Please use this identifier to cite or link to this item: http://prr.hec.gov.pk/jspui/handle/123456789/19736
Title: Some Aspects of Self-interacting Brans-Dicke Theory
Authors: Majid, Amal
Keywords: Physical Sciences
Mathematics
Issue Date: 2022
Publisher: University of the Punjab , Lahore
Abstract: This thesis focuses on the study of various cosmological and astrophysical aspects in the framework of self-interacting Brans-Dicke gravity. Firstly, we explore the physical attributes of a static as well as a dynamical source that induce complexity within the fluid. We orthogonally split the Riemann tensor to obtain structure scalars relating to comoving congruence and Tolman mass. We define the complexity factor with the help of these scalars to demonstrate the complex nature of the system. Moreover, the vanishing complexity condition is used to obtain solutions. The factors that induce complexity in an initially complexity-free dynamical system are also examined. Secondly, we extend isotropic non-static spherical spacetime to anisotropic domain by means of minimal geometric deformation. This deformation decouples the system of field equations into two sets, one describing the isotropic matter field and the other governed by anisotropic source. The former array is evaluated by assuming the metric potentials of Friedmann-Lemaˆıtre-Robertson-Walker spacetime. We construct the anisotropic extension corresponding to power-law forms of scalar field and scale factor. Moreover, a linear equation of state links density and pressure of the configuration. We investigate physical behavior of the anisotorpic version for different values of the equation of state parameter. Thirdly, we adopt extended gravitational decoupling method to extend known static spherical solutions. Deformations in radial as well as temporal metric com ponents disintegrate the system of field equations into two arrays. We employ the metric functions of Tolman IV, Krori-Barua and Schwarzschild metrics to specify the set related to the seed source. In order to construct a suitable solution of the second xiv system, constraints are applied on the additional source and metric potentials. The impact of the massive scalar field as well as the decoupling parameter on the salient characteristics of the extended solutions is analyzed graphically. Finally, we generate an anisotropic solution for a static sphere filled with quark matter. The system of field equations is derived for specific form of potential func tion by employing the MIT bag model. The unknown metric tensors are evaluated through a well-behaved function along with the condition for class-one embedding. The unknown constants are specified in terms of mass and radius of the configuration with the help of junction conditions. We estimate the radius of LMC X-4 for different values of the bag constant by employing the star’s observed mass. We also discuss the physical viability and stability of the model through various tests.This thesis focuses on the study of various cosmological and astrophysical aspects in the framework of self-interacting Brans-Dicke gravity. Firstly, we explore the physical attributes of a static as well as a dynamical source that induce complexity within the fluid. We orthogonally split the Riemann tensor to obtain structure scalars relating to comoving congruence and Tolman mass. We define the complexity factor with the help of these scalars to demonstrate the complex nature of the system. Moreover, the vanishing complexity condition is used to obtain solutions. The factors that induce complexity in an initially complexity-free dynamical system are also examined. Secondly, we extend isotropic non-static spherical spacetime to anisotropic domain by means of minimal geometric deformation. This deformation decouples the system of field equations into two sets, one describing the isotropic matter field and the other governed by anisotropic source. The former array is evaluated by assuming the metric potentials of Friedmann-Lemaˆıtre-Robertson-Walker spacetime. We construct the anisotropic extension corresponding to power-law forms of scalar field and scale factor. Moreover, a linear equation of state links density and pressure of the configuration. We investigate physical behavior of the anisotorpic version for different values of the equation of state parameter. Thirdly, we adopt extended gravitational decoupling method to extend known static spherical solutions. Deformations in radial as well as temporal metric com ponents disintegrate the system of field equations into two arrays. We employ the metric functions of Tolman IV, Krori-Barua and Schwarzschild metrics to specify the set related to the seed source. In order to construct a suitable solution of the second xiv system, constraints are applied on the additional source and metric potentials. The impact of the massive scalar field as well as the decoupling parameter on the salient characteristics of the extended solutions is analyzed graphically. Finally, we generate an anisotropic solution for a static sphere filled with quark matter. The system of field equations is derived for specific form of potential func tion by employing the MIT bag model. The unknown metric tensors are evaluated through a well-behaved function along with the condition for class-one embedding. The unknown constants are specified in terms of mass and radius of the configuration with the help of junction conditions. We estimate the radius of LMC X-4 for different values of the bag constant by employing the star’s observed mass. We also discuss the physical viability and stability of the model through various tests.
Gov't Doc #: 25174
URI: http://prr.hec.gov.pk/jspui/handle/123456789/19736
Appears in Collections:PhD Thesis of All Public / Private Sector Universities / DAIs.

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