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Uttaran Ghosh

Publications and source records attributed to Uttaran Ghosh.

4 recordsLinked to original sources

Structure Scalars for Charged Dissipative Spherical Collapse in $f(R, T)$ Gravity

We examine the structure scalars constructed from the orthogonal splitting of the Riemann tensor for the spacetime metric describing the interior of a charged matter configuration undergoing dissipative collapse in the framework of $f(R,T)$ gravity (where $R$ and $T$ are the Ricci scalar and the trace of energy-momentum tensor, respectively), and also the way these quantities influence the various physical parameters of the collapsing matter. In absence of dissipation, the energy density inhomogeneity is found to be influenced by the structure scalar $X_{TF}$ and the mass-function of the collapsing matter. Further, the presence of charge affects the structure scalars and the total mass-energy content. The dependence of the various physical parameters like heat dissipation, energy density inhomogeneity, evolution of the expansion scalar, the shear scalar, effective homogeneous energy density, and pressure anisotropy on the structure scalars, have been clearly indicated along with a discussion on the complexity factor of the collapsing configuration. The $f(R,T)$ junction conditions have been presented, showing the matching conditions for the matter Lagrangian and their derivatives at the boundary. The energy conditions are also presented and the possibility of violation of the Strong Energy Condition has been discussed.

gr-qc

Formation of Singularity and Apparent Horizon for Dissipative Collapse in $f(R,T)$ Theory of Gravity

In this paper, we consider the spherically symmetric gravitational collapse of isotropic matter undergoing dissipation in the form of heat flux, with a generalized Vaidya exterior, in the context of $f(R, T)$ gravity. Choosing $f(R, T)=R+2\lambda T$, and applying the $f(R, T)$ junction conditions on the field equations for the interior and exterior regions, we have obtained matching conditions of the matter-Lagrangian and its derivatives across the boundary. The time of formation of singularity and the time of formation of apparent horizon have been determined and constraints on the integration constants are examined for which the final singularity is hidden behind the horizon.

gr-qc

Vaidya-like exterior solution and formation of singularity in $f(R, T)$ theory of gravity

In this paper, we study the gravitational collapse of a fluid ball undergoing dissipation in the form of heat flux, in the framework of $f(R,T)$ gravity. To apply the junction conditions in order to match the interior and the exterior spacetimes and analyze the dynamics of collapse, it is necessary to know the exterior metric for the radiating fireball, which is not yet available in the context of $f(R,T)$ gravity. Therefore, at the outset, we have determined the exterior Vaidya-like radiating metric in $f(R,T)$ gravity. Subsequently, we solved the $f(R,T)$ field equations and used the $f(R,T)$ junction conditions to match the exterior with the interior spacetime. The time of formation of the singularity and the time of formation of the apparent horizon have been determined. It is concluded that the final singularity is hidden behind the horizon.

gr-qc

Dynamical conditions and causal transport of dissipative spherical collapse in $f(R,T)$ gravity

In this paper, we have investigated the non-adiabatic spherical gravitational collapse in the framework of the $f(R,T)$ theory of gravity with a locally anisotropic fluid that undergoes dissipation in the form of heat flux, free-streaming radiation, and shearing viscosity. The dynamical equations are analyzed in detail, both in the Newtonian and post-Newtonian regimes. Finally we couple the dynamical equations to the full causal transport equation in the context of Israel-Stewart theory of dissipative systems. This yields us a better understanding of the collapse dynamics and may be connected to various astrophysical consequences.

gr-qc