Transport processes in the gravitational collapse of an anisotropic fluid

Abstract

In this paper we introduce a new method to study the influence of thermal conduction and viscous processes in anisotropic gravitational collapse. To this end we employ the HJR method to solve the Einstein equations. The Maxwell-Cattaneo type transport equations are used to find the temperature and bulk and shear viscous pressures. Under some conditions Maxwell-Cattaneo transport equations comply with relativistic causality. Thus, it is advisable to use them instead of Eckart transport equations. In the inner layers of the star the temperature ceases to be sensitive to the boundary condition. This behavior, which can be explained in terms of the Eddington approximation, allows us to find the thickness of the neutrinosphere. The dynamics of collapsing dense stars is deeply influenced by the neutrino emission/absorption processes. These cool the star and drive it to a new equilibrium state. Therefore, the calculation of transport coefficients is based on these processes.

Dynamics of dissipative gravitational collapse

“…Under these conditions both κ and T could be sufficiently large as to imply a substantial increase of α. Indeed, the values suggested in [35] , in c.g.s units and Kelvin ) lead to α ≈ 1. The obvious consequence of which would be to enhance the efficiency of whatever expansion mechanism, of the central core, at place, because of the decreasing of the inertial mass density and the gravitational force term.…”

Thermal Evolution of a Radiating Anisotropic Star With Shear

“…This special case can only give a reasonable model for a limited range of temperature. Following Martínez 5 , we assume that the velocity of thermal dissipative signals is comparable to the adiabatic sound speed which is satisfied if the relaxation time is proportional to the collision time:…”

“…For a physically reasonable model, we use the thermodynamic coefficients for radiative transfer outlined in Martínez 5 . We consider the situation where energy is carried away from the stellar core by massless particles that are thermally generated with energies of the order of kT .…”

Behaviour of charged collapsing fluids after hydrostatic equilibrium in $$R^n$$ R n gravity

“…For a very small value of the relaxation time at present time, we may speculate that β may increase substantially in a pre-supernova event. In fact, at the last stages of a massive star evolution, the decrease of inertial densities would prevent the propagation of photons and neutrinos [22]. (ii) If β → 0, then there is no effect on the inertial mass density and gravitational force.…”