Singularity Theory and Gravitational Lensing

Petters, Arlie O.; Levine, Harold; Wambsganß, J.

doi:10.1007/978-1-4612-0145-8

Cited by 260 publications

(450 citation statements)

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“…(28) in the approximation of weak and stationary fields. As a fundamental consequence, the lensing deflection angle will be given by the same formal expression found in general relativity (Schneider et al 1992;Petters et al 2001)…”

Section: Gravitational Lensingmentioning

confidence: 82%

Testing an exactf(R)-gravity model at Galactic and local scales

Capozziello

Piedipalumbo

Rubano

et al. 2009

A&A

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Context. The weak field limit for a pointlike source of a f (R) ∝ R 3/2 -gravity model is studied. Aims. We aim to show the viability of such a model as a valid alternative to GR + dark matter at Galactic and local scales. Methods. Without considering dark matter, within the weak field approximation, we find general exact solutions for gravity with standard matter, and apply them to some astrophysical scales, recovering the consistency of the same f (R)-gravity model with cosmological results.Results. In particular, we show that it is possible to obtain flat rotation curves for galaxies, and consistency with Solar System tests, as in the so-called "Chameleon approach". In fact, the peripheral velocity v ∞ is shown to be expressed as v ∞ = λ √ M, so that the Tully-Fisher relation is recovered. Conclusions. The results point out the possibility of achieving alternative theories of gravity in which exotic ingredients like dark matter and dark energy are not necessary, while their coarse-grained astrophysical and cosmological effects can be related to a geometric origin.

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Section: Gravitational Lensingmentioning

confidence: 82%

Testing an exactf(R)-gravity model at Galactic and local scales

Capozziello

Piedipalumbo

Rubano

et al. 2009

A&A

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“…For an image pair in a fold configuration produced by any smooth lens potential, there is also a generic magnification relation, namely the 'fold relation' (Blandford & Narayan 1986;Schneider & Weiss 1992;Schneider, Ehlers & Falco 1992;Petters, Levine & Wambsganss 2001). In this paper, we take the form as in Keeton et al (2005):…”

Section: The Fold Relationmentioning

confidence: 99%

How well can cold dark matter substructures account for the observed radio flux-ratio anomalies

Xu¹,

Sluse²,

Gao³

et al. 2015

Monthly Notices of the Royal Astronomical Society

118

148

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Discrepancies between the observed and model-predicted radio flux ratios are seen in a number of quadruply-lensed quasars. The most favoured interpretation of these anomalies is that CDM substructures present in lensing galaxies perturb the lens potentials and alter image magnifications and thus flux ratios. So far no consensus has emerged regarding whether or not the predicted CDM substructure abundance fully accounts for the lensing flux anomaly observations. Accurate modelling relies on a realistic lens sample in terms of both the lens environment and internal structures and substructures. In this paper we construct samples of generalised and specific lens potentials, to which we add (rescaled) subhalo populations from the galaxy-scale Aquarius and the cluster-scale Phoenix simulation suites. We further investigate the lensing effects from subhalos of masses several orders of magnitude below the simulation resolution limit. The resulting flux ratio distributions are compared to the currently best available sample of radio lenses. The observed anomalies in B0128+437, B0712+472 and B1555+375 are more likely to be caused by propagation effects or oversimplified/improper lens modelling, signs of which are already seen in the data. Among the quadruple systems that have closely located image triplets/pairs, the anomalous flux ratios of MG0414+0534 can be reproduced by adding CDM subhalos to its macroscopic lens potential, with a probability of 5% − 20%; for B0712+472, B1422+231, B1555+375 and B2045+265, these probabilities are only of a few percent. We hence find that CDM substructures are unlikely to be the whole reason for radio flux anomalies. We discuss other possible effects that might also be at work.

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“…Fortunately, a different mass tracer may be available for a subset of ETGs at intermediate redshift. Actually, gravitational lensing gives a strong constraint on the projected mass within the so called Einstein radius (Schneider et al 1992;Petters et al 2001). It is worth stressing that such an observational quantity is fully model independent although a galaxy model has to be assumed to extrapolate the results to other radii.…”

Section: Introductionmentioning

confidence: 99%

The global mass-to-light ratio of SLACS lenses

Cardone

Tortora

Molinaro

et al. 2009

A&A

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Aims. The dark matter content of early-type galaxies (ETGs) is a hotly debated topic with contrasting results arguing in favour of or against the presence of significant dark mass within the effective radius and the change with luminosity and mass. To address this question, we investigate here the global mass-to-light ratio Υ(r) = M(r)/L(r) of a sample of 21 lenses observed within the Sloan Lens ACS (SLACS) survey. Methods. We follow the usual approach of the galaxy as a two component systems, but we use a phenomenological ansatz for Υ(r), proposed by some of us, that is able to smoothly interpolate between constant M/L models and a wide class of dark matter haloes. The resulting galaxy model is then fitted to the data on the Einstein radius and aperture velocity dispersion. Results. Our phenomenological model turns out to agree with the data suggesting the presence of massive dark matter haloes to explain the lensing and dynamics properties of the SLACS lenses. According to the values of the dark matter mass fraction, we argue that the halo may play a significant role in the inner regions probed by the data, but such a conclusion strongly depends on the adopted initial mass function of the stellar population. Finally, we find that the dark matter mass fraction within R eff scales with both the total luminosity and stellar mass in such a way that more luminous (and hence more massive) galaxies have a greater dark matter content.

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Singularity Theory and Gravitational Lensing

Abstract: Singularity theory and gravitationallensing / Adie o. Petters, Harold Levine, Ioachim Wambsganss. p. cm.-(Progress in mathematical physics ; v 21) Includes bibliographical references and indexes.

Cited by 260 publications

References 0 publications

Testing an exactf(R)-gravity model at Galactic and local scales

Testing an exactf(R)-gravity model at Galactic and local scales

How well can cold dark matter substructures account for the observed radio flux-ratio anomalies

The global mass-to-light ratio of SLACS lenses

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