Ragab Mohamed Gad
Current Organizations / Institutes
The organizations/institutes from the scholar's latest article
Previous Organizations / Institutes
The organizations / institutes from the scholar's other articles in the past ten years
Research Subjects
Ragab Mohamed Gad has a total of 15 co-authors. Here are the top co-authors by number of shared publications:
- Awatif Al-Jedani
Department of Mathematics and Statistics, College of Science, University of Jeddah, Jeddah 23890, Saudi Arabia
3 shared publications A. Fouad
Minia University
2 shared publications- A. S. Alofi
King Abdulaziz University
2 shared publications - R. Schimming
Institut für Mathematik und informatik Universität Graeifswald D-17487 Greifswald Germany
2 shared publications A. E. Al Mazrooei
Mathematics Department Faculty of Science University of Jeddah 21589 Jeddah KSA
1 shared publicationA.S. Alofi
Mathematics Department, Faculty of Science, King Abdulaziz University
1 shared publication
Latest Publications
- Open Access
On LRS Space-Times Admitting Conformal Motions
In this paper, we study the conformal symmetry for locally rotationally symmetric Bianchi type I space-time. New exact conformal solutions of Einstein’s field equations for this space-time were obtained. The space-time geometry of these solutions is found to be non-vacuum, conformally flat, and shear-free. We show that in order for LRS Bianchi type I space-time to admit a conformal vector field it must reduce to the FRW space-time. Some physical and kinematic properties of the obtained conformal solutions are also discussed.
Open AccessOn LRS Space-Times Admitting Conformal Motions
In this paper, we study the conformal symmetry for locally rotationally symmetric Bianchi type I space-time. New exact conformal solutions of Einstein’s field equations for this space-time were obtained. The space-time geometry of these solutions is found to be non-vacuum, conformally flat, and shear-free. We show that in order for LRS Bianchi type I space-time to admit a conformal vector field it must reduce to the FRW space-time. Some physical and kinematic properties of the obtained conformal solutions are also discussed.
- Open Access
Conformal Solutions of Static Plane Symmetric Cosmological Models in Cases of a Perfect Fluid and a Cosmic String Cloud
In this work, we obtained exact solutions of Einstein’s field equations for plane symmetric cosmological models by assuming that they admit conformal motion. The space-time geometry of these solutions is found to be nonsingular, non-vacuum and conformally flat. We have shown that in the case of a perfect fluid, these solutions have an energy-momentum tensor possessing dark energy with negative pressure and the energy equation of state is . We have shown that a fluid has acceleration, rotation, shear-free, vanishing expansion, and rotation. In the case of a cosmic string cloud, we found that the tension density and particle density decrease as the fluid moves along the direction of the strings, then vanish at infinity. We shown that the exact conformal solution for a static plane symmetric model reduces to the well-known anti-De Sitter space-time. We obtained that the space-time under consideration admits a conformal vector field orthogonal to the 4-velocity vector and does not admits a vector parallel to the 4-velocity vector. Some physical and kinematic properties of the resulting models are also discussed.Open AccessConformal Solutions of Static Plane Symmetric Cosmological Models in Cases of a Perfect Fluid and a Cosmic String Cloud
In this work, we obtained exact solutions of Einstein’s field equations for plane symmetric cosmological models by assuming that they admit conformal motion. The space-time geometry of these solutions is found to be nonsingular, non-vacuum and conformally flat. We have shown that in the case of a perfect fluid, these solutions have an energy-momentum tensor possessing dark energy with negative pressure and the energy equation of state is . We have shown that a fluid has acceleration, rotation, shear-free, vanishing expansion, and rotation. In the case of a cosmic string cloud, we found that the tension density and particle density decrease as the fluid moves along the direction of the strings, then vanish at infinity. We shown that the exact conformal solution for a static plane symmetric model reduces to the well-known anti-De Sitter space-time. We obtained that the space-time under consideration admits a conformal vector field orthogonal to the 4-velocity vector and does not admits a vector parallel to the 4-velocity vector. Some physical and kinematic properties of the resulting models are also discussed. - Open Access
Conformal Solutions of Static Plane Symmetric Cosmological Models in Cases of a Perfect Fluid and a Cosmic String Cloud
In this work, we obtained exact solutions of Einstein's field equations for plane symmetric cosmological models by assuming that thy admit conformal motion. The space-time geometry of these solutions is found to be nonsingular, non-vacuum and conformally flat. We have shown that in the case of a perfect fluid, these solutions have an energy-momentum tensor possessing dark energy with negative pressure and the energy equation of state is $ρ+p=0$. We have shown that a fluid has acceleration, rotation, shear-free, vanishing expansion, and rotation. In the case of a cosmic string cloud, we found that the tension density and particle density decrease as the fluid moves along the direction of the strings, then vanish at infinity. We shown that the exact conformal solution for a static plane symmetric model reduces to the the well-known anti-De Sitter space time. We obtained that the space-time under consideration admits a conformal vector field orthogonal to the four-velocity vector and does not admits a vector parallel to the four-velocity vector. Some physical and kinematic properties of the resulting models are also discussed.Open AccessConformal Solutions of Static Plane Symmetric Cosmological Models in Cases of a Perfect Fluid and a Cosmic String Cloud
In this work, we obtained exact solutions of Einstein's field equations for plane symmetric cosmological models by assuming that thy admit conformal motion. The space-time geometry of these solutions is found to be nonsingular, non-vacuum and conformally flat. We have shown that in the case of a perfect fluid, these solutions have an energy-momentum tensor possessing dark energy with negative pressure and the energy equation of state is $ρ+p=0$. We have shown that a fluid has acceleration, rotation, shear-free, vanishing expansion, and rotation. In the case of a cosmic string cloud, we found that the tension density and particle density decrease as the fluid moves along the direction of the strings, then vanish at infinity. We shown that the exact conformal solution for a static plane symmetric model reduces to the the well-known anti-De Sitter space time. We obtained that the space-time under consideration admits a conformal vector field orthogonal to the four-velocity vector and does not admits a vector parallel to the four-velocity vector. Some physical and kinematic properties of the resulting models are also discussed. - 1 January 2024
- Published by Canadian Science Publishing in Canadian Journal of Physics
- Vol. 102 (1) , 54-60
On torsion axial vector and gravitational energy in Lewis–Papapetrou space-time in the theory of teleparallel gravity
The teleparallel version of Lewis–Papapetrou space-time is investigated. For this space-time, the true discussion of the geometric and physical properties is given. We show that the value of the space-like torsion-axial vector does not depend on the choice of tetrad field. Consequently, the spin procession of the Dirac particle and the corresponding Hamiltonian have physical meaning. The energy and momentum densities for such space-time are calculated. We show that when choosing two sets of tetrad fields, the dependence and independence of the aforementioned quantities on the tetrad field depend on the Lorentz factor, which links the two sets of tetrad fields.
- 1 January 2024
- Published by Canadian Science Publishing in Canadian Journal of Physics
- Vol. 102 (1) , 54-60
On torsion axial vector and gravitational energy in Lewis–Papapetrou space-time in the theory of teleparallel gravity
The teleparallel version of Lewis–Papapetrou space-time is investigated. For this space-time, the true discussion of the geometric and physical properties is given. We show that the value of the space-like torsion-axial vector does not depend on the choice of tetrad field. Consequently, the spin procession of the Dirac particle and the corresponding Hamiltonian have physical meaning. The energy and momentum densities for such space-time are calculated. We show that when choosing two sets of tetrad fields, the dependence and independence of the aforementioned quantities on the tetrad field depend on the Lorentz factor, which links the two sets of tetrad fields.
- 7 May 2021
- Published by Springer Nature in Indian Journal of Physics
- Vol. 96 (5) , 1591-1597
Gravitational energy in Van Stockum space-time
- 7 May 2021
- Published by Springer Nature in Indian Journal of Physics
- Vol. 96 (5) , 1591-1597
Gravitational energy in Van Stockum space-time
- Open Access
On Torsion Axial Vector and gravitational Energy in Lewis-Papapetrou Space-Time in the Theory of Teleparallel Gravity
The teleparallel version of Lewis-Papapetrou space-time is investigated. For this space-time the true discussion of the geometric and physical properties is given. We show that the value of space-like torsion-axial vector does not depend on the choice of tetrad field. Consequently, the spin procession of the Dirac particle and the corresponding Hamiltonian do. The energy and momentum densities for such space-time are calculated. We show that when choosing two sets of tetrad fields the dependence and independence of the aforementioned quantities on the tetrad field depend on the Lorentz factor, which links the two sets of tetrad fields.
Open AccessOn Torsion Axial Vector and gravitational Energy in Lewis-Papapetrou Space-Time in the Theory of Teleparallel Gravity
The teleparallel version of Lewis-Papapetrou space-time is investigated. For this space-time the true discussion of the geometric and physical properties is given. We show that the value of space-like torsion-axial vector does not depend on the choice of tetrad field. Consequently, the spin procession of the Dirac particle and the corresponding Hamiltonian do. The energy and momentum densities for such space-time are calculated. We show that when choosing two sets of tetrad fields the dependence and independence of the aforementioned quantities on the tetrad field depend on the Lorentz factor, which links the two sets of tetrad fields.
- Open Access
On Axially Symmetric Space-Times Admitting Homothetic Vector Fields in Lyra's Geometry
This paper investigates axially symmetric space-times that admit a homothetic vector field based on Lyra's geometry. The cases when the displacement vector is a function of $t$ and when it is constant are studied. In the context of this geometry, we find and classify the solutions of the Einstein's field equations (EFE) for the space-time under consideration, which display a homothetic symmetry.Open AccessOn Axially Symmetric Space-Times Admitting Homothetic Vector Fields in Lyra's Geometry
This paper investigates axially symmetric space-times that admit a homothetic vector field based on Lyra's geometry. The cases when the displacement vector is a function of $t$ and when it is constant are studied. In the context of this geometry, we find and classify the solutions of the Einstein's field equations (EFE) for the space-time under consideration, which display a homothetic symmetry. - Open Access
Homothetic Motion in a Bianchi Type-I Model in Lyra Geometry
In this paper we study a homothetic vector field of a Bianchi type-I model based on Lyra geometry. The cases when a displacement vector is function of $t$ and when it is constant are considered. In both two cases we investigate the equation of state. A comparison between the obtained results, using Lyra geometry, and that have obtained previously in the context of General Relativity, based on Riemannian geometry, will be given.Open AccessHomothetic Motion in a Bianchi Type-I Model in Lyra Geometry
In this paper we study a homothetic vector field of a Bianchi type-I model based on Lyra geometry. The cases when a displacement vector is function of $t$ and when it is constant are considered. In both two cases we investigate the equation of state. A comparison between the obtained results, using Lyra geometry, and that have obtained previously in the context of General Relativity, based on Riemannian geometry, will be given. - 22 January 2015
- Published by Springer Nature in International Journal of Theoretical Physics
- Vol. 54 (8) , 2932-2941
Homothetic Motion in a Bianchi Type-I Model in Lyra Geometry
- 22 January 2015
- Published by Springer Nature in International Journal of Theoretical Physics
- Vol. 54 (8) , 2932-2941
Homothetic Motion in a Bianchi Type-I Model in Lyra Geometry
- Open Access
Inhomogeneous Bianchi Type I Cosmological Model with Electromagnetic Field in Lyra Geometry
We have investigated an inhomogeneous Bianchi type-I cosmological model with electromagnetic field based on Lyra geometry. A new class of exact solutions have been obtained by considering the potentials of metric and displacement field are functions of coordinates t and x. The physical behavior of the obtained model is discussed.
Open AccessInhomogeneous Bianchi Type I Cosmological Model with Electromagnetic Field in Lyra Geometry
We have investigated an inhomogeneous Bianchi type-I cosmological model with electromagnetic field based on Lyra geometry. A new class of exact solutions have been obtained by considering the potentials of metric and displacement field are functions of coordinates t and x. The physical behavior of the obtained model is discussed.