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Muhammad Bilal Riaz

Publications and source records attributed to Muhammad Bilal Riaz.

3 recordsLinked to original sources

Dynamics of Charged Radiating Collapse with Shear and Anisotropy

We investigate a charged anisotropic radiating stellar configuration undergoing gravitational collapse in the presence of shear and heat flux within the Einstein Maxwell framework. The interior spacetime is described by a time dependent spherically symmetric geometry and is matched to an exterior charged Vaidya spacetime. The electromagnetic field is incorporated explicitly through Maxwell equations, allowing the electric charge to contribute to the matter variables, mass function, and boundary evolution. The charged junction condition is reduced to a Riccati type differential equation with suitable transformations and exact solution is obtained. The physical properties of the resulting shearing solution are examined through the energy density, radial and tangential pressures, pressure anisotropy, heat flux, electric charge, energy conditions, sound speeds, Herrera cracking criterion, and complexity factor. The energy density and radial pressure remain positive and decrease towards the stellar surface, whereas the tangential pressure remains negative, confirming the anisotropic character of the configuration. Heat transport and electromagnetic effects are strongest in the inner stellar region. The energy and causality conditions are satisfied. The cracking function indicates potential stability against cracking. The complexity factor remains positive, with electric charge providing an additional contribution alongside pressure anisotropy, density inhomogeneity, and dissipative heat flux. These results provide a comprehensive picture of the physical behavior and internal structure of the charged shearing radiative collapse model.

gr-qc

Nonlinear evolution of anisotropic matter configurations under higher-order curvature corrections

This study examines the dynamical evolution of self-gravitating systems in the presence of exotic matter within the framework of $f(R)$ gravity. Specifically, we have adopted the Starobinsky model $f(R) = R + αR^2$, which incorporates higher-order curvature corrections to describe nonlinear gravitational behavior. The analysis focuses on the nonlinear spherical evolution of anisotropic matter configurations and explains how dark matter influences their physical characteristics. The presence of dark matter is found to significantly affect the radial and tangential pressure distributions, thereby altering the overall dynamics of the system. The model is employed for the compact object $ Her~X-1$ described by the generalized Tolman-Kuchowicz metric, demonstrating a singularity-free behavior of the physical parameters. The results reveal that increasing the parameter $n$ of the generalized Tolman-Kuchowicz metric leads to striking variations in the model characteristics, highlighting its essential role in governing internal structure and evolution of the compact object. The model remains physically viable under different testing criteria like energy conditions, hydrostatic equilibrium condition, adiabatic index, causality conditions, Herrera's Cracking condition and mass-radius relation presented in this work.

gr-qc

Modeling Compact Objects in $f(R)$ Gravity: Application of Buchdahl-I Metric with Chaplygin Equation of State

This paper investigates realistic anisotropic matter configurations for spherical symmetry in the framework of $f(R)$ gravity. The solutions obtained from Buchdahl-I metric are used to determine the behavior of PSR J0740+6620, PSR J0348+0432 and 4U 1608-52 with Starobinsky model. Analysis of physical parameters such as density, pressure, and anisotropy is illustrated through graphs, and the stability of compact objects is investigated by energy and causality conditions. We will also discuss the behavior of gravitational, hydrostatic and anisotropic forces, gravitational redshift and adiabatic index. At the theoretical and astrophysical scales, the graphical representations validate the practical and realistic $f(R)$ gravity models.

gr-qc