Causal thermodynamics of a gravitational collapse model for an anisotropic fluid with dissipative flows

TL;DR

This paper models the gravitational collapse of an anisotropic, dissipative star using thermodynamics, demonstrating a physically consistent temperature profile and evolution toward black hole formation.

Contribution

It introduces a detailed hydrodynamic and thermodynamic model of anisotropic dissipative collapse, including viscous effects and heat flow, with analysis of temperature and luminosity evolution.

Findings

Model satisfies all energy conditions during collapse

Temperature profile aligns with extended irreversible thermodynamics

Provides a physically reasonable evolution toward black hole formation

Abstract

This paper presents a hydrodynamic and thermodynamic treatment of a radiant star model that undergoes a dissipative gravitational collapse, from a certain initial configuration until it becomes a black hole. The collapsing star consists of a locally anisotropic non-perfect fluid, where we explore the consequences of including viscous pressures, both shear and bulk viscosities, as well as radial heat flow. We analyze the temporal evolution of the heat flux, mass function, luminosity perceived by an observer at infinity and the effective surface temperature. It is shown that this simple exact model, satisfying all the energy conditions throughout the interior region of the star and during all the collapse process, provides a physically reasonable behavior for the temperature profile in the context of the extended irreversible thermodynamics.