# Relativistic thermodynamics of radiating stars.

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## Date

2016

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## Abstract

In this research, on the topic of relativistic thermodynamics of radiating stars, the
following three case studies are investigated:
Gravitational collapse in spacially isotropic coordinates { The nature of a dissipative
collapse process of a spherically symmetric star which has been perturbed into a
dynamical state from an initial static con guration is studied. The collapse process
involves dissipation of energy in the form of a radial heat flux. The perturbation in the
density and pressure profi les are such that the star is always close to hydrostatic equilibrium.
The temperature profi les are studied using a causal heat transport equation.
Radiating collapse in the presence of anisotropic stresses { The effect of anisotropic
stresses are investigated for a collapsing fluid sphere dissipating energy in the form of
a radial flux. The collapse process starts from an initial static sphere described by
the Bowers and Liang solution, and then proceeds until the time of formation of the
horizon. We fi nd that the surface redshift increases as the stellar fluid moves away
from isotropy. The evolution of the temperature pro les is analysed by employing a
causal heat transport equation of the Maxwell-Cattaneo form. Both the Eckart and
causal temperatures are enhanced by anisotropy at each interior point of the stellar
con guration.
The influence of an equation of state during radiative collapse { A linear equation
of state is imposed on a static con guration which undergoes radiative gravitational
collapse. Various values of the equation of state parameter allow descriptions of di erent
matter content from classical stars to dust and also dark energy stars. The physical
parameters are shown to behave in a meaningful and realistic manner.

## Description

Doctor of Philosophy in Mathematics. University of KwaZulu-Natal, Durban 2016.