Related papers: Calculating Observables in Inhomogeneous Cosmologi…
In a flat, k=0 cosmology with galaxies that approximate singular isothermal spheres, gravitational lens image separations should be uncorrelated with source redshift. But in an open k=-1 cosmology such gravitational lens image separations…
Recent analyses of large-scale structure and redshift surveys have reported significant dipolar anisotropies in the local Universe that are not straightforwardly attributable to a global kinematic boost. When interpreted within standard…
The exploration of the redshift drift, a direct measurement of cosmological expansion, is expected to take several decades of observation with stable, sensitive instruments. We introduced a new method to probe cosmology which bypasses the…
This thesis concerns the compatibility of inhomogeneous cosmologies with our present understanding of the universe. It is a problem of some interest to find the class of all relativistic cosmological models which are capable of providing a…
Using a multiple-lens plane algorithm, we study light propagation in inhomogeneous universes, for 43 different COBE-normalized Cold Dark Matter models, with various values of the density parameter Omega_0, cosmological constant lambda_0,…
We define an optimal basis system into which cosmological observables can be decomposed. The basis system can be optimised for a specific cosmological model or for an ensemble of models, even if based on drastically different physical…
Lensing in a spherically symmetric and static spacetime is considered, based on the lightlike geodesic equation without approximations. After fixing two radius values r_O and r_S, lensing for an observation event somewhere at r_O and static…
In [1], it is established that a convergent observer with an infinite gain margin can be designed for a given nonlinear system when a Riemannian metric showing that the system is differentially detectable (i.e., the Lie derivative of the…
We analyze two different algorithms for constructing weakly inhomogeneous models for the low-redshift Universe, in order to provide a tool for testing the geodesic dynamics, within the sphere of validity for the Universe acceleration. We…
We present a general gauge invariant formalism for defining cosmological averages that are relevant for observations based on light-like signals. Such averages involve either null hypersurfaces corresponding to a family of past light-cones…
This work discusses the possible empirical verification of the geometrical concept of homogeneity of the standard relativistic cosmology considering its various definitions of distance. We study the physical consequences of the distinction…
In this thesis, I present three projects I carried out during m PhD. In the first project, I introduce Conformal Transformations and the Galaxy Number County. I explicitly show that the Galaxy Number Counts is invariant under Conformal…
We study the impact of cosmic inhomogeneities on the interpretation of observations. We build an inhomogeneous universe model without dark energy that can confront supernova data and yet is reasonably well compatible with the Copernican…
In this paper we present a class of exact inhomogeneous solutions to Einstein's equations for higher dimensional Szekeres metric with perfect fluid and a cosmological constant. We also show particular solutions depending on the choices of…
We consider a cosmology in which a spherically symmetric large scale inhomogeneous enhancement or a void are described by an inhomogeneous metric and Einstein's gravitational equations. For a flat matter dominated universe the inhomogeneous…
We use astrophysical data to shed light on fundamental physics by constraining parametrized theoretical cosmological and gravitational models. Gravitational parameters are those constants that parametrize possible departures from Einstein's…
We examine the properties of a recently proposed observationally viable alternative to homogeneous cosmology with smooth dark energy, the timescape cosmology. In the timescape model cosmic acceleration is realized as an apparent effect…
We investigate the properties of cosmological distances in locally inhomogeneous universes with pressureless matter and dark energy (quintessence), with constant equation of state. We give exact solutions for angular diameter distances in…
At a time when galaxy surveys and other observations are reaching unprecedented sky coverage and precision it seems timely to investigate the effects of general relativistic nonlinear dynamics on the growth of structures and on…
We build an exact inhomogeneous universe composed of a central flat Friedmann zone up to a small redshift $z_1$, a thick shell made of anisotropic matter, an hyperbolic Friedmann metric up to the scale where dimming galaxies are observed…