Browsing by Author "E. Kahil, Magd"

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Equations of Motion for Charged Spinning Fluid in Bi-metric Type Theories of Gravity
(October university for modern sciences and Arts MSA, 2023) E. Kahil, Magd; A. Ammar, Samah; A. Refaey, Shymaa
The General theory of relativity is one of the most successful theories of gravity. Despite its successful applications, it has some difficulties in examining the behaviour of particles precisely in strong gravitational fields. Bi-metric type theories of gravity are classified as alternative theories of gravity that describing such strong gravitational fields, such as the gravitational field formed at the core of our galaxy. In order to obtain the equations of motion for spinning fluids, we use the Weyssenhoff tensor to express the spin fluid. The equations of motion for spinning fluids are derived using Euler-Lagrange equation. We present the equations of motion for spinning fluids and their corresponding spin deviation equations in some classes of Bi-metric type theories. Also, we obtain equations of motion for spinning fluids and their corresponding spin deviation for a variable mass. Moreover, we extend our study to examine the status of motion for spinning charged fluids and their corresponding spin deviation equations.
Equations of Motion for Spinning Fluids and their Deviation Equations in Finslerian Geometry
(October university for modern sciences and Arts MSA, 2023) E. Kahil, Magd; A. Ammar, Samah; A. Refaey, Shymaa
Finsler geometry is a natural extension of the Riemannian geometry and a good a platform used to interpret the infrastructure of physical phenomena, especially for relativistic applications. Accordingly it is worthy to study spinning fluids in the context of this geometry that would share their benefits in cosmological applications. Equations of motion of spinning fluids and their corresponding deviation equations are obtained. The problem of motion for studying a fluid with a variable mass is also obtained. The set of Equations of spinning fluids and spinning deviation fluids equations for some classes of the Finslerian geometry have been derived, using a modified type of the Bazanski Lagrangian. Due to the richness of the Finslerian geometry, a new perspective for revisiting the problem of stability is based on solving the deviation equations of spinning fluids in strong fields of gravity is performed. Such a problem has a direct application on examining the stability of accretion disk orbiting Sgr A*.
Spinning Equations for Objects of Some Classes in Finslerian Geometry
(arXiv preprint arXiv:2001.03331, 2020) E. Kahil, Magd
Spinning equations of Finslerian gravity, the counterpart of Mathisson-Papapetrou Spinning equations of motion are obtained. Two approaches of Finslerian geometries are illustrated, and their corresponding spinning equations. The significance of nonlinear connection and its relevance on spinning equations and their deviations ones are examined.
The spinning equations of motion for objects in AP-geometry
(arXiv preprint arXiv:1802.04058, 2018) E. Kahil, Magd
Equations of spinning objects are obtained in Absolute Parallelism Geometry [AP], a special class of non-Riemannian geometry admitting an alternative nonvanishing curvature and torsion simultaneously. This new set of equations is the counterpart of the Papapetrou equations in the Riemannian geometry. Applying, the concept of geometerization of physics, it may give rise to describe the spin tensor as parameterized commutation relation between path and path deviation equations in both Riemannian and non-Riemannian geometries.
Stability of Stellar Systems Orbiting SgrA
(arXiv preprint arXiv:1511.02424, 2015) E. Kahil, Magd
Path equations of different orbiting objects in the presence of very strong gravitational fields are essential to examine the impact of its gravitational effect on the stability of each system. Implementing an analogous method, used to examine the stability of planetary systems by solving the geodesic deviation equations to obtain a finite value of the magnitude of its corresponding deviation vectors. Thus, in order to know whether a system is stable or not, the solution of corresponding deviation equations may give an indication about the status of the stability for orbiting systems.Accordingly, two questions must be addressed based on the status of stability of stellar objects orbiting super-massive black holes in the galactic center. 1. Would the deviation equations play the same relevant role of orbiting planetary systems for massive spinning objects such as neutron stars or black holes? 2. What type of field theory which describes such a strong gravitational field ?