Transit universe with time varying $G$ and decaying $\Lambda$

TL;DR

This paper proposes a cosmological model with a time-varying gravitational constant and cosmological term, describing a universe transitioning from deceleration to acceleration, consistent with supernova observations.

Contribution

It introduces a new transit universe model with variable G and Lambda, solving Einstein's equations with a specific scale factor form and analyzing its features.

Findings

Lambda(t) is positive and decreases over time.

Model aligns with supernova Ia observational data.

Describes universe transitioning from deceleration to acceleration.

Abstract

We present the model of transit universe from early deceleration phase to current acceleration phase under the framework of general relativity in presence of gravitational coupling $G(t)$ and cosmological terms $\Lambda(t)$. The Einstein's field equations have been solved by considering time dependent deceleration parameter (DP) which renders the scale factor $a = (t^{n}e^{kt})^{\frac{1}{m}}$ where $m$, $n$ and $k$ are positive constants. The cosmological term $(\Lambda(t))$ is found to be positive and a decreasing function of time which supports the result obtained from supernovae Ia observations. The geometrical and kinematical features of the model are examined in detail.