Article
Physics, Multidisciplinary
Amir H. Rezaei, T. Azizi, N. Rashidi
Summary: In this paper, an exponential form of modified gravity is considered. The theory is consistent with local tests and various aspects of the model are investigated, including the static solution, scalar field potential, and stability of critical points. The realization of inflation and its graceful exit in this model are also studied.
Article
Physics, Mathematical
Allah Ditta, Tiecheng Xia
Summary: The commitment of this work is to find solutions for compact stellar models using the spherically symmetric static space-time and anisotropic matter distribution in the framework of f(T, T) gravity. The authors used specific metric functions and evaluated their solutions based on the Karmarkar condition. By incorporating observational data, they demonstrate the graphical fit and physical admissibility of their solutions.
INTERNATIONAL JOURNAL OF GEOMETRIC METHODS IN MODERN PHYSICS
(2022)
Article
Astronomy & Astrophysics
Aylin Caliskan, Rana Muhammad Zulqarnain, Ertan Gudekli, Imran Siddique, Hijaz Ahmad, Sameh Askar
Summary: This paper explores new neutron star models based on spherically symmetric space-time using f(T,T) gravity theory. By incorporating off-diagonal tetrad and employing junction equations, the properties of compact stars are investigated thoroughly, including energy density, pressure profiles, anisotropy, equation of state, and stability.
FRONTIERS IN ASTRONOMY AND SPACE SCIENCES
(2023)
Article
Physics, Multidisciplinary
J. K. Singh, Akanksha Shaily, Akanksha Singh, Aroonkumar Beesham, Hamid Shabani
Summary: We investigate the realization of a bounce in the framework of higher order curvature in f(R, T) modified theory of gravity. Our analysis focuses on explaining the contraction phase, bounce phase, and expansion phase using cosmological parameters. We find a violation of the null energy condition, model instability, and a singularity at the bouncing point, supporting the concept of a bouncing cosmology. The equation of state parameter exhibits a ghost condensate behavior near the bouncing point. Additionally, we discuss the stability of the model through linear perturbations in the Hubble parameter and energy density.
Article
Physics, Multidisciplinary
Riaz Ahmed, G. Abbas, Ertan Gudekli
Summary: This study investigates the dissipative gravitational collapse of an anisotropic spherically symmetric radiating star in f(R, T) gravity, while confirming the well-behaved energy conditions and other physical properties in the background of f(R, T) theory. The results of the model are consistent with General Relativity when the parameter lambda is set to zero.
CHINESE JOURNAL OF PHYSICS
(2021)
Article
Physics, Particles & Fields
Sebastian Bahamonde, Konstantinos F. Dialektopoulos, Manuel Hohmann, Jackson Levi Said, Christian Pfeifer, Emmanuel N. Saridakis
Summary: This study focuses on the cosmological perturbation theory in f(T) gravity, which is a simple extension of the teleparallel equivalent of general relativity. The authors examine the possibility of a non-flat FLRW background solution and perform perturbations for different spatial geometries. They determine the behavior of the perturbative modes in this non-flat FLRW setting for arbitrary f(T) models and identify propagating modes.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Physics, Particles & Fields
Ji-Yu Cheng
Summary: This paper provides a straightforward proof of the validity of Birkhoff's theorem in modified teleparallel equivalent theories of gravity, which states that if the matter distribution is spherically symmetric, then the spacetime is static in a region where t remains timelike and (r, theta, phi) stay spacelike. This version of Birkhoff's theorem is rather trivial. The theorem also reveals that the gravitational field of a spherically symmetric distribution of matter and of the spherically symmetric vacuum spacetime are both static in modified teleparallel equivalent theories of gravity.
EUROPEAN PHYSICAL JOURNAL C
(2023)
Article
Astronomy & Astrophysics
A. Chanda, S. Dey, B. C. Paul
Summary: Investigated wormhole solutions obtained by Morris and Thorne in general relativity in a modified theory of gravity, considering the role of coupling parameters in determining the matter composition and existence of the wormholes.
GENERAL RELATIVITY AND GRAVITATION
(2021)
Article
Multidisciplinary Sciences
Polina Petriakova, Arkady Popov, Sergey Rubin
Summary: Studying the evolution of the Universe from sub-Planckian scale to present times reveals the requirement for exponential expansion of space and significant restrictions on parameter values of a function f(R). The initial metric of the Universe is assumed to be maximally symmetric with positive curvature.
Article
Astronomy & Astrophysics
Santosh V. Lohakare, Francisco Tello-Ortiz, S. K. Tripathy, B. Mishra
Summary: In this paper, the bouncing behavior of cosmological models in the background of the Hubble function in the F(R,G) theory of gravity was studied. It was found that both models satisfy the bouncing cosmological properties and exhibit accelerating behavior at the late evolution time. The results of this study are of great significance for understanding cosmic evolution and solving cosmological problems.
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, Nuclear
Juan M. Z. Pretel, Takol Tangphati, Ayan Banerjee, Anirudh Pradhan
Summary: Recent advances in nuclear theory and astrophysical observations have raised the need for specific theoretical models to study dense-matter physics phenomena. This study explores the structure of compact stars composed of a charged perfect fluid in the context of f (R,T) gravity, considering the existence of non-nucleonic degrees of freedom predicted by quantum chromodynamics (QCD).
Article
Physics, Nuclear
Aaqid Bhat, Sanjay Mandal, P. K. Sahoo
Summary: This study explores the concept of cosmological inflation within the framework of (T, T) theory of gravity and assesses the feasibility of the models through numerical analysis.
Article
Astronomy & Astrophysics
Takol Tangphati, Sudan Hansraj, Ayan Banerjee, Anirudh Pradhan
Summary: Recent advances in instrumentation and computational methods have led to increased interest in studying the properties of nuclear matter under extreme conditions and the core of neutron stars. By analyzing the observations of pulsars, we investigated compact static configurations composed of interacting quark matter and derived conclusions that provide a more efficient explanation for the observational facts.
PHYSICS OF THE DARK UNIVERSE
(2022)
Article
Astronomy & Astrophysics
Archana Dixit, Anirudh Pradhan
Summary: This study investigates the impact of bulk viscosity in the framework of f(T,B) gravity and constrains the model parameters using observational data. The results show that the model is in good agreement with the observations. In addition, the evaluation of the effective viscous equation of state parameter and the analysis of different energy conditions suggest that the model is valid and stable, but the universe is expanding faster.