separations and the high image multiplicity of the lensed quasar are in themselves exceptionally rare, and observing the combination of these two factors is an exceptionally unlikely occurrence in present datasets. This…
We present physical properties of two submillimeter selected gravitationally lensed sources, identified in the Herschel Astrophysical Terahertz Large Area Survey. These submillimeter galaxies (SMGs) have flux densities > 100 mJy at 500 um, but are not visible in existing optical imaging. We fit light profiles to each component of the lensing systems in Spitzer IRAC 3.6 and 4.5 um data and successfully disentangle the foreground lens from the background source in each case, providing important constraints on the spectral energy distributions (SEDs) of the background SMG at rest-frame optical-ne…
The Chandra observations of several gravitationally lensed quasars show evidence for flux and spectral variability of the X-ray emission that is uncorrelated between images and is thought to result from the microlensing by stars in the lensing galaxy. We report here on the most detailed modeling of such systems to date, including simulations of the emission of the Fe K-alpha fluorescent radiation from the accretion disk with a general relativistic ray tracing code, the use of realistic microlensing magnification maps derived from inverse ray shooting calculations, and the simulation of the lin…
We test the robustness of published time delays for 11 lensed quasars by using two techniques to measure time shifts in their light curves. We chose to use two fundamentally different techniques to determine time delays in gravitationally lensed quasars: a method based on fitting a numerical model and another one derived from the minimum dispersion method introduced by Pelt and collaborators. To analyse our sample in a homogeneous way and avoid bias caused by the choice of the method used, we apply both methods to 11 different lensed systems for which delays have been published: JVAS B0218+357…
We present an analysis of archival observations with the Atacama Large (sub-)Millimetre Array (ALMA) of the gravitationally lensed quasar MG J0414+0534, which show four compact images of the quasar and an Einstein ring from the dust associated with the quasar host galaxy. We confirm that the flux-ratio anomalies observed in the mid-infrared and radio persists into the sub-mm for the continuum images of the quasar. We report the detection of CO (11-10) spectral line emission, which traces a region of compact gas around the quasar nucleus. This line emission also shows evidence of a flux-ratio a…
We study the geometry and the internal structure of the outflowing wind from the accretion disk of a quasar by observing multiple sightlines with the aid of strong gravitational lensing. Using Subaru/HDS, we performed high-resolution ($R$ $\sim$ 36,000) spectroscopic observations of images A and B of the gravitationally lensed quasar SDSS J1029+2623 (at $z_{em}$ $\sim$ 2.197) whose image separation angle, $θ$ $\sim$ 22$^{\prime\prime}\!\!$.5, is the largest among those discovered so far. We confirm that the difference in absorption profiles in the images A and B discovered by Misawa et al. (20…
We report the serendipitous discovery of the first gravitationally lensed quasar candidate from Pan-STARRS. The grizy images reveal four point-like images with magnitudes between 14.9 mag and 18.1 mag. The colors of the point sources are similar, and they are more consistent with quasars than with stars or galaxies. The lensing galaxy is detected in the izy bands, with an inferred photometric redshift of ~0.6, lower than that of the point sources. We successfully model the system with a singular isothermal ellipsoid with shear, using the relative positions of the five objects as constraints. W…
Due to the expansion of our Universe, the redshift of distant objects changes with time. Although the amplitude of this redshift drift is small, it will be measurable with a decade-long campaigns on the next generation of telescopes. Here we present an alternative view of the redshift drift which captures the expansion of the universe in single epoch observations of the multiple images of gravitationally lensed sources. Considering a sufficiently massive lens, with an associated time delay of order decades, simultaneous photons arriving at a detector would have been emitted decades earlier in …
Secure confirmation that a gravitational wave (GW) has been gravitationally lensed would bring together these two pillars of General Relativity for the first time. This breakthrough is challenging for many reasons, including: GW sky localization uncertainties dwarf the angular scale of gravitational lensing, the mass and structure of gravitational lenses is diverse, the mass function of stellar remnant compact objects is not yet well constrained, and GW detectors do not operate continuously. We introduce a new approach that is agnostic to the mass and structure of the lenses, compare the effic…
Gravitationally lensed QSOs (GLQs) at redshift z = 1-2 play a key role in understanding the cosmic evolution of the innermost parts of active galaxies (black holes, accretion disks, coronas and internal jets), as well as the structure of galaxies at intermediate redshifts. With respect to studies of normal QSOs, GLQ programmes have several advantages. For example, a monitoring of GLQs may lead to unambiguous detections of intrinsic and extrinsic variations. Both kinds of variations can be used to discuss central engines in distant QSOs, and mass distributions and compositions of lensing galaxi…
We report the discovery of 13 confirmed two-image quasar lenses from a systematic search for gravitationally lensed quasars in the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS). We adopted a methodology similar to that used in the SDSS Quasar Lens Search (SQLS). In addition to the confirmed lenses, we report 11 quasar pairs with small angular separations ($\lesssim$2") confirmed from our spectroscopy, which are either projected pairs, physical binaries, or possibly quasar lens systems whose lens galaxies have not yet been detected. The newly discovered quasar lens system, SDSS J1452+…
We report the discovery of a multiply-imaged gravitationally lensed Type Ia supernova, iPTF16geu (SN 2016geu), at redshift $z=0.409$. This phenomenon could be identified because the light from the stellar explosion was magnified more than fifty times by the curvature of space around matter in an intervening galaxy. We used high spatial resolution observations to resolve four images of the lensed supernova, approximately 0.3" from the center of the foreground galaxy. The observations probe a physical scale of $\sim$1 kiloparsec, smaller than what is typical in other studies of extragalactic gra…
Recent work has demonstrated the potential of gravitationally lensed quasars to extend measurements of black hole spin out to high-redshift with the current generation of X-ray observatories. Here we present an analysis of a large sample of 27 lensed quasars in the redshift range 1.0<z<4.5 observed with Chandra, utilizing over 1.6 Ms of total observing time, focusing on the rest-frame iron K emission from these sources. Although the X-ray signal-to-noise (S/N) currently available does not permit the detection of iron emission from the inner accretion disk in individual cases in our sample, we …
An archival search for gamma-ray bursts gravitationally lensed by galaxy clusters
Institute of Cosmology and Gravitation, University of Portsmouth（宇宙学与引力研究所，朴茨茅斯大学）；School of Physics and Astronomy, University of Birmingham（物理与天文学学院，伯明翰大学）；Institute for Gravitational Wave Astronomy, University of Birmingham（引力波天文学研究所，伯明翰大学）；Department of Astrophysics, University of Vienna（天体物理学系，维也纳大学）
We present a list of 13 candidate gravitationally lensed submillimeter galaxies (SMGs) from 95 square degrees of the Herschel Multi-tiered Extragalactic Survey, a surface density of 0.14\pm0.04deg^{-2}. The selected sources have 500um flux densities (S_500) greater than 100mJy. Gravitational lensing is confirmed by follow-up observations in 9 of the 13 systems (70%), and the lensing status of the four remaining sources is undetermined. We also present a supplementary sample of 29 (0.31\pm0.06deg^{-2}) gravitationally lensed SMG candidates with S_500=80--100mJy, which are expected to contain a …
We present an analysis of seven strongly gravitationally lensed quasars and the corresponding constraints on the properties of dark matter. Our results are derived by modelling the lensed image positions and flux-ratios using a combination of smooth macro models and a population of low-mass haloes within the mass range 10^6 to 10^9 Msun. Our lens models explicitly include higher-order complexity in the form of stellar discs and luminous satellites, as well as low-mass haloes located along the observed lines of sight for the first time. Assuming a Cold Dark Matter (CDM) cosmology, we infer an a…
We present a machine learning method for the reconstruction of the undistorted images of background sources in strongly lensed systems. This method treats the source as a pixelated image and utilizes the Recurrent Inference Machine (RIM) to iteratively reconstruct the background source given a lens model. Our architecture learns to minimize the likelihood of the model parameters (source pixels) given the data using the physical forward model (ray tracing simulations) while implicitly learning the prior of the source structure from the training data. This results in better performance compared …
Follow-up observations of (sub-)mm-selected gravitationally-lensed systems have allowed a more detailed study of the dust-enshrouded phase of star-formation up to very early cosmic times. Here, the case of the gravitationally lensed merger in HATLAS J142935.3-002836 (also known as H1429-0028; z_lens=0.218, z_bkg=1.027) is revisited following recent developments in the literature and new APEX observations targeting two carbon monoxide (CO) rotational transitions J_up=3 and 6. We show that the line-profiles comprise three distinct velocity components, where the fainter high-velocity one is less …
The SKA era is set to revolutionize our understanding of neutral hydrogen (HI) in individual galaxies out to redshifts of z~0.8; and in the z > 6 intergalactic medium through the detection and imaging of cosmic reionization. Direct HI number density constraints will, nonetheless, remain relatively weak out to cosmic noon (z~2) - the epoch of peak star formation and black hole accretion - and beyond. However, as was demonstrated from the 1990s with molecular line observations, this can be overcome by utilising the natural amplification afforded by strong gravitational lensing, which results in …
Cross-referencing a watchlist of galaxy groups and clusters with transient detections from real-time streams of wide-field survey data is a promising method for discovering gravitationally lensed explosive transients including supernovae, kilonovae, gravitational waves and gamma-ray bursts in the next ten years. However, currently there exists no catalogue of objects with both sufficient angular extent and depth to adequately perform such a search. In this study, we develop a cluster-finding method capable of creating an all-sky list of galaxy group- and cluster-scale objects out to $z\simeq1$…
Using the Subaru 8.2m Telescope with an IRCS Echelle spectrograph, we obtained high-resolution (R=10,000) near-infrared (1.01-1.38 μm) spectra of images A and B of the gravitationally lensed QSO B1422+231 (z=3.628) consisting of four known lensed images. We detected MgII absorption lines at z=3.54, which show a large variance of column densities (~ 0.3 dex) and velocities (~ 10 km/s) between the sightlines A and B with a projected separation of only 8.4h_{70}^{-1} pc at the redshift. This is the smallest spatial structure of the high-z gas clouds ever detected after Rauch et al. found a 20-pc …
