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Chakraborty, Subenoy

Publications and source records attributed to Chakraborty, Subenoy.

10 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Quantum cosmology for non-minimally coupled scalar field in FLRW space–time: A symmetry analysis

The present work deals with quantum cosmology for non-minimally coupled scalar field in the background of FLRW space–time model. The Wheeler–DeWitt equation is constructed and symmetry analysis is carried out. The Lie point symmetries are related to the conformal algebra of the minisuperspace while solution of the Wheeler–DeWitt equation is obtained using conserved currents of the Noether symmetries.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2019

Dynamical system analysis of Einstein–Skyrme model in a Kantowski–Sachs spacetime

The present work deals with anisotropic (but zero heat flux) Skyrme fluid with a constant radial profile in locally rotational Kantowski–Sachs spacetime in the background of Einstein gravity. By suitably change of variables the field equations are transformed to an autonomous system. To examine the stability of the system critical points are determined. For hyperbolic critical points the analysis of the system is done using Hartman–Grobman theorem, while center manifold theory is used to analyze non-hyperbolic critical points. Also stability at infinity is analyzed to visualize the global evolution of the Universe. As a result the 3D-phase space is identified with the Poincaré 3-sphere embedded in R{sup 4}. It is found that the parameters in the autonomous system play a crucial role for phase transition of the Universe. Finally possible bifurcation scenarios are discussed to identify the point of phase transition.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2019

Is Cold/Warm inflationary scenario a consequence of particle creation process ?

The present work describes a model of inflationary scenario with particle creation mechanism, in the frame work of non-equilibrium thermodynamics. In the background of homogeneous and isotropic spatially flat FLRW model of the Universe, the cosmic substratum is chosen as dissipative fluid. Here dissipation in the form of bulk viscous pressure is assumed to be due to particle creation formalism. For constant and slow-roll phases of (cold) inflationary scenario, the particle creation rate has been derived and an analogous inflaton field has been calculated. Finally an equivalence of the warm inflation with the present particle creation mechanism has been shown.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

Unified first law in inhomogeneous and anisotropic spacetime models: Some general prescription

In this paper we investigate the interrelationship between the unified first law of thermodynamics and the Friedmann equations for three anisotropic and inhomogeneous spacetime metrics namely Lemaître–Tolman–Bondi and Friedmann–Lemaître–Robertson–Walker type inhomogeneous spacetime model and Kantowski–Sachs type model. In all these models we find that Einstein field equations are obtained by projecting the unified first law along and perpendicular to the Kodama vector and also along two linearly independent directions.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

Cosmic scenarios in f(R) gravity: A complete evolution

The paper deals with f(R) gravity theory in the background of inhomogeneous FLRW-type space–time model. With proper choice of the inhomogeneous metric function it is possible to have an emergent scenario for the f(R)-cosmology. Explicit form of f(R) is obtained for power law expansion. It has been shown that the present f(R) gravity model is equivalent to some particle creation mechanism in Einstein gravity. Further a complete cosmic evolution from inflation to present late time acceleration is possible with proper continuous choices of the f(R)-functions. Finally, in the perspective of thermodynamical analysis a form of f(R) has been evaluated using the unified first law.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2018

Non-minimally coupled scalar field in Kantowski–Sachs model and symmetry analysis

The paper deals with a non-minimally coupled scalar field in the background of homogeneous but anisotropic Kantowski–Sachs space–time model. The form of the coupling function of the scalar field with gravity and the potential function of the scalar field are not assumed phenomenologically, rather they are evaluated by imposing Noether symmetry to the Lagrangian of the present physical system. The physical system gets considerable mathematical simplification by a suitable transformation of the augmented variables (a,b,ϕ)→(u,v,w) and by the use of the conserved quantities due to the geometrical symmetry. Finally, cosmological solutions are evaluated and analyzed from the point of view of the present evolution of the Universe.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2018

Evolving cosmic scenario in modified Chaplygin gas with adiabatic matter creation

Modified Chaplygin Gas has been successful in describing the cosmic history of the universe from radiation to ΛCDM in standard cosmology, while particle creation mechanism in nonlinear thermodynamics can be used to explain inflation as well as late time acceleration. The present work is an attempt to explore the possibilities of obtaining an alternative explanation to cosmic evolution when modified Chaplygin gas is used in the context of particle creation mechanism.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

Gravitational collapse of dissipative fluid as a source of gravitational waves

Gravitational collapse of cylindrical anisotropic fluid has been considered in analogy with the work of Misner and Sharp. Using Darmois matching conditions, the interior cylindrical dissipative fluid (in the form of shear viscosity and heat flux) is matched to an exterior vacuum Einstein–Rosen space–time. It is found that on the bounding 3-surface the radial pressure of the anisotropic perfect fluid is linearly related to the shear viscosity and the heat flux of the dissipative fluid on the boundary. This non-zero radial pressure on the bounding surface may be considered as the source of gravitational waves outside the collapsing matter distribution.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

A cosmological study in massive gravity theory

A detailed study of the various cosmological aspects in massive gravity theory has been presented in the present work. For the homogeneous and isotropic FLRW model, the deceleration parameter has been evaluated, and, it has been examined whether there is any transition from deceleration to acceleration in recent past, or not. With the proper choice of the free parameters, it has been shown that the massive gravity theory is equivalent to Einstein gravity with a modified Newtonian gravitational constant together with a negative cosmological constant. Also, in this context, it has been examined whether the emergent scenario is possible, or not, in massive gravity theory. Finally, we have done a cosmographic analysis in massive gravity theory.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗