COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses

Chantry, Virginie; Sluse, Dominique; Magain, Pierre

doi:10.1051/0004-6361/200912971

Cited by 37 publications

(65 citation statements)

References 66 publications

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“…For both doubles and quads, we accounted for the lens environment with an external shear term γ. We used the same modeling technique as in Chantry et al (2010) with slightly different observational constraints for the quads. In particular, we constrained the model with the relative astrometry of the lensed images and lensing galaxy, and with the flux ratio of the lensed images.…”

Section: Lens Modeling and Intrinsic Luminositiesmentioning

confidence: 99%

“…(1) Wisotzki et al (2004); (2) Fadely & Keeton (2011); (3) Courbin et al (2011); (4) Schechter et al (1998); (5) Oguri et al (2004); (6) Morgan et al (2004); (7) Vuissoz et al (2008); (8) CASTLES; (9) Chantry et al (2010); (10) Sluse et al (2012); (11) Lehár et al (2000); (12) Inada et al (2005); (13) Sluse et al (2008b); (14) Falco et al (1999); (15) Burud et al (2002); (16) Blackburne et al (2011); (17) Eigenbrod et al (2006a); (18) Sluse et al (2006); (19) Falco et al (1996); (20) Chantry & Magain (2007); (21) MacLeod et al (2009). associated to intrinsic variability and, in a few cases, systematic errors associated to differential extinction and microlensing.…”

Section: Accuracy Of the Intrinsic Flux Ratiosmentioning

confidence: 99%

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Microlensing of the broad line region in 17 lensed quasars

Sluse

Hutsemékers

Courbin

et al. 2012

A&A

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When an image of a strongly lensed quasar is microlensed, the different components of its spectrum are expected to be differentially magnified owing to the different sizes of the corresponding emitting region. Chromatic changes are expected to be observed in the continuum while the emission lines should be deformed as a function of the size, geometry and kinematics of the regions from which they originate. Microlensing of the emission lines has been reported only in a handful of systems so far. In this paper we search for microlensing deformations of the optical spectra of pairs of images in 17 lensed quasars with bolometric luminosities between 10 44.7−47.4 erg/s and black hole masses 10 7.6−9.8 M . This sample is composed of 13 pairs of previously unpublished spectra and four pairs of spectra from literature. Our analysis is based on a simple spectral decomposition technique which allows us to isolate the microlensed fraction of the flux independently of a detailed modeling of the quasar emission lines. Using this technique, we detect microlensing of the continuum in 85% of the systems. Among them, 80% show microlensing of the broad emission lines. Focusing on the most common emission lines in our spectra (C iii] and Mg ii) we detect microlensing of either the blue or the red wing, or of both wings with the same amplitude. This observation implies that the broad line region is not in general spherically symmetric. In addition, the frequent detection of microlensing of the blue and red wings independently but not simultaneously with a different amplitude, does not support existing microlensing simulations of a biconical outflow. Our analysis also provides the intrinsic flux ratio between the lensed images and the magnitude of the microlensing affecting the continuum. These two quantities are particularly relevant for the determination of the fraction of matter in clumpy form in galaxies and for the detection of dark matter substructures via the identification of flux ratio anomalies.

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Section: Lens Modeling and Intrinsic Luminositiesmentioning

confidence: 99%

Section: Accuracy Of the Intrinsic Flux Ratiosmentioning

confidence: 99%

Microlensing of the broad line region in 17 lensed quasars

Sluse

Hutsemékers

Courbin

et al. 2012

A&A

Self Cite

133

184

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“…They have been chosen amongst a larger sample of lenses, which were previously processed in Chantry et al (2010) and Sluse et al (2012). We have chosen to focus on quadruply lensed sources.…”

Section: Datamentioning

confidence: 99%

“…In contrast, the MCS measurements are based on a multi-step procedure where the image is first deconvolved by finding the best PSF and, then, a convolved model is fitted on the image. Motivated by the results of Schechter et al (2014), we re-analysed the data published in Chantry et al (2010) and Sluse et al (2012). We identified two likely sources of systematic errors with those data: on the one hand, the sky background was found to be underestimated, thus attributing too much luminosity to the galaxy.…”

Section: Introductionmentioning

confidence: 99%

Analysis of luminosity distributions and the shape parameters of strong gravitational lensing elliptical galaxies

Biernaux

Magain

Sluse

et al. 2015

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Context. The luminosity profiles of galaxies acting as strong gravitational lenses can be tricky to study. Indeed, strong gravitational lensing images display several lensed components, both point-like and diffuse, around the lensing galaxy. Those objects limit the study of the galaxy luminosity to its inner parts. Therefore, the usual fitting methods perform rather badly on such images. Previous studies of strong lenses luminosity profiles using software such as GALFIT or IMFITFITS and various PSF-determining methods have resulted in somewhat discrepant results. Aims. The present work aims at investigating the causes of those discrepancies, as well as at designing more robust techniques for studying the morphology of early-type lensing galaxies with the ability to subtract a lensed signal from their luminosity profiles. Methods. We design a new method to independently measure each shape parameter, namely, the position angle, ellipticity, and halflight radius of the galaxy. Our half-light radius measurement method is based on an innovative scheme for computing isophotes that is well suited to measuring the morphological properties of gravititational lensing galaxies. Its robustness regarding various specific aspects of gravitational lensing image processing is analysed and tested against GALFIT. It is then applied to a sample of systems from the CASTLES database. Results. Simulations show that, when restricted to small, inner parts of the lensing galaxy, the technique presented here is more trustworthy than GALFIT. It gives more robust results than GALFIT, which shows instabilities regarding the fitting region, the value of the Sérsic index, and the signal-to-noise ratio. It is therefore better suited than GALFIT for gravitational lensing galaxies. It is also able to study lensing galaxies that are not much larger than the PSF. New values for the half-light radius of the objects in our sample are presented and compared to previous works.

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“…To model a lens mass distribution, it is necessary to derive accurate constraints on relative positions of the lensed quasar images and the main lensing galaxy, as well as information on the structure of the galaxy's light (e.g., Lehár et al 2000;Chantry et al 2010;Sluse et al 2012). Other important constraints are the flux ratios between quasar images.…”

Section: Introductionmentioning

confidence: 99%

Deep optical imaging and spectroscopy of the lens system SDSS J1339+1310

Shalyapin

Goicoechea

2014

A&A

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We present deep I-band imaging (NOT-ALFOSC) and spectroscopic (GTC-OSIRIS) observations of the gravitational lens system SDSS J1339+1310. This consists of two images of a lensed quasar, A and B, and a lensing galaxy G between the two quasar images. Our observations led to the following main results: (1) We obtained new accurate positions for B and G (relative to A), as well as structure parameters for the light distribution of G. The new position angle for G is separated by ∼50 • from the previously determined value. (2) The spectrum of G is typical for early-type galaxies, and we measured its redshift (0.609 ± 0.001) for the first time. (3) We determined the flux ratio B/A for the cores of the emission lines in the two quasar spectra. They were used to constrain the macrolens flux ratio M BA and dust extinction parameters. (4) The continuum flux ratio was appropriately corrected to obtain the microlensing magnification ratio of the continuum μ BA . This μ BA indicates that B is amplified (relative to A) by a factor of about 3−5, with larger amplifications at shorter wavelengths. The observed microlensing chromaticity coincides with a sharp drop in the r-band flux of B.(5) We reconstructed the lensing mass from the new observational constraints on the relative astrometry, M BA and the luminous structure of G. We also used the redshift of G to predict the time delay between quasar images (43 ± 5 d, A is leading).

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COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses

Cited by 37 publications

References 66 publications

Microlensing of the broad line region in 17 lensed quasars

Microlensing of the broad line region in 17 lensed quasars

Analysis of luminosity distributions and the shape parameters of strong gravitational lensing elliptical galaxies

Deep optical imaging and spectroscopy of the lens system SDSS J1339+1310

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