Related papers: Is B1422+231 a Golden Lens?

Galaxies located in the environment or on the line of sight towards gravitational lenses can significantly affect lensing observables, and can lead to systematic errors on the measurement of $H_0$ from the time-delay technique. We present…

The extreme bolometric luminosity of IRAS F10214+4724, and in particular the huge mass in molecular gas inferred from the CO line fluxes have led to suggestions that this is a giant galaxy in the process of formation. An arc-like structure…

Longtime monitoring of gravitational lens systems is often done using telescopes and recording equipment with modest resolution. Still, it would be interesting to get as much information as possible from the measured lightcurves. From high…

We analyse new optical observations of the gravitational lens system SDSS J1515+1511. These include a 2.6-year photometric monitoring with the Liverpool Telescope (LT) in the $r$ band, as well as a spectroscopic follow-up with the LT and…

We report the discovery of two new gravitationally lensed quasars, WFI J2026-4536 and WFI J2033-4723, at respective source redshifts of z=2.23 and z=1.66. Both systems are quadruply imaged and have similar PG1115-like image configurations.…

We report the discovery of a cluster of galaxies in the field of UM425, a pair of quasars separated by 6.5arcsec. Based on this finding, we revisit the long-standing question of whether this quasar pair is a binary quasar or a…

Gravitationally lensed Type Ia supernovae are an emerging probe with great potential for constraining dark energy, spatial curvature, and the Hubble constant. The multiple images and their time delayed and magnified fluxes may be…

SDSS J2222+2745, at z = 0.489, is one of the few currently known lens clusters with multiple images of a background (z = 2.801) quasar with measured time delays. We combine imaging from the Hubble Space Telescope (HST) with recent Multi…

We present a high-resolution spectrum of the high redshift, lensed quasar Q1208+1101, obtained with the echellette spectrograph on the Multiple Mirror Telescope. We examine the new and published spectra and provide an updated list of…

We have discovered a new gravitational lens in the Cosmic Lens All-Sky Survey (CLASS). B2045+265 is a four-image system with a maximum separation of 1.9 arcsec. A fifth radio component is detected, but its radio spectrum and its positional…

Gravitational lensing is a powerful tool for the study of the distribution of dark matter in the Universe. The cold-dark-matter model of the formation of large-scale structures predicts the existence of quasars gravitationally lensed by…

A method for determining the time delays in gravitationally lensed quasars is proposed, which offers a simple and transparent procedure to mitigate the effects of microlensing. The method is based on fundamental properties of representation…

Measurement of the time delay between multiple images of a gravitational lens system is potentially an accurate method of determining the Hubble constant over cosmological distances. One of the most promising candidates for an application…

Infrared images of the Q 0957+561 gravitational lens obtained with the Hubble Space Telescope show two large (\sim 5 arcsec) lensed images of the z_s=1.41 quasar host galaxy. Parts of the host galaxy are doubly-imaged like the quasar, while…

We present optical R-band light curves of the gravitationally lensed quasar SBS1520+530 derived from data obtained at the Nordic Optical Telescope. A time delay of 130+/-3 days (1 sigma) is determined from the light curves. In addition,…

Time delay measurements have recently been reported for the lensed quasar PG 1115+080. These measurements can be used to derive Ho, but only if we can constrain the lensing potential. We have applied a recently developed deconvolution…

(abridged) Aims: RXS J113155.4-123155 (z=0.66) is a quadruply imaged lensed quasar with a resolved Einstein Ring. The goal of this paper is to provide a full characterization of this system, and more particularly accurate astrometry and…

We have created 0.3--10 keV, 13 year, unabsorbed luminosity lightcurves for 528 X-ray sources in the central 20' of M31. We have 174 Chandra observations spaced at ~1 month intervals thanks to our transient monitoring program, deeper…

Among known strongly lensed quasar systems, ~25% have gravitational potentials sufficiently flat (and sources sufficiently well aligned) to produce four images rather than two. The projected flattening of the lensing galaxy and tides from…

The mini Broad Absorption Line (BAL) quasar RX J0911.4+0551 was observed with the Advanced CCD Imaging Spectrometer (ACIS) of the Chandra X-ray Observatory for ~ 29 ks as part of a gravitational lens (GL) survey aimed at measuring…