Article
Physics, Multidisciplinary
Wentao Liu, Xiongjun Fang, Jiliang Jing, Anzhong Wang
Summary: This paper explores the gauge choices in general spherically symmetric spacetimes and constructs the gauge invariant variables and master equations for both the Detweiler easy gauge and the Regge-Wheeler gauge. It also investigates the particular cases for l = 0,1. The results provide analytical calculations of metric perturbations in general spherically symmetric spacetimes and can be applied to various cases, including the effective-one-body problem.
SCIENCE CHINA-PHYSICS MECHANICS & ASTRONOMY
(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
Astronomy & Astrophysics
Michele Lenzi, Carlos F. Sopuerta
Summary: The perturbation theory of vacuum spherically symmetric spacetimes allows for an expansion of perturbations in scalar, vector, and tensor harmonics, with decoupled perturbative equations for modes with different parity and harmonic numbers. The most general master function for each parity is a linear combination of specific master functions, satisfying wave equations with potential. The study reveals two branches of solutions for each parity, one containing known master functions and the other including new master functions and an infinite collection of potentials leading to independent master functions.
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
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
Materials Science, Multidisciplinary
Avik De, Simran Arora, Uday Chand De, P. K. Sahoo
Summary: The article first investigates the geometrical structures of a pseudo-symmetric spacetime under the condition of conformal flatness, and then further studies the spacetime solutions of F(R)-gravity theory and their relationships with cosmological effects.
RESULTS IN PHYSICS
(2022)
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
Astronomy & Astrophysics
Duo Li, Bin Wu, Zhen-Ming Xu, Wen-Li Yang
Summary: This study investigates the thermodynamic properties of a shell of bosons near the Schwarzschild black hole horizon using statistical mechanics, revealing Bose-Einstein condensation at non-zero temperatures in curved spacetimes. Additionally, the analysis of photon gas entropy near the black hole horizon exhibits an area dependence similar to the Bekenstein-Hawking entropy, offering new perspectives on black hole thermodynamics. These findings are extended to D + 1 dimensional spherically symmetric static spacetimes.
Article
Physics, Multidisciplinary
Z. Yousaf, M. Z. Bhatti, M. Rasheed
Summary: This manuscript constructs a spherical thin shell wormhole in the background of the minimally coupled f(R, T) model, using a cut and paste approach to link interior and exterior surfaces. The energy-momentum density and surface pressure for the f(R, T) = R + αR^2 + λT model are found using the Lanczos equation, and the dynamical behavior of the wormhole is checked using the polytropic equation of state. The stability of the constructed wormhole with throat radius a(0) is examined using a standard potential approach, with graphical analysis showing that stability regions depend on the specific values of the mass to charge ratio.
Article
Physics, Particles & Fields
Erickson Tjoa, Robert B. Mann
Summary: This study investigates the dynamics of an Unruh-DeWitt detector interacting with a massless scalar field in static spherically symmetric spacetimes, deriving specific physical insights and characteristics.
JOURNAL OF HIGH ENERGY PHYSICS
(2022)
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
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
Physics, Particles & Fields
Li-Ming Cao, Yong Song
Summary: In this study, a quasi-local definition of a photon sphere and photon surface in spherically symmetric spacetime is proposed, which effectively excludes photon surfaces in spacetime without gravity. By applying this definition to gravitational collapse models, analytic photon surface solutions in the Oppenheimer-Snyder model and reasonable numerical solutions for marginally bounded collapse in the LTB model are found. Interestingly, the time difference between the occurrence of the photon surface and the event horizon in the OS model is mainly determined by the total mass of the system rather than the size or strength of the gravitational field of the system.
EUROPEAN PHYSICAL JOURNAL C
(2021)
Article
Astronomy & Astrophysics
S. Oghbaiee, N. Rahmanpour, H. Shojaie
Summary: In this paper, we study the nearly flat approximation of a conformally invariant gravitational theory in metric measure space (MMS) and investigate the transformation of the energy-momentum tensor in this context. We obtain the vacuum solution of MMS and its weak field limit in the spherically symmetric coordinates. It is shown that when restricted to the framework of general relativity, the vacuum solution can simulate dark matter by employing a density function which is an essential part of MMS. We derive an equation for the density function for a general profile of a rotation curve obtained from observations and provide the density functions corresponding to two well-known profiles PSS and NFW.
PHYSICS OF THE DARK UNIVERSE
(2023)