Article
Astronomy & Astrophysics
Aurelio Tamez Murguia, Manuel Vazquez-Nambo, Victor Manuel Yepez-Garcia, Nancy Cambron Munoz, Jose Oswald Tellez Vazquez
Summary: This work presents an exact interior solution to an Einstein-Maxwell equation system, which assumes a static and spherically symmetric spacetime with a distribution of matter representing a generalization of a model for a perfect chargeless fluid. The charge parameter modifies the mass function, compactness rate, and behavior of the speed of sound. The analysis of density, pressure, and charge shows that the solution is suitable for describing relativistic compact stars. Specifically, the behavior of these functions is analyzed for observed mass values in the range [0.95, 1.13] solar masses and theoretical radius values in the range [8.101, 8.501] km for the star LMC X-4. The maximum charge value Q - 1.73 x 10(20)C occurs at the maximum compactness u = 0:2059.
MODERN PHYSICS LETTERS A
(2023)
Article
Astronomy & Astrophysics
Artur Alho, Jose Natario, Paolo Pani, Guilherme Raposo
Summary: The study generalized Buchdahl's result by introducing the most general equation of state for elastic matter and computed the maximum compactness of self-gravitating objects in GR. It showed that elastic matter can exceed current theoretical limits but generally cannot reach the compactness of a black hole.
Article
Physics, Particles & Fields
Shavani Naicker, Sunil D. Maharaj, Byron P. Brassel
Summary: In this paper, the field equations for a charged gravitating perfect fluid in Einstein-Gauss-Bonnet gravity are derived in all spacetime dimensions. The static and spherically symmetric spacetime leads to a charged condition of pressure isotropy, which is a second-order Abel differential equation. It is shown that this equation can be simplified to a first-order, nonlinear canonical differential equation in higher dimensions. The canonical form allows for an exact solution generating algorithm, resulting in implicit solutions by choosing potentials and the electromagnetic field. An exact solution to the canonical equation is found, which corresponds to the neutral model previously discovered. Additionally, three new classes of solutions are obtained by placing constraints on the canonical differential equation, without specifying gravitational potentials and electromagnetic field. When the canonical form is not applicable, other classes of exact solutions are presented using elementary and special functions (the Heun confluent functions).
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Physics, Particles & Fields
B. V. Ivanov
Summary: The expressions in the Einstein-Maxwell equations serve as generating functions for charged stellar models, incorporating equation of state and conformal motion conditions. The resulting equations are linear first order differential equations and Riccati equations, which can always be transformed into second order homogeneous linear differential equations.
EUROPEAN PHYSICAL JOURNAL C
(2021)
Article
Physics, Particles & Fields
J. Andrade, D. Santana
Summary: In this work, a new interior isotropic extension of Einstein's universe solution is constructed using the gravitational decoupling framework and the extended minimal geometric deformation. The resulting model satisfies the fundamental physical acceptance conditions. Additionally, the energy exchange between the Einstein's fluid distribution and an extra perfect fluid supporting the resulting isotropic stellar configuration is studied.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Astronomy & Astrophysics
G. G. L. Nashed, Shinichi Nojiri
Summary: In this study, we derived a charged slowly rotating black hole solution with a dipole scalar field that is a distortion of the Kerr-Newman black hole solution. By investigating the propagation of photons near the black hole, we found that the difference between left- and right-handed polarizations is more pronounced compared to the Kerr-Newman black hole. Finally, we determined the stability condition using geodesic deviations.
Article
History & Philosophy Of Science
Patrick M. Duerr, Claudio Calosi
Summary: Super-substantivalism argues that spacetime is more fundamental than matter, and can directly account for the physical properties attributed to matter. The paper revisits an argument in favor of this view, presenting a critique that highlights the distinction between fundamentality and ontological dependence.
Article
Astronomy & Astrophysics
J. Kumar, H. D. Singh, A. K. Prasad
Summary: This paper investigates the stellar structure using the f(R, T) gravity theory, specifically considering the function f(R, T) = R + 2 sigma T. A stellar model is developed to explain the isotropic matter distribution within compact objects filled with perfect fluid, and its stability is demonstrated through various physical and stability conditions. The theory is shown to be acceptable by accurately collecting data for compact stars like PSR-B0943+10, CEN X-3, SMC X-4, Her X-1, and 4U1538-52.
PHYSICS OF THE DARK UNIVERSE
(2021)
Article
Astronomy & Astrophysics
Amit Kumar Prasad, Jitendra Kumar
Summary: This research presents a new class of exact solutions of the Einstein-Maxwell field equation for compact stars with uniform charged distributions based on Pseudo-spheroidal space-time. It explores the stability of the model, as well as physical characteristics such as pressure, redshift, and density, showing that the results are consistent with both physical requirements and observational data.
ASTROPHYSICS AND SPACE SCIENCE
(2021)
Article
Astronomy & Astrophysics
F. Cipolletta, J. Kalinani, E. Giangrandi, B. Giacomazzo, R. Ciolfi, L. Sala, B. Giudici
Summary: This article introduces a new version of the GRMHD code Spritz, with an added neutrino leakage scheme and a series of tests to verify its correct implementation. It also discusses the implementation of high-order methods in the Spritz code.
CLASSICAL AND QUANTUM GRAVITY
(2021)
Article
Physics, Multidisciplinary
Joaquin Estevez-Delgado, Joel Arturo Rodriguez Ceballos, Jorge Mauricio Paulin-Fuentes, Jose Vega Cabrera, Antonio Rendon Romero
Summary: This report generalizes the solution to Einstein's equations with perfect fluid to the case of Einstein-Maxwell with perfect fluid. The effect of the charge is determined by a parameter ν, which is constrained by the positivity condition from the pressure inside the star. It is shown that the solution is stable according to the Zeldovich criteria and the adiabatic index criteria. The presence of charge increases the compactness of the model, allowing it to represent stars with high compactness.
COMMUNICATIONS IN THEORETICAL PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
M. K. Jasim, S. K. Maurya, Saibal Ray, Dibyendu Shee, Debabrata Deb, Farook Rahaman
Summary: This paper discusses the existence of a compact strange (quark) star within the framework of Einstein's General Theory of Relativity with the Tolman V metric potential and uses the simplest form of MIT Bag equation of state to represent strange quark matter distribution. Various physical features and stability criteria are studied for different strange star candidates, and results show consistency with energy conditions, TOV equation, and adiabatic index. Different physical parameters are also calculated for three consecutive values of Bag constant, with a focus on the properties of strange star candidates with B = 90 MeV/fm³.
RESULTS IN PHYSICS
(2021)
Article
Astronomy & Astrophysics
Joaquin Estevez-Delgado, Gabino Estevez-Delgado, Noel Enrique Rodriguez Maya, Jose Martinez Pena, Aurelio Tamez Murguia
Summary: The model features a regular geometry and finite hydrostatic functions, with decreasing density and pressure inside and continuous connection with the exterior solution. The speeds of sound are lower than the speed of light, ensuring causal condition is not violated. The anisotropy effect can cause the radial sound speed to behave monotonically increasing or decreasing.
MODERN PHYSICS LETTERS A
(2021)
Article
Astronomy & Astrophysics
T. Celora, N. Andersson, G. L. Comer
Summary: A method for obtaining fully non-linear equations of motion for dissipative general relativistic multi-fluids is introduced, involving the explicit use of lower dimensional matter spaces. The goal is to compare these action-based results with more traditional methods, such as the Muller-Israel-Stewart model. By constructing self-consistent notions of equilibrium and developing first-order deviations on matter spaces, the dissipation terms of the action-based model are identified with first-order thermodynamical fluxes. This general framework can be applied to multi-fluid systems without available causal and stable models.
CLASSICAL AND QUANTUM GRAVITY
(2021)
Article
Astronomy & Astrophysics
Jose Damian Lopez, Miguel Alcubierre
Summary: We revisit the study of charged boson stars, which are solutions to the Einstein-Maxwell-Klein-Gordon system with spherical symmetry. We construct families of charged boson stars in the ground state, for various values of the charge parameter and the central scalar field. Our analysis confirms the existence of super-critical solutions for a limited range of charges above a critical value, but we find that these solutions are gravitationally unbound and therefore expected to be unstable. Interestingly, we find no super-critical solutions in which the total charge exceeds the total mass of the system.
GENERAL RELATIVITY AND GRAVITATION
(2023)
Article
Physics, Multidisciplinary
Mahmood Khalid Jasim, Sunil Kumar Maurya, Ksh Newton Singh, Riju Nag
Summary: In this study, a new anisotropic solution for the strange star model within 5D Einstein-Gauss-Bonnet gravity was investigated. The physical viability of the model was tested by matching a well-known Boulware-Deser solution at the boundary. Furthermore, the mass-radius relationship and hydrostatic equilibrium of the stellar system were analyzed to determine the compactness and surface redshift of the model.
Article
Physics, Particles & Fields
S. K. Maurya, Ksh. Newton Singh, M. Govender, Abdelghani Errehymy, Francisco Tello-Ortiz
Summary: In this article, the solution of the Einstein-Maxwell field equations in Brans-Dicke (BD) gravity with the presence of a massive scalar field describing a charged anisotropic strange star model is obtained using the embedding approach. The resulting model is rigorously tested for stability, causality, and regularity, and is able to accurately describe compact objects such as PSR J1903+327; Cen X-3; EXO 1785-248 and LMC X-4. The investigation reveals that the scalar field leads to higher surface charge densities, influencing the compactness of charged stars and altering physical characteristics of objects when the electric and scalar fields are coupled.
EUROPEAN PHYSICAL JOURNAL C
(2021)
Article
Physics, Particles & Fields
S. K. Maurya, Asma Mohammed Al Aamri, Athari Khalifa Al Aamri, Riju Nag
Summary: A new systematic approach to finding exact gravitationally decoupled anisotropic spherical solutions in the presence of electric charge is presented using the complete geometric deformation methodology. The study applies well-known mimic approaches and equation of state to determine deformation functions and discusses the physical properties and stability of the solution. Predictions for radii, mass-radius ratio, and thermodynamic observables for compact objects under different decoupling parameters are also provided.
EUROPEAN PHYSICAL JOURNAL C
(2021)
Article
Physics, Multidisciplinary
S. K. Maurya, Francisco Tello-Ortiz, M. Govender
Summary: This paper presents two new classes of solutions for compact objects in the framework of five-dimensional EGB gravity, utilizing the CGD formalism to generate anisotropic models from known isotropic solutions. The physical tests show that contributions from CGD suppress effective pressure while enhancing effective density and mass of the compact object, with the effects being modified by the EGB coupling constant. The differences in deformation functions between CGD and MGD predict varying stellar characteristics such as mass-to-radius ratios and surface redshifts.
FORTSCHRITTE DER PHYSIK-PROGRESS OF PHYSICS
(2021)
Article
Astronomy & Astrophysics
S. K. Maurya, Ksh Newton Singh, M. Govender, Sudan Hansraj
Summary: The recent advance in the minimal geometric deformation (MGD) method has sparked interest in investigating higher-curvature gravitational effects in relativistic astrophysics. This study models a strange star using the MGD technique within the framework of Einstein-Gauss-Bonnet gravity. The findings demonstrate the existence of stable compact objects with masses exceeding the mass of a black hole without the need for exotic matter.
ASTROPHYSICAL JOURNAL
(2022)
Article
Physics, Particles & Fields
S. K. Maurya, M. Govender, Simranjeet Kaur, Riju Nag
Summary: In this research, a hierarchical solution-generating technique is proposed for bounded compact objects in classical general relativity. The Minimum Gravitational Decoupling (MGD) Method and the generalized concept of Complexity are employed to obtain two classes of solutions as candidates for physically realizable compact objects.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Physics, Particles & Fields
S. K. Maurya, Riju Nag
Summary: In this paper, we discuss the role of gravitational decoupling in isotropizing the anisotropic solution of Einstein's field equations. We also analyze its influence on the complexity factor in static self-gravitating systems. Additionally, we propose a simple and effective technique to generate new solutions for self-gravitating objects using the complete geometric deformation approach.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Physics, Particles & Fields
S. K. Maurya, M. Govender, Ksh Newton Singh, Riju Nag
Summary: In this study, we investigate the characteristics of an anisotropic stellar object using the polytropic solution within the framework of Einstein-Gauss-Bonnet (EGB) gravity. Anisotropy is introduced through the minimally gravitational decoupling method. The analysis of the exact solution for the gravitational potentials reveals novel features of the compact object. The EGB coupling constant and the decoupling parameter are found to play important roles in modifying the effective density and radial profiles at each interior point of the object, as well as inducing a change in the trends of the effective tangential pressure.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Physics, Multidisciplinary
Simranjeet Kaur, S. K. Maurya, Sacheendra Shukla, Riju Nag
Summary: In this work, a non-singular spherically symmetric charged anisotropic stellar object is obtained in the context of f(R, T)-gravity theory. The field equations are derived and solved by using the MIT Bag model equation of state and Tolman-Kuchowicz ansatz. Various physical properties and stability of the proposed model are investigated.
CHINESE JOURNAL OF PHYSICS
(2022)
Article
Physics, Multidisciplinary
G. Mustafa, Abdelghani Errehymy, S. K. Maurya, M. K. Jasim, Allah Ditta
Summary: This manuscript explores the physical aspects of compact stars in f(tau, T) gravity using the Karori-Barua spacetime. It considers three specific compact star models and examines their physical acceptability through calculations and graphical analyses. The results show that the obtained solutions are physically viable and have good properties.
CHINESE JOURNAL OF PHYSICS
(2022)
Article
Physics, Multidisciplinary
S. K. Maurya, Abdelghani Errehymy, Riju Nag, Mohammed Daoud
Summary: In this paper, the authors investigate the impact of complexity on static and spherically symmetric self-gravitating systems. They use a minimal geometric deformation approach to generate new physically viable models for anisotropic matter distributions. The results demonstrate that solutions with non-zero complexity factor exhibit similar characteristics, while solutions with vanishing complexity factor show different behavior. Furthermore, the authors calculate the relationship between mass and complexity factor for the presented models.
FORTSCHRITTE DER PHYSIK-PROGRESS OF PHYSICS
(2022)
Article
Physics, Multidisciplinary
S. K. Maurya, Ksh Newton Singh, Abdelghani Errehymy
Summary: In this article, an anisotropic solution for compact static spherically symmetric objects in the context of five-dimensional Einstein-Gauss-Bonnet (EGB) theory is investigated. The study focuses on the class of compact stars also known as strange stars. The results show the influence of parameter tuning on the inner geometry and physical properties of the compact stars.
EUROPEAN PHYSICAL JOURNAL PLUS
(2022)
Article
Physics, Nuclear
S. K. Maurya, B. Mishra, Saibal Ray, Riju Nag
Summary: This study investigates the decoupling of gravitational sources in the framework of f(R,T) gravity, using geometric deformation techniques to find exact solutions for anisotropic astrophysical systems without specific assumptions. By utilizing 5-dimensional Euclidean spacetime to describe embedding Class I spacetime, solvable spherical physical systems were obtained, demonstrating new possibilities for research. The mixture of f(R,T)+ CGD offers insights beyond pure General Relativity, enhancing the interior astrophysical features of compact stellar objects, with physical tests confirming the stability and acceptability of the solutions obtained.
Article
Astronomy & Astrophysics
M. K. Jasim, Ksh. Newton Singh, Abdelghani Errehymy, S. K. Maurya, M. V. Mandke
Summary: In this paper, the authors explore the possibility of exact solutions for anisotropic stellar systems using the massive Brans-Dicke theory of gravity. They use the minimal geometric deformation method and the embedding class-one space-time to study anisotropic solutions for matter sources. They also analyze the physical characteristics of anisotropic celestial objects by conducting several physical tests.
Article
Physics, Particles & Fields
S. K. Maurya, Ayan Banerjee, Anirudh Pradhan, Dhananjay Yadav
Summary: In this study, the possibility of the existence of compact charged spheres made of a charged perfect fluid in five-dimensional spacetime within the framework of Einstein-Gauss-Bonnet theory was investigated. Using a systematic and direct approach called minimal geometric deformation, it was proven that the fluid must be anisotropic and an exact and physically acceptable solution was found.
EUROPEAN PHYSICAL JOURNAL C
(2022)
