Identifying Anomalies in Gravitational Lens Time Delays

Congdon, Arthur B.; Keeton, Charles R.; Nordgren, C. Erik

doi:10.1088/0004-637x/709/2/552

Cited by 22 publications

(28 citation statements)

References 78 publications

(137 reference statements)

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“…Its amplitude is consistent with a perturbation produced by a dark matter substructure located near the Einstein radius of the lens (Chen et al 2007). Problems encountered in reproducing the flux ratios, which are also affected by significant microlensing , and problems to reproduce the preliminary time delays (Morgan et al 2006;Keeton & Moustakas 2009;Congdon et al 2010) strongly support this interpretation. Astrometric anomalies possibly caused by substructures might also be present in other systems such as WFI 2026-4536 and B2045+265, for which the best simple model predicts a strong tilt between the mass and the light distributions.…”

Section: Astrometric Anomaliesmentioning

confidence: 56%

COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses

Sluse

Chantry

Magain

et al. 2012

A&A

121

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Gravitationally lensed quasars can be used as powerful cosmological and astrophysical probes. We can (i) infer the Hubble constant H 0 based on the so-called time-delay technique, (ii) unveil substructures along the line-of-sight toward distant galaxies, and (iii) compare the shape and the slope of baryons and dark matter distributions in the inner regions of galaxies. To reach these goals, we need highaccuracy astrometry of the quasar images relative to the lensing galaxy and morphology measurements of the lens. In this work, we first present new astrometry for 11 lenses with measured time delays, namely, JVAS B0218+357, SBS 0909+532, RX J0911.4+0551, FBQS J0951+2635, HE 1104-1805, PG 1115+080, JVAS B1422+231, SBS 1520+530, CLASS B1600+434, CLASS B1608+656, and HE 2149-2745. These measurements proceed from the use of the Magain-Courbin-Sohy (MCS) deconvolution algorithm applied in an iterative way (ISMCS) to near-IR HST images. We obtain a typical astrometric accuracy of about 1-2.5 mas and an accurate shape measurement of the lens galaxy. Second, we combined these measurements with those of 14 other lensing systems, mostly from the COSMOGRAIL set of targets, to present new mass models of these lenses. The modeling of these 25 gravitational lenses led to the following results: 1) in four double-image quasars (HE0047-1746, J1226-006, SBS 1520+530, and HE 2149-2745), we show that the influence of the lens environment on the time delay can easily be quantified and modeled, hence putting these lenses with high priority for time-delay determination; 2) for quadruple-image quasars, the difficulty often encountered in reproducing the image positions to milli-arcsec accuracy (astrometric anomaly problem) is overcome by explicitly including the nearest visible galaxy/satellite in the lens model. However, one anomalous system (RXS J1131-1231) does not show any luminous perturber in its vicinity, and three others (WFI 2026-4536, WFI 2033, and B2045+265) have problematic modeling. These four systems are the best candidates for a pertubation by a dark matter substructure along the line-of-sight; 3) we revisit the correlation between the position angle (PA) and ellipticity of the light and of the mass distribution in lensing galaxies. As in previous studies, we find a significant correlation between the PA of the light and of the mass distributions. However, in contrast with these same studies, we find that the ellipticity of the light and of the mass also correlate well, suggesting that the overall spatial distribution of matter is not very different from the baryon distribution in the inner ∼5 kpc of lensing galaxies. This offers a new test for high-resolution hydrodynamical simulations.

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Section: Astrometric Anomaliesmentioning

confidence: 56%

COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses

Sluse

Chantry

Magain

et al. 2012

A&A

121

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“…Thus, the presence of scalar charge helps increase the total magnification. This would provide a modest increase in the likelihood of observing lensing by SgrA Ã (see [27] and references therein).…”

Section: Computations and Resultsmentioning

confidence: 99%

Time delay and magnification centroid due to gravitational lensing by black holes and naked singularities

2008

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We model the massive dark object at the center of the Galaxy as a Schwarzschild black hole as well as Janis-Newman-Winicour naked singularities, characterized by the mass and scalar charge parameters, and study gravitational lensing (particularly time delay, magnification centroid, and total magnification) by them. We find that the lensing features are qualitatively similar (though quantitatively different) for Schwarzschild black holes, weakly naked, and marginally strongly naked singularities. However, the lensing characteristics of strongly naked singularities are qualitatively very different from those due to Schwarzschild black holes. The images produced by Schwarzschild black hole lenses and weakly naked and marginally strongly naked singularity lenses always have positive time delays. On the other hand, strongly naked singularity lenses can give rise to images with positive, zero, or negative time delays. In particular, for a large angular source position the direct image (the outermost image on the same side as the source) due to strongly naked singularity lensing always has a negative time delay. We also found that the scalar field decreases the time delay and increases the total magnification of images; this result could have important implications for cosmology. As the Janis-Newman-Winicour metric also describes the exterior gravitational field of a scalar star, naked singularities as well as scalar star lenses, if these exist in nature, will serve as more efficient cosmic telescopes than regular gravitational lenses.

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“…Secondly, time‐variable sources allow us to measure time delays between multiple images; these time delays contain rich information on the lens potentials as well as cosmology (e.g. Witt, Mao & Keeton 2000; Kochanek 2002; Saha & Williams 2003; Schechter 2005; Oguri 2007a; Congdon, Keeton & Nordgren 2008; Keeton & Moustakas 2009; Congdon, Keeton & Nordgren 2010; Keeton 2010).…”

Section: Introductionmentioning

confidence: 99%

Gravitationally lensed quasars and supernovae in future wide-field optical imaging surveys

Oguri

Marshall

2010

Monthly Notices of the Royal Astronomical Society

362

303

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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 surveys should detect several thousand lensed quasars. In particular, the Large Synoptic Survey Telescope (LSST) should find more than some 8000 lensed quasars, some 3000 of which will have well‐measured time delays. The LSST should also find some 130 lensed supernovae during the 10‐yr survey duration, which is compared with ∼15 lensed supernovae predicted to be found by a deep, space‐based supernova survey done by the Joint Dark Energy Mission. We compute the quad fraction in each survey, predicting it to be ∼15 per cent for the lensed quasars and ∼30 per cent for the lensed supernovae. Generating a mock catalogue of around 1500 well‐observed double‐image lenses, as could be derived from the LSST survey, we compute the available precision on the Hubble constant and the dark energy equation parameters for the time‐delay distance experiment (assuming priors from Planck): the predicted marginalized 68 per cent confidence intervals are σ(w0) = 0.15, σ(wa) = 0.41 and σ(h) = 0.017. While this is encouraging in the sense that these uncertainties are only 50 per cent larger than those predicted for a space‐based Type Ia supernova sample, we show how the dark energy figure of merit degrades with decreasing knowledge of the lens mass distribution.

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Identifying Anomalies in Gravitational Lens Time Delays

Cited by 22 publications

References 78 publications

COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses

COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses

Time delay and magnification centroid due to gravitational lensing by black holes and naked singularities

Gravitationally lensed quasars and supernovae in future wide-field optical imaging surveys

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