Article
Astronomy & Astrophysics
Andrew DeBenedictis, Saga Ilijic, Marko Sossich
Summary: This paper studies the properties that the vacuum must have in the minimal extension of the teleparallel equivalent of general relativity. It is found that the mathematical conditions on the vacuum mimic those of general relativity and that certain restrictions on the existence of smooth horizons and singularities are necessary. The analysis also suggests that static spherical matter distributions may have extra restrictions on their spatial extent and stress-energy bounds to ensure the validity of vacuum solutions.
Article
Astronomy & Astrophysics
Alexey Golovnev, Maria-Jose Guzman
Summary: We study the properties of static spherically symmetric solutions in f(T) gravity by generalizing Bianchi identities and reducing the search for solutions to two simple equations. One equation is independent of the function f and describes the properties of solutions in any f(T) theory, while the other is the radial equation that identifies which function f is suitable for a chosen solution. Using these equations, we find exact and perturbative solutions for arbitrary and specific choices of f.
Article
Astronomy & Astrophysics
Wenyi Wang, Hua Chen, Taishi Katsuragawa
Summary: This study analyzes the theoretical solutions of f(Q) gravity, revealing restrictions on its functional form and studying the properties of Schwarzschild-like solutions in nontrivial f(Q) gravity.
Article
Physics, Particles & Fields
Marco Calza, Lorenzo Sebastiani
Summary: In this paper, we analyze a class of topological static spherically symmetric vacuum solutions in Q-gravity. We consider an Ansatz that ensures these solutions trivially satisfy the field equations when the non-metricity scalar is constant. Specifically, we provide and discuss local solutions in the form of black holes and traversable wormholes.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Physics, Nuclear
Moreshwar Tayde, Zinnat Hassan, P. K. Sahoo, Sashideep Gutti
Summary: In this study, we obtain wormhole solutions in the context of f(Q,T) gravity and investigate their properties using different forms of the gravitational Lagrangian.
Article
Physics, Multidisciplinary
S. A. Mardan, Umm-e-Farva Moeed, I. Noureen, Adnan Malik
Summary: The main objective of this work is to develop a novel general framework for generating solutions of stellar models in f(R) theory of gravity with class one metric. Such framework is not available in the vicinity of f(R) gravity. The relations of anisotropy factor, which is based on radial and tangential pressure, serve as the main source of generating solutions. The linear equation of state and conformally flat condition for class one metric are used to develop a consistent system of differential equations. We conclude that it is possible to develop generating solutions for the systems in f(R) gravity.
EUROPEAN PHYSICAL JOURNAL PLUS
(2023)
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
Physics, Multidisciplinary
Sweeti Kiroriwal, Jitendra Kumar, S. K. Maurya, Sourav Chaudhary
Summary: In this study, we examined new spherically symmetric wormhole solutions in modified symmetric teleparallel gravity theory. Constructing traversable wormholes with physically reasonable energy conditions and investigating their stability, we found that violations of energy conditions in gravity theory provide a viable framework for the study of wormholes.
Article
Physics, Nuclear
Moreshwar Tayde, Sayantan Ghosh, P. K. Sahoo
Summary: In this study, we analyze traversable wormhole solutions within the linear f(Q, T) = alpha Q + beta T gravity framework, ensuring the satisfaction of all energy conditions throughout spacetime. The solutions are obtained through a comprehensive analytical examination of the wormhole model's parameter space, considering the exponents governing redshift and shape functions, the wormhole throat radius (r(0)), redshift function value at the throat (phi(0)), and model parameters (alpha and beta). Bounds on these free parameters are established to guarantee energy condition satisfaction and provide two solutions. Additionally, the stability of a thin-shell around the wormhole is observed using the Israel junction condition. Finally, the null energy condition criteria and the potential for the thin-shell are calculated, along with their variations based on the chosen shape function.
Article
Physics, Multidisciplinary
Fiaz Hussain, Murtaza Ali, Muhammad Ramzan, Sabiha Qazi
Summary: In this paper, the classification of static spherically symmetric perfect fluid space-times in the context of f(T) gravity using conformal vector fields (CVFs) is explored. The study reveals that in three cases, the considered space-times have proper CVFs in the framework of f(T) gravity. In one case, the space-time admits proper homothetic vector fields, while in the remaining 16 cases, the space-times either become conformally flat or admit Killing vector fields.
COMMUNICATIONS IN THEORETICAL PHYSICS
(2022)
Article
Astronomy & Astrophysics
Abdelghani Errehymy, Sudan Hansraj, S. K. Maurya, Chevarra Hansraj, Mohammed Daoud
Summary: In this paper, the authors study spherically symmetric traversable wormholes in the torsion and matter coupling gravity formalism. They thoroughly investigate the field equations for wormhole solutions and find the violation of null energy conditions in the throat vicinity. By considering specific choices for matter content, they present an intriguing new class of solutions for static and spherically symmetric wormholes that obey the necessary metric conditions.
PHYSICS OF THE DARK UNIVERSE
(2023)
Article
Astronomy & Astrophysics
Rui-Hui Lin, Xiang-Hua Zhai
Summary: General relativity can be formulated equivalently with a non-Riemannian geometry involving a nonmetricity Q but vanishing curvature R and torsion T. Modification based on this description leads to f(Q) gravity. The application of f(Q) gravity to spherically symmetric configurations is explored, demonstrating effects on external and internal solutions of compact stars through different modifications.
Article
Physics, Particles & Fields
Isil Basaran Oz, Kazuharu Bamba
Summary: This paper investigates the f(R) theory in static cylindrically symmetric and plane-symmetric spacetimes. Solutions to the field equations of these models are found using the Noether symmetry method, leading to the discovery of new solutions. Additionally, the GR limit for each case is examined.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Physics, Particles & Fields
Kourosh Nozari, Sara Saghafi, Fateme Aliyan
Summary: This paper studies the motion of electrically neutral and charged particles around a regular spherically symmetric MOG dark compact object to explore their related ISCO and energy flux. Furthermore, the accretion of perfect fluid onto the regular spherically symmetric MOG dark compact object is investigated. The results show that the MOG parameter increases the ISCO radius of test particles while decreasing the corresponding energy flux. In addition, the energy density and the radial component of the four-velocity of the infalling fluid decrease near the central source as the MOG parameter increases.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Astronomy & Astrophysics
Sebastian Murk, Daniel R. Terno
Summary: The existence of black holes, a key prediction of general relativity, is an important consistency test for modified gravity theories. This study derived constraints that any self-consistent modified theory of gravity must satisfy to be compatible with the existence of black holes. The properties and characteristic features of these black holes were analyzed using the Starobinsky model, with both solutions in general relativity considered as zeroth-order terms in perturbative solutions.
Article
Astronomy & Astrophysics
Matteo Luca Ruggiero, Lorenzo Iorio
JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS
(2020)
Editorial Material
Astronomy & Astrophysics
Matteo Luca Ruggiero
Article
Physics, Multidisciplinary
Angelo Tartaglia, Matteo Luca Ruggiero
Summary: This paper investigates the geometry of a charged mass with angular momentum, described by the Kerr-Newman solution of the Einstein equations. The peculiar symmetry of the system is usually explained in terms of the gravito-magnetic field generated by the angular momentum of the source, resulting in the generalized Sagnac effect. The study of the asymmetry in the times of flight of counter-rotating light beams along a circular trajectory reveals that this asymmetry is independent of the charge and Newton's constant, only associated with the symmetry produced by the gravitomagnetic field.
Article
Astronomy & Astrophysics
Angelo Tartaglia, Massimo Bassan, Lorenzo Casalino, Mariateresa Crosta, Mario Lattanzi, Enrico Lorenzini, David Lucchesi, Roberto Peron, Giuseppe Pucacco, Matteo Luca Ruggiero, Francesco Santoli, Pavol Valko, Alberto Vecchiato, Francesco Vespe, Massimo Visco
Summary: This passage proposes placing transponders and atomic clocks in at least three of the Lagrange points of the Sun-Earth pair to exploit the time of flight asymmetry of electromagnetic signals. The main objective of this detection is to use the gravito-magnetic field to detect the galactic dark halo and potentially discover related opportunities.
EXPERIMENTAL ASTRONOMY
(2021)
Article
Education, Scientific Disciplines
Matteo Luca Ruggiero
Summary: This paper discusses the basic features of gravitational waves science and the limitations of traditional approaches to gravitational wave physics, proposing the use of Fermi coordinates to introduce a gravitoelectromagnetic analogy as a more suitable teaching method.
AMERICAN JOURNAL OF PHYSICS
(2021)
Article
Astronomy & Astrophysics
Lorenzo Iorio, Matteo Luca Ruggiero
Summary: This paper focuses on the secular changes of orbital elements of a planet in the solar system determined by the magnetic-like part of a gravitational wave field. The total force acting on a test particle is made of gravito-electric and gravito-magnetic contributions, with the latter depending on the particle's velocity. The effects of gravito-magnetic force are found to be much smaller than gravito-electric ones in terms of orbital eccentricity orders.
INTERNATIONAL JOURNAL OF MODERN PHYSICS D
(2021)
Article
Astronomy & Astrophysics
Matteo Luca Ruggiero
Summary: The linear gravitoelectromagnetic approach converts Einstein's equations into Maxwell-like equations to explain gravitational effects in the solar system under weak-field and slow-motion approximation. The analogy allows for further examination of gravitoelectromagnetic fields in non-stationary conditions and their application in describing test particle motion similar to Lorentz-like force equations starting from known solutions of Einstein's equations.
Article
Engineering, Aerospace
Matteo Luca Ruggiero, Angelo Tartaglia, Lorenzo Casalino
Summary: This article investigates a relativistic positioning system where the coordinates of the users are determined by the proper times broadcasted by clocks in motion in spacetime, known as emission coordinates. The study shows that emission coordinates in flat spacetime can be defined using simple geometrical properties of geodesic triangles, and an analytic solution for the receiver coordinates is obtained.
ADVANCES IN SPACE RESEARCH
(2022)
Article
Astronomy & Astrophysics
Matteo Luca Ruggiero, Antonello Ortolan, Clive C. Speake
Summary: It is well known that the rotation curves of galaxies cannot be explained by Newtonian gravity in the absence of dark matter. Even in the weak-field approximation, there exist general relativistic effects without a Newtonian counterpart, such as gravitomagnetic effects, which may play a relevant role in understanding the impact of dark matter on galactic dynamics.
CLASSICAL AND QUANTUM GRAVITY
(2022)
Article
Astronomy & Astrophysics
Matteo Luca Ruggiero
Summary: The interaction between plane gravitational waves and test masses can be described using Fermi coordinates in the proper detector frame, involving gravitoelectric and gravitomagnetic fields. We calculate the displacements produced by gravitational waves up to second order in the distance parameter using this approach, and emphasize the significance of the gravitomagnetic contribution related to gravitational induction. Additionally, we demonstrate how this approach can be generalized to calculate displacements up to arbitrary order.
GENERAL RELATIVITY AND GRAVITATION
(2022)
Article
Astronomy & Astrophysics
Lorenzo Iorio, Matteo Luca Ruggiero
Summary: This study analytically calculates the effect of modified gravity models on the radial velocity of binary systems and specifically calculates the impact of the cosmological constant. The results show that the influence of the cosmological constant on the radial velocity of the Proxima/alpha Centauri AB binary system can be considered negligible.
Article
Astronomy & Astrophysics
Antonio Gallerati, Matteo Luca Ruggiero, Lorenzo Iorio
Summary: This paper examines the impact of the Standard Model Extension on the perturbation of radial velocity and suggests that suitable exoplanets' configurations and improvements in detection techniques may contribute to obtaining new constraints on the model parameters.
Article
Physics, Multidisciplinary
Matteo Luca Ruggiero
Summary: In this study, the authors utilize Fermi coordinates to analyze the interaction between a plane gravitational wave and a proper detector frame. They emphasize the analogy between the effects of the gravitational wave and the electromagnetic field, particularly in terms of a Lorentz-like force equation. The authors focus on the impact of the wave on time measurements and evaluate its magnitude. Additionally, they calculate the expression of the local spacetime metric in cylindrical coordinates and explore its relevance to the helicity-rotation coupling.
EUROPEAN PHYSICAL JOURNAL PLUS
(2023)
Article
Astronomy & Astrophysics
Davide Astesiano, Matteo Luca Ruggiero
Summary: In this study, the gravitoelectromagnetic approach is used to investigate the impact of general relativity on galactic dynamics under the weak-field and slow-motion approximation. Contrary to expectations, a specific class of solutions for the gravitomagnetic field is shown to introduce non-negligible corrections to the Newtonian velocity profile. The origin and interpretation of these corrections are discussed, and explicit applications to various galactic models are provided.
Article
Astronomy & Astrophysics
Davide Astesiano, Matteo Luca Ruggiero
Summary: This study explores disk galaxies within the framework of general relativity, investigating the potential corrections to the purely Newtonian approach even in the low energy limit. By considering both low energy expansion and exact solutions, the connection between these different approaches is clarified. The analysis focuses on two different limits - gravitomagnetic analogy and strong gravitomagnetism - which show corrections of the same order as the Newtonian terms. The findings suggest a geometrical origin for a certain amount of dark matter effects, explaining the observed flat velocity profile without the need for dark matter contributions.
