Article
Physics, Particles & Fields
M. Z. Bhatti, S. Ijaz, Bander Almutairi, A. S. Khan
Summary: This paper analyzes the characteristics of a non-static sphere with an anisotropic fluid distribution in the background of modified f (G) theory. The presence of a conformal Killing vector allows for the computation of reliable results for the modified field equations. Various precise analytical solutions are obtained for both non-dissipative and dissipative systems by making different choices of the conformal Killing vector. The matching conditions in the context of f (G) gravity are computed and specific constraints are applied to determine significant results. The results of this study help in understanding the properties of astrophysical objects.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Astronomy & Astrophysics
Rui Xu, Dicong Liang, Lijing Shao
Summary: The article introduces the bumblebee gravity model, a vector-tensor theory of gravitation where the vector field couples to the Ricci tensor. Two families of black-hole solutions are found, one with a vanishing radial component of the vector field and the other with a vanishing radial component of the Ricci tensor. Numerical solutions are obtained for nonzero coupling between the vector field and the Ricci tensor. Other solutions with certain properties of academic interests are also discussed. The black-hole solutions are tested against Solar-System observations and images of supermassive black holes.
Article
Astronomy & Astrophysics
Masato Minamitsuji, Antonio De Felice, Shinji Mukohyama, Michele Oliosi
Summary: In this study, static and spherically symmetric solutions are investigated in the minimal theory of bigravity (MTBG). It is found that a pair of Schwarzschild-de Sitter spacetimes with different cosmological constants and black hole masses is a solution in the self-accelerating branch of MTBG, but not in the normal branch. It is also shown that the Schwarzschild-de Sitter solutions can become compatible with the normal branch by using different coordinates. Furthermore, it is confirmed that the self-accelerating branch of MTBG admits static and spherically symmetric general relativity solutions with matter written in the spatially flat coordinates, including neutron stars with arbitrary matter equations of state. Finally, it is demonstrated that nontrivial solutions in the self-accelerating branch are given by the Schwarzschild-de Sitter metrics written in nonstandard coordinates.
Article
Materials Science, Multidisciplinary
Abu Bakr Mehmood, Fiaz Hussain, Ashfaque H. Bokhari, Muhammad Ramzan, Muhammad Faryad, Tahir Hussain
Summary: This article addresses the problem of finding non-static plane symmetric perfect fluid solutions in the f(R, T) theory of gravity. The authors propose a classification for such spacetimes and calculate solutions within each class, finding both static and non-static geometries. The authors also analyze the Killing symmetries to determine the Lie symmetry groups admitted by the obtained spacetimes, finding a range of Killing vector fields.
RESULTS IN PHYSICS
(2022)
Article
Physics, Particles & Fields
Hamid R. Bakhtiarizadeh
Summary: We investigate new solutions to the Einstein-Maxwell equations with the presence of mimetic field in D dimensions, with a focus on the asymptotically anti-de Sitter case. We derive the solutions in detail in a five-dimensional spacetime and generalize them to higher dimensions. The solutions describe charged static and rotating solutions with different types of horizons and can be interpreted as black holes or black strings/branes based on their global features. We also examine various physical properties of the solutions, including horizons, singularities, entropy, mass, and angular momenta of rotating solutions.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Physics, Multidisciplinary
Iqra Nawazish, M. Sharif
Summary: This paper studies cosmic evolutionary stages in the background of a modified theory allowing for non-minimal coupling between various cosmological quantities. Different cosmic models are considered and analyzed, and exact solutions with different symmetries and conserved properties are derived. These solutions are found to be consistent with observational data and viability conditions, providing a successful explanation for cosmic accelerated expansion.
Article
Physics, Multidisciplinary
N. S. Kavya, V. Venkatesha, G. Mustafa, P. K. Sahoo, S. V. Divya Rashmi
Summary: In this study, new wormhole solutions are explored under the framework of new modified symbolscript symbolscript gravity. By using anisotropic matter distribution and a specific form of energy density, a characteristic wormhole solution is obtained. The isotropic case with a linear EoS relation is also discussed, and various physical attributes of the system under the wormhole geometry are investigated. Detailed analytical and graphical discussions on the matter contents via energy conditions are presented. The shape function of wormhole geometry satisfies the required conditions in both cases. Several interesting points and the features of the exotic matter within the wormhole geometry have been revealed. Finally, concluding remarks are provided.
CHINESE JOURNAL OF PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Sachin Kumar, Divya Jyoti, Kottakkaran Sooppy Nisar, M. Zakarya
Summary: The Bonnor field offers insights into the imposition of two magnetic poles in a symmetric axis, with mass m and strengths -m and m. New exact solutions of Einstein-Maxwell field equations in pure magnetic fields under the Bonnor metric have been obtained using the Lie symmetry method, showcasing accelerating static solutions on a semi-Riemannian manifold that is not conformally flat. Additionally, graphical representations in 3D are provided.
RESULTS IN PHYSICS
(2021)
Article
Physics, Particles & Fields
J. S. Goncalves, A. F. Santos
Summary: This paper examines the f(R, T, R μνP μν) gravity theory and its implications on causality. The analysis using Godel-type solutions shows that this model allows both causal and non-causal solutions, depending on the content of matter in the universe.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Physics, Multidisciplinary
M. Sharif, M. Zeeshan Gul
Summary: This paper investigates static wormhole solutions through Noether symmetry approach in the context of energy-momentum squared gravity, and finds that realistic traversable and stable wormhole solutions are obtained for a particular model of this gravity.
EUROPEAN PHYSICAL JOURNAL PLUS
(2021)
Article
Physics, Particles & Fields
Isil Basaran Oz, Kazuharu Bamba
Summary: The solutions for the field equations of f(R) gravity in static cylindrically symmetric space-time were investigated. Unknown values of the equations of state parameter were determined through the analysis of constraints obtained by using the Noether symmetry method. Several new exact solutions for cases of General Relativity in static cylindrically symmetrical space-time for the non-dust matter were discovered.
EUROPEAN PHYSICAL JOURNAL C
(2021)
Article
Physics, Multidisciplinary
Abdul Jawad, M. Bilal Amin Sulehri, Shamaila Rani
Summary: This article analyzes wormhole geometries in the perspective of non-minimal torsion-matter coupled gravity. Two energy density profiles for non-minimal coupled f(T) gravity models are proposed and analyzed for different viable solutions. The wormhole solutions obtained from these models violate the null energy condition for Casimir profile, while satisfying the null energy condition for Yukawa-Casimir profile. The stability of the obtained solutions is examined through the Tolman-Oppenheimer-Volkoff equation, showing stable results.
EUROPEAN PHYSICAL JOURNAL PLUS
(2022)
Article
Physics, Particles & Fields
K. Dialektopoulos, G. Leon, A. Paliathanasis
Summary: The Noether symmetry analysis is used to investigate a multiscalar field cosmological model in teleparallel gravity. Specifically, the study focuses on two scalar fields interacting in scalar-torsion theory. The field equations are described in a minisuperspace framework, and the evolution of physical variables depends on the potential function governing the dynamics of the scalar fields. By requiring the field equations to possess non-trivial Noether point symmetries and utilizing the first theorem of Noether, restrictions are imposed on the functional forms of the potential. Finally, symmetry vectors and corresponding conservation laws are employed to determine exact and analytic solutions in multiscalar-torsion cosmology.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Astronomy & Astrophysics
M. Sharif, Shehrbano Ahmed
Summary: This study presents new anisotropic solutions using gravitational decoupling technique, by adding a gravitational source in the matter distribution and decoupling the field equations through minimal geometric deformation approach. Three new solutions are derived by applying specific constraints and barotropic equation of state, with investigations on physical acceptability and stability through energy conditions and causality condition. It is concluded that all derived anisotropic solutions are physically viable and stable.
MODERN PHYSICS LETTERS A
(2021)
Article
Mathematics, Applied
Hongbin Chen, Rui Li, Ruofei Yao
Summary: The paper focuses on the qualitative properties of positive solutions to a semilinear elliptic equation in a planar sub-spherical sector. Monotonicity properties are proven within a certain range of amplitudes using the method of moving planes. Symmetry properties are derived from the uniqueness of the corresponding over-determined problem established by Farina and Valdinoci in 2013.