Inhomogeneous matter distribution and supernovae

This work investigates a simple inhomogeneous cosmological model within the Lema[Formula: see text]tre–Tolman–Bondi (LTB) metric. The mass-scale function of the LTB model is taken to be [Formula: see text] and would correspond to a fractal distribution for [Formula: see text]. The luminosity distance for this model is computed and then compared to supernovae (SNe) data. Unlike LTB models which have, in the most general case, two free functions, our model has only two free parameters as the flat Standard Model of cosmology. The best-fit obtained is a matter distribution with an exponent of [Formula: see text] revealing that SNe data do not favor those fractal models.

COSMOLOGICAL CONSTRAINTS ON THE LOCAL VOID WITH THE UNION SUPERNOVA COMPILATION

A simple inhomogeneous cosmological model with a local void is constrained with the latest Union supernova compilation. To fit the supernova data, a large local void on the scales of 1 Gpc is found, contrary to the small scales of 200 Mpc in the previous finding. A more realistic inhomogeneous cosmological model may be required to fit the supernova data. Alternatively, a clumpy universe with α < 1 can fit the supernova data with reduced local void scales.

A STUDY OF HIGHER DIMENSIONAL INHOMOGENEOUS COSMOLOGICAL MODEL

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 various parameters involved and for dust case. Finally, we examine the asymptotic behaviour of some of these solutions.

INHOMOGENEOUS COSMOLOGICAL MODEL IN LYRA GEOMETRY

Exact solutions are obtained for an inhomogeneous cosmological model in normal gauge for Lyra's geometry. Some properties of the model have also been discussed.

Theoretical and Observational Implications of a Super-Horizon-Scale Inhomogeneous Cosmological Model

We discuss the theoretical and observational implications of an inhomogeneous cosmological model consisting of three regions: the inner low-density homogeneous region, the self-similar (or partially similar) inhomogeneous region and the outer nearly flat homogeneous region. When we assume Einstein's gravitational theory without cosmological constant, the standard inflation theory, and the observational fact of local low density around us, this model is found to be reasonable. The boundary between the inner region and the self-similar region is assumed to be in a spherical shell corresponding to the epoch of redshift z = 1.5–2.0, when the numbers of QSOs and Ly α clouds changed rapidly.