Prabir Rudra

Vaidya Spacetime for Galileon Gravity's Rainbow

Abstract In this paper, we analyze Vaidya spacetime with an energy dependent metric in Galileon gravitys rainbow. This will be done using the rainbow functions which are motivated from the results obtained in loop quantum gravity approach and noncommutative geometry. We will investigate the Gravitational collapse in this Galileon gravitys rainbow. We will discuss the behavior of singularities formed from the gravitational collapse in this rainbow deformed Galileon gravity.

ROLE OF GENERALIZED COSMIC CHAPLYGIN GAS IN ACCELERATING UNIVERSE: A FIELD THEORETICAL PRESCRIPTION

In this paper, we investigate the role played by dark energy (DE) in the form of Generalized cosmic Chaplygin gas in an accelerating universe described by FRW cosmology. We have tried to describe the model from the theoretical point of view of a field, by introducing a scalar field ϕ and a self-interacting potential V(ϕ). The corresponding expressions for the field are obtained for the given model. Statefinder parameters have been used to characterize the dark energy model. Plots have been generated for characterizing different phases of universe diagrammatically and a comparative study is performed with the Modified Chaplygin gas model. As an outcome of the study, Generalized cosmic Chaplygin gas is identified as a much less constrained form of dark energy as compared to modified Chaplygin gas.

Vaidya spacetime in massive gravity's rainbow

Abstract In this paper, we will analyze the energy dependent deformation of massive gravity using the formalism of massive gravitys rainbow. So, we will use the Vainshtein mechanism and the dRGT mechanism for the energy dependent massive gravity, and thus analyze a ghost free theory of massive gravitys rainbow. We study the energy dependence of a time-dependent geometry, by analyzing the radiating Vaidya solution in this theory of massive gravitys rainbow. The energy dependent deformation of this Vaidya metric will be performed using suitable rainbow functions.

Coincidence problem in f(T) gravity models

It is well known fact that almost all the recent models of universe are plagued by the cosmic coincidence problem. In this assignment we try to probe the role played by torsion in the current scenario of coincidence and devise a set-up for its realization. In order to model the scenario, the energy arising from the torsion component is considered analogous to dark energy. An interaction between dark energy and dark matter is considered, which is by far the best possible tool to realize the coincidence. A set-up is designed and a constraint equation is obtained which screens the models of f(T) gravity that can successfully accommodate the stationary scenario in its framework, from those which cannot. Due to the absence of a universally accepted interaction term introduced by a fundamental theory, the study is conducted over three different forms of chosen interaction terms. As an illustration two widely known models of f(T) gravity are taken into consideration and used in the designed setup. The study reveals that the realization of the coincidence scenario as well as the role played by torsion in the current universe is a model dependent phenomenon. It is found that the first model showed a considerable departure from the stationary scenario. On the contrary the other four models are perfectly consistent with our setup and generated a satisfactory stationary scenario, thus showing their cosmological viability and their superiority over their counterparts. For the third model (exponential model) it was seen that the cosmological coincidence is realized only in the phantom regime. For the fourth (logarithmic model) and the fifth models, we see that the stationary scenario is attained for negative interaction values. This shows that the direction of flow must be from dark energy to dark matter unlike the previous models. Under such circumstances the universe will return from the present energy dominated phase to a matter dominated phase.

Generalised teleparallel quintom dark energy non-minimally coupled with the scalar torsion and a boundary term

Within this work, we propose a new generalised quintom dark energy model in the teleparallel alternative of general relativity theory, by considering a non-minimal coupling between the scalar fields of a quintom model with the scalar torsion component

Time dependent geometry in massive gravity

T

Reconstruction of f（R） Gravity with Ordinary and Entropy-Corrected（m,n）-Type Holographic Dark Energy Model

and the boundary term

Emergent Universe With Exotic Matter In Loop Quantum Cosmology, DGP Brane World and Kaluza-Klein Cosmology

B

Vaidya spacetime in Brans–Dicke gravity’s rainbow

. In the teleparallel alternative of general relativity theory, the boundary term represents the divergence of the torsion vector,

Observational Data Fitting to Constrain Variable Modified Chaplygin Gas in the Background of Horava-Lifshitz Gravity

B=2\nabla_{\mu}T^{\mu}