Relativistic thermodynamics of radiating stars.

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.