Accelerating Universe from an Evolving Lambda in Higher Dimension

TL;DR

This paper presents exact solutions for a five-dimensional inhomogeneous universe with a variable cosmological constant, demonstrating how extra dimensions and anisotropy influence cosmic acceleration and key astrophysical parameters.

Contribution

It introduces a novel five-dimensional inhomogeneous cosmological model with a dynamic Lambda, showing how it can produce late-time acceleration and affect universe age and flip timing.

Findings

Achieves acceleration through adjustable integration constants.

Finds that extra dimensions delay the cosmic flip.

Models yield a larger universe age than many quintessence models.

Abstract

We find exact solutions in five dimensional inhomogeneous matter dominated model with a varying cosmological constant. Adjusting arbitrary constants of integration one can also achieve acceleration in our model. Aside from an initial singularity our spacetime is regular everywhere including the centre of the inhomogeneous distribution. We also study the analogous homogeneous universe in (4+d) dimensions. Here an initially decelerating model is found to give late acceleration in conformity with the current observational demands. We also find that both anisotropy and number of dimensions have a role to play in determining the time of flip, in fact the flip is delayed in multidimensional models. Some astrophysical parameters like the age, luminosity distance etc are also calculated and the influence of extra dimensions is briefly discussed. Interestingly our model yields a larger age of the universe compared to many other quintessential models.