The milli-arcsecond images of Q0957 + 561

Gorenstein, M. V.; Shapiro, I. I.; Rogers, A. E. E.; Cohen, N. L.; Corey, B. E.; Porcas, R. W.; Falco, E.; Bonometti, R. J.; Preston, R. A.; Rius, A.; Whitney, A. R.

doi:10.1086/162712

Cited by 34 publications

(21 citation statements)

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“…On the other hand, resolved sources can measure the tensor relative magnification M 0 M À1 . This point was made by Gorenstein et al (1984) and their equation (2) is essentially our equation (3). They and later authors used the idea to incorporate tensor magnification in models of B0957+561 (Garrett et al 1994;Grogin & Narayan 1996) and B1422+231 (Raychaudhury et al 2003).…”

Section: The Galaxy Lens Mg J0414+053mentioning

confidence: 99%

Meso‐Structure in Three Strong‐lensing Systems

Saha

Williams

Ferreras

2007

ApJ

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We map substructure in three strong-lensing systems having particularly good image data: the galaxy lens MG J0414+053 and the clusters SDSS J1004+411 and ACO 1689. Our method is to first reconstruct the lens as a pixelated mass map and then subtract off the symmetric part (in the galaxy case) or a projected Navarro-Frenk-White profile (for the cluster lenses). In all three systems we find extended irregular structures, or meso-structures, having of order 10% of the total mass. In J0414+053, the meso-structure suggests a tidal tail connecting the main lens with a nearby galaxy; however, this interpretation is tentative. In the clusters, the identification of meso-structure is more secure, especially in ACO 1689, where two independent sets of lensed images imply very similar meso-structure. In all three cases, the meso-structures are correlated with galaxies but much more extended and massive than the stellar components of single galaxies. Such extended structures cannot plausibly persist in such high-density regions without being mixed; the crossing times are too short. The meso-structures therefore appear to be merging or otherwise dynamically evolving systems.

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Section: The Galaxy Lens Mg J0414+053mentioning

confidence: 99%

Meso‐Structure in Three Strong‐lensing Systems

Saha

Williams

Ferreras

2007

ApJ

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“…The radio maps of both components showed the presence of radio cores and ∼0. 1 jets (Porcas et al 1981;Gorenstein et al 1984Gorenstein et al , 1988Garrett et al 1994;Haarsma et al 2001). Hutchings (2003) reported evidence for EUV (∼1100 Å) activity along the radio jets.…”

Section: Introductionmentioning

confidence: 99%

Structure function of the UV variability of Q0957+561

Goicoechea

Shalyapin

Gil-Merino

et al. 2008

A&A

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We present a detailed structure function analysis of the UV variability of Q0957+561. From optical observations in the 2005−2007 seasons, we constructed normalized structure functions of the quasar luminosity at restframe wavelengths λ ∼ 2100 Å and λ ∼ 2600 Å. Old optical records (1995−1996 seasons) also allow the structure function to be obtained at λ ∼ 2100 Å, but 10 years ago in the observer's frame. These three structure functions are then compared to predictions of both simple and relatively sophisticated (incorporating two independent variable components) Poissonian models. We do not find clear evidence of a chromatic mechanism of variability. From the recent data, ∼100-d time-symmetric and ∼170-d time-asymmetric flares are produced at both restframe wavelengths. Taking into account measurements of time delays and the existence of an EUV/radio jet, reverberation is probably the main mechanism of variability. Thus, two types of EUV/X-ray fluctuations would be generated within or close to the jet and later reprocessed by the disc gas in the two emission rings, at λ ∼ 2100 Å and λ ∼ 2600 Å. The ∼100-d time-symmetric shots are also responsible for most of the ∼2100 Å variability detected in the old experiment (10 years ago). However, there is no evidence of asymmetric shots in the old UV variability. If reverberation is the involved mechanism of variability, this could mean an intermittent production of high-energy asymmetric fluctuations. The old records are also consistent with the presence of very short-lifetime (∼10 d) symmetric flares, which may represent additional evidence of time evolution. Despite these exciting findings, we cannot rule out the possibility of unfortunate gaps in the old light curves (or a relatively short monitoring period) and very short-timescale systematic noise. We also discuss the quasar structure that emerges from the variability scenario.

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“…Thus far, three cases of resolved multiple images of background galaxies caused by a galaxy cluster as lens have been observed: five multiple images in the galaxy cluster CL0024+17 as found by [59], a giant arc and its counter image in the galaxy cluster RCS2 032727-132623 as discovered by [60], and three images of a spiral galaxy in the galaxy cluster MACS J1149.5+2223 as first detailed in [61]. In the radio bands, some multiple images of QSOs show resolved features like core-jet structures, see e.g., [62] or [63]. Table 2 shows the most common multiple-image configurations, i.e., the relative positions and orientations of multiple images with respect to each other.…”

Section: Observables In Multiple Imagesmentioning

confidence: 87%

“…The work in Ref. [62] already described the possibility to extract the local lens properties contained in A(x) by transforming multiple images onto each other. In [23,47], we realised this idea for unresolved and resolved multiple images that contain at least two non-parallel vectors, as indicated by the black arrows in the figures of Table 1.…”

Section: Local Lens Properties From a Taylor Expansion Around The Cenmentioning

confidence: 99%

A Model-Independent Characterisation of Strong Gravitational Lensing by Observables

Wagner

2019

Universe

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When light from a distant source object, like a galaxy or a supernova, travels towards us, it is deflected by massive objects that lie in its path. When the mass density of the deflecting object exceeds a certain threshold, multiple, highly distorted images of the source are observed. This strong gravitational lensing effect has so far been treated as a model-fitting problem. Using the observed multiple images as constraints yields a self-consistent model of the deflecting mass density and the source object. As several models meet the constraints equally well, we develop a lens characterisation that separates data-based information from model assumptions. The observed multiple images allow us to determine local properties of the deflecting mass distribution on any mass scale from one simple set of equations. Their solution is unique and free of model-dependent degeneracies. The reconstruction of source objects can be performed completely model-independently, enabling us to study galaxy evolution without a lens-model bias. Our approach reduces the lens and source description to its data-based evidence that all models agree upon, simplifies an automated treatment of large datasets, and allows for an extrapolation to a global description resembling model-based descriptions.

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The milli-arcsecond images of Q0957 + 561

Cited by 34 publications

References 0 publications

Meso‐Structure in Three Strong‐lensing Systems

Meso‐Structure in Three Strong‐lensing Systems

Structure function of the UV variability of Q0957+561

A Model-Independent Characterisation of Strong Gravitational Lensing by Observables

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