Non-adiabatic Gravitational Collapse Research Articles

Equilibrium, radial stability and non-adiabatic gravitational collapse of anisotropic neutron stars

In this work we construct families of anisotropic neutron stars for an equation of state compatible with the constraints of the gravitational-wave event GW170817 and for four anisotropy ansatze. Such stars are subjected to a radial perturbation in order to study their stability against radial oscillations and we develop a dynamical model to describe the non-adiabatic gravitational collapse of the unstable anisotropic configurations whose ultimate fate is the formation of a black hole. We find that the standard criterion for radial stability dM/drho _c >0 is not always compatible with the calculation of the oscillation frequencies for some anisotropy ansatze, and each anisotropy parameter is constrained taking into account the recent restriction of maximum mass of neutron stars. We further generalize the TOV equations within a non-adiabatic context and we investigate the dynamical behaviour of the equation of state, heat flux, anisotropy factor and mass function as an unstable anisotropic star collapses. After obtaining the evolution equations we recover, as a static limit, the background equations.

Dynamics of non-adiabatic charged spherical gravitational collapse in [formula omitted] gravity

In current manuscript, we have analyzed the effects of charge on non-adiabatic gravitational collapse dynamics in the framework of f(R,T) gravity utilizing Misner-Sharp approach. The modified field equations of f(R,T) gravity have been evaluated for the spherically symmetric sphere spacetime. The deviation of total energy inside the spacetime of the gravitating compact object has been determined by Misner and Sharp mass function. The key role of some important factors appeared in dynamical equation are investigated in detail. The Bianchi identities affected by electromagnetic field are formulated in f(R,T) gravity to find dynamical equation for compact object. Furthermore, we coupled the causal heat transport equation obtained in the context of Mu¨ller-Israel-Stewart formalism with dynamical equation. To see the more physical results, we have applied a linear model of f(R,T) gravity. Also we have investigated the impacts of matter-curvature coupling constant λ on gravitational forces and inertial mass density. It diminishes the significance of the gravitational force which result to slow down the collapse rate. The proposed applications which are directly related to astrophysical scenarios have been widely discussed.

Non-adiabatic gravitational collapse in f(R,T) gravity with Karmarkar condition for anisotropic fluid

In this paper, we have used the Karmarkar condition to the spherically symmetric non-static radiating star experiencing dissipative gravitational collapse with a heat flux in the framework of [Formula: see text] gravity, (where [Formula: see text] is Ricci scalar which replaces Lagrangian density and [Formula: see text] is the trace of energy–momentum tensor). To obtain the ultimate results of the gravitational field equations in [Formula: see text] scenario, we take a linear form of the function as [Formula: see text]. In this connection, the Karmarkar condition along with boundary condition generates a model of radiating star and enables us to completely indicate the spatial presence of gravitational potentials. Vadiya’s exterior solution across a time-like hypersurface is smoothly matched to the interior solution which allows to study the physical conduct of our model under consideration. Furthermore, we have analyzed the energy conditions of radiating star in [Formula: see text] gravity and analyzed the physical behavior of thermodynamics parameters which provide a detailed discussion of the model. For coupling parameter [Formula: see text], we successfully obtain the standard results of General Relativity.

NON-ADIABATIC GRAVITATIONAL COLLAPSE WITH ANISOTROPIC CORE

The non-adiabatic gravitational collapse of a spherical distribution of matter accompanied by radial heat flux has been studied on the background of a pseudo-spheroidal space–time. The spherical distribution is divided into two regions: a core consisting of anisotropic pressure distribution and an envelope consisting of isotropic pressure distribution. Various aspects of the collapse have been studied using both analytic and numerical methods.

Non-adiabatic gravitational collapse in higher dimensional space-time and its junctions conditions

Junction conditions are studied at the boundary of a higher dimensional spherical distribution containing an outgoing heat flow and radiation flux. Our analysis extends to higher dimension, an important observation of Santos that for a collapsing fluid with radial heat flow the isotropic pressure on the surface of discontinuity does not vanish. Some physically relevant parameters like luminosity, mass function for the bounded distribution and also the time required for horizon formation are also calculated and it is observed that the dimensionality of space-time does not qualitatively alter the analogous results of the ‘standard’ space time.

Non-adiabatic gravitational collapse of charged radiating fluid spheres

Dynamical equations governing the non-adiabatic collapse of a shear-free spherical distribution of unisotropic matter in the presence of charge are obtained. A brief outline of constructing a model describing collapse of a charged radiating fluid sphere in the set up developed is given.

Gravitational Collapse of Rotating Gaseous Ellipsoids

view Abstract Citations (56) References (5) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Gravitational Collapse of Rotating Gaseous Ellipsoids Fujimoto, M. Abstract The work of Rossner on the finite-amplitude oscillation of a Maclaurin ellipsoid is extended to the adiabatic and non-adiabatic gravitational collapse of a rotating uniform gaseous ellipsoid. The problem is made tractable by introducing an appropriate temperature distribution in the initial ellipsoid and by assuming a special formula for the cooling rate of the gas. Solutions can be represented by trajectories in the (al,a2,a3)-space, where ai, a2, and a~ are the lengths of the three principal axes of the ellipsoid. The adiabatic collapse is characterized by the same trajectories that represent non-linear adiabatic pulsations. They never reach any plane a, = 0 (j = 1, 2, 3) but are confined within a closed zero-velocity surface. The trajectories in the (ai,a2,a3)-space which represent the non-adiabatic collapse make one or more loops, depending on the cooling rate of the gas and the total angular momentum. They finally reach the plane a3 = 0; thus the ellipsoid ultimately becomes a flat disk. A small, finite, non-axisymmetric perturbation applied to an axisymmetric ellipsoid grows in the course of the collapse. For large angular momentum the resultant figure is a very thin, needle-like ellipsoid. An ellipsoid which initially has three unequal principal axes displays a peculiar gravitational collapse under the constraint of the circulation integral. The configuration may be elongated even if the angular mo- mentum is very small Publication: The Astrophysical Journal Pub Date: May 1968 DOI: 10.1086/149569 Bibcode: 1968ApJ...152..523F full text sources ADS |