Related papers: Weak gravitational lensing
The observed acceleration of the universe, explained through dark energy, could alternatively be explained through a modification of gravity that would also induce modifications in the evolution of cosmological perturbations. We use new…
Gravitational lensing has been identified as a powerful tool to address fundamental problems in astrophysics at different scales, ranging from exoplanet identification to dark energy and dark matter characterization in cosmology. Image…
Gravitational lensing has become one of the most interesting tools to study the mass distribution in the Universe. Since gravitational light deflection is independent of the nature and state of the matter, it is ideally suited to…
The accelerated expansion of the Universe remains one of the central open problems in modern cosmology. While the $\Lambda$CDM model successfully describes a wide range of observations, the physical nature of dark energy is still unknown,…
Variability in gravitationally lensed quasars can be due to intrinsic fluctuations of the quasar or due to ``microlensing'' by compact objects along the line of sight. If disentangled from each other, microlens-induced variability can be…
Ordinary baryonic particles (such as protons and neutrons) account for only one-sixth of the total matter in the Universe. The remainder is a mysterious "dark matter" component, which does not interact via the electromagnetic force and thus…
Only galaxies bright enough and large enough to be unambiguously identified and measured are included in galaxy surveys used to estimate cosmic shear. We demonstrate that because gravitational lensing can scatter galaxies across the…
The analysis of strong lensing images usually involves an external convergence and shear, which are meant to model the effect of perturbations along the line of sight, on top of the main lens. Such a description of line-of-sight…
As gravitational lensing measurements become increasingly precise, it becomes necessary to include ever higher order effects in the theoretical calculations. Here we show how the difference between the shear and the reduced shear manifest…
This thesis contributes to the field of gravitational lensing (GL) and observational cosmology. We discuss the use of gravitational lensing as a tool in search of exotic objects in the Universe. In the next chapter the concordance of an…
We investigate the effects of weak gravitational lensing in the standard Cold Dark Matter cosmology, using an algorithm which evaluates the shear in three dimensions. The algorithm has the advantage of variable softening for the particles,…
Exotic objects such as the Ellis wormhole are expected to act as gravitational lenses. Much like their nonexotic counterparts, information about these lenses can be found by considering the strong and weak lensing fields they induce. In…
The gravitational lensing effect is one of the most promising tools for cosmology. Indeed it probes directly the total mass distribution in large-scale structures and can as well provide valuable informations on the values of the density…
We present the theory of weak gravitational lensing in cosmologies with generalized gravity, described in the Lagrangian by a generic function depending on the Ricci scalar and a non-minimally coupled scalar field. We work out the…
The basic equations and geometry of gravitational lensing are described, as well as the most important contexts in which it is observed in astronomy: strong lensing, weak lensing and microlensing.
We study the effect of modifications to General Relativity on large scale weak lensing observables. In particular, we consider three modified gravity scenarios: f(R) gravity, the DGP model, and TeVeS theory. Weak lensing is sensitive to the…
Many recent studies have demonstrated that scaling arguments, such as the so-called hierarchical {\em ansatz}, are extremely useful in understanding the statistical properties of weak gravitational lensing. This is especially true on small…
We derive expressions, in terms of "polar shapelets", for the image distortion operations associated with weak gravitational lensing. Shear causes galaxy shapes to become elongated, and is sensitive to the second derivative of the projected…
Weak gravitational lensing of background galaxies by intervening matter directly probes the mass distribution in the universe. This distribution, and its evolution at late times, is sensitive to both the dark energy, a negative pressure…
In this thesis, we scrutinize the literature to trace the evolution of the concepts surrounding the weak cosmic censorship conjecture and the attempts to prove or disprove it. We discuss its development over the years, its conceptual…