Collapsing shear-free perfect fluid spheres with heat flow

TL;DR

This paper presents a simplified formalism for analyzing collapsing shear-free perfect fluid spheres with heat flow, deriving general solutions and exploring conditions leading to black holes or naked singularities.

Contribution

It introduces a compact formalism that simplifies key conditions and provides a unified approach to static and dynamic models of collapsing fluid spheres.

Findings

Derived general solutions for shear-free perfect fluid collapse.

Presented a formalism simplifying isotropy and junction conditions.

Explored conditions leading to black hole or naked singularity formation.

Abstract

A global view is given upon the study of collapsing shear-free perfect fluid spheres with heat flow. We apply a compact formalism, which simplifies the isotropy condition and the condition for conformal flatness. This formalism also presents the simplest possible version of the main junction condition, demonstrated explicitly for conformally flat and geodesic solutions. It gives the right functions to disentangle this condition into well known differential equations like those of Abel, Riccati, Bernoulli and the linear one. It yields an alternative derivation of the general solution with functionally dependent metric components. We bring together the results for static and time- dependent models to describe six generating functions of the general solution to the isotropy equation. Their common features and relations between them are elucidated. A general formula for separable solutions is given, incorporating collapse to a black hole or to a naked singularity.