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We derive all contributions to the dispersion measure (DM) of electromagnetic pulses to linear order in cosmological perturbations, including both density fluctuations and relativistic effects. We then use this result to calculate the power…

Cosmology and Nongalactic Astrophysics · Physics 2021-06-30 David Alonso

The specific astrophysical data collected during the last decade causes the need for the modification of the expression for the Einstein-Hilbert action, and several attempts sufficing this need are known. The modification suggested in this…

General Relativity and Quantum Cosmology · Physics 2012-07-04 Sergey Siparov , Nicoleta Brinzei

We present a class of exact solutions of Einstein's gravitational field equations describing spherically symmetric and static anisotropic stellar type configurations. The solutions are obtained by assuming a particular form of the…

General Relativity and Quantum Cosmology · Physics 2017-10-04 T. Harko , M. K. Mak

We present model for anisotropic compact star under the general theory of relativity of Einstein. In the study a 4-dimensional spacetime has been considered which is embedded into the 5-dimensional flat metric so that the spherically…

General Physics · Physics 2018-08-01 S. K. Maurya , Saibal Ray , Shounak Ghosh , Sarbajit Manna , Smitha T. T

We model a charged anisotropic relativistic star with a quadratic equation of state. Physical features of an exact solution of the Einstein-Maxwell system are studied by incorporating the effect of the nonlinear term from the equation of…

General Relativity and Quantum Cosmology · Physics 2015-06-23 P. Mafa Takisa , S. D. Maharaj , Subharthi Ray

In this work, we have made a systematic study of how the gravitational wave frequency of the fundamental mode from compact stars is affected by anisotropic effects using realistic equations of state. Our study is an extension of the seminal…

General Relativity and Quantum Cosmology · Physics 2024-03-19 Elvis J. Aquino Curi , Luis B. Castro , Cesar V. Flores , César H. Lenzi

This paper uses the definition of complexity for a static spherically symmetric spacetime and extends it to the case of charged distribution. We formulate the Einstein-Maxwell field equations corresponding to the anisotropic interior and…

General Relativity and Quantum Cosmology · Physics 2023-06-02 M. Sharif , Tayyab Naseer

By means of numerical simulations we study the radial-orbit instability in anisotropic self-gravitating $N-$body systems under the effect of noise. We find that the presence of additive or multiplicative noise has a different effect on the…

Astrophysics of Galaxies · Physics 2022-06-08 Pierfrancesco Di Cintio , Lapo Casetti

Unimodular gravity provides a theoretical framework that allows for non-conservation of energy-momentum, with possible implications for the cosmological constant problem. It is then important to study the predictions of unimodular gravity…

General Relativity and Quantum Cosmology · Physics 2019-09-11 J. A. Astorga-Moreno , Javier Chagoya , J. C. Flores-Urbina , Miguel A. Garcia-Aspeitia

We introduce a new type of generating theorems in General Relativity for anisotropic, static, spherically symmetric solutions of the Einstein field equations. The results are used to derive a class of solutions that can serve as new models…

General Relativity and Quantum Cosmology · Physics 2026-04-14 Paulo Luz , Sante Carloni

Using the Bower-Liang model, we discuss how pressure anisotropies affect the microscopic and macroscopic properties of hybrid stars. We find that anisotropies affect the maximum mass, central density, and radius of the canonical stars.…

High Energy Astrophysical Phenomena · Physics 2024-10-16 Luiz L. Lopes , H. C. Das

Non-radial oscillation modes of a neutron star possess valuable information about its internal structure and nuclear physics. Starting from the quadrupolar order, such modes under general relativity are known as quasi-normal modes since…

General Relativity and Quantum Cosmology · Physics 2024-11-22 Shu Yan Lau , Siddarth Ajith , Victor Guedes , Kent Yagi

The anisotropic influence on the $f$-mode frequency of oscillations and dimensionless tidal deformability of neutron stars is analyzed by employing the nonradial oscillation equations for the complete general relativity frame and tidal…

General Relativity and Quantum Cosmology · Physics 2026-05-27 José D. V. Arbañil , Gabriel O. Cavalheiro , Victor B. T. Alves , Juan M. Z. Pretel , César O. V. Flores , César H. Lenzi

We study the propagation of the quantum field perturbations in the interior of the Schwarzschild black hole. The interior of the black hole is like an anisotropic cosmological background which expands in one extended direction while…

General Relativity and Quantum Cosmology · Physics 2024-06-28 Hassan Firouzjahi

We obtain a class of anisotropic spherically symmetric relativistic solutions of compact objects in hydrostatic equilibrium in the $f(R,T) =R+2\chi T$ modified gravity, where $R$ is the Ricci scalar, $T$ is the trace of the energy momentum…

General Physics · Physics 2020-09-18 S. Dey , A. Chanda , B. C. Paul

We study the spectra generated as a result of bulk Comptonization by relativistic electrons in radial flows onto compact objects. We solve numerically the general-relativistic radiative transfer equation in the Schwarzschild spacetime, in…

Astrophysics · Physics 2007-05-23 H. Papathanassiou , D. Psaltis

The divergence of the momentum density field of the large scale structure generates a secondary anisotropy contribution to the Cosmic Microwave Background (CMB). While the effect is best described as a non-linear extension to the well-known…

Astrophysics · Physics 2009-11-13 Asantha Cooray , Naoki Seto

We show that the difference between the theoretically expected and measured by WMAP amplitude of the quadrupole fluctuations of CMB can be related to the impact of the anisotropic curvature of the homogeneous universe dominated by the dark…

Astrophysics · Physics 2008-11-26 M. Demiański , A. G. Doroshkevich

In this investigation we examine the astrophysical consequences of the influence of pressure anisotropy on the physical properties of observed pulsars within the background of $f(Q,T)$ gravity by choosing a specific form $f(Q, T)=\psi_1\, Q…

General Relativity and Quantum Cosmology · Physics 2025-10-08 S. K. Maurya , Abdul Aziz , Ksh. Newton Singh , G. Mustafa , Y. Sekhmani , Saibal Ray

In this paper, we shall consider spherically symmetric spacetime solutions describing the interior of stellar compact objects, in the context of higher-order curvature theory of the f(R) type. We shall derive the non--vacuum field equations…

General Relativity and Quantum Cosmology · Physics 2021-06-28 G. G. L. Nashed , S. D. Odintsov , V. K. Oikonomou