Inhomogeneous imperfect fluid spherical models without Big-Bang singularity

TL;DR

This paper introduces a new family of spherically symmetric, non-singular cosmological models filled with imperfect fluid and heat flow, which evolve towards perfect fluid conditions over time, expanding the class of singularity-free models beyond cylindrical symmetry.

Contribution

It presents the first known spherically symmetric, non-singular cosmological models with imperfect fluids and heat flow, satisfying energy conditions, and demonstrating a transition to perfect fluid behavior.

Findings

Models are free of Big Bang singularity.

Anisotropy and heat flux diminish over time.

Multiple free functions allow tailored non-singular solutions.

Abstract

So far all known singularity-free cosmological models are cylindrically symmetric. Here we present a new family of spherically symmetric non-singular models filled with imperfect fluid and radial heat flow, and satisfying the weak and strong energy conditions. For large $t$ anisotropy in pressure and heat flux tend to vanish leading to a perfect fluid. There is a free function of time in the model, which can be suitably chosen for non-singular behaviour and there exist multiplicity of such choices.