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In the context of a family os scalar-tensor theories with a dynamical $\Lambda$, that is a binomial on the scalar field, the cosmological equations are considered. A general barotropic state equation $p=(\gamma-1)\rho$, for a perfect fluid…

General Relativity and Quantum Cosmology · Physics 2009-10-31 L. M. Diaz-Rivera , L. O. Pimentel

This paper explores the role of nonlinear electrodynamics on the stable configuration of thin-shell wormholes formulated from two equivalent geometries of Reissner-Nordstr\"om black hole with nonlinear electrodynamics. For this purpose, we…

General Relativity and Quantum Cosmology · Physics 2023-01-11 Faisal Javed , G. Fatima , G. Mustafa , Ali Ovgun

We present an equation of state for elastic matter which allows for purely longitudinal elastic waves in all propagation directions, not just principal directions. The speed of these waves is equal to the speed of light whereas the…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Max Karlovini , Lars Samuelsson

This paper is devoted to study cylindrically symmetric stellar filaments in self-interacting Brans-Dicke gravity. For this purpose, we construct polytropic filamentary models through generalized Lane-Emden equation in Newtonian regime. The…

General Physics · Physics 2016-06-22 M. Sharif , Rubab Manzoor

We consider cosmological solutions to general relativity with a single barotropic fluid, where the pressure is a general function of the density, $p = f(\rho)$. We derive conditions for static and oscillating solutions and provide examples,…

High Energy Physics - Theory · Physics 2015-12-31 John Kehayias , Robert J. Scherrer

Motion of two gravitating spherical stellar shells around a massive central body is considered. Each shell consists of point particles with the same specific angular momenta and energies. In the case when one can neglect the influence of…

Chaotic Dynamics · Physics 2009-11-10 M. V. Barkov , G. S. Bisnovatyi-Kogan , A. I. Neishtadt , V. A. Belinski

The equation of state (EoS) for neutron stars is a crucial topic in astrophysics, nuclear physics, and quantum chromodynamics (QCD), influencing their structure, stability, and observable properties. This review classifies EoS models into…

Nuclear Theory · Physics 2025-07-08 Zuhua Ji , Jiarui Chen , Yan Chen

We introduce two classes of spherically symmetric spacetimes having a thin shell of matter, in non-quadratic F(R) theories of gravity with non-constant scalar curvature R. In the first, the thin shell joins an inner region with an outer…

General Relativity and Quantum Cosmology · Physics 2020-10-07 Ernesto F. Eiroa , Griselda Figueroa-Aguirre

We study static, spherically symmetric neutron stars in a class of scalar-tensor theories with non-canonical kinetic terms (K-essence) obeying all causality and hyperbolicity conditions. These models have non-trivial dynamics that lead to a…

General Relativity and Quantum Cosmology · Physics 2025-09-12 Mark P. Hertzberg , Oleksandr S. Stashko

We study a spherical, self-gravitating fluid model, which finds applications in cosmic structure formation. We argue that since the system features nonlinearity and gravity-induced dispersion, the emergence of solitons becomes possible. We…

Pattern Formation and Solitons · Physics 2024-02-21 G. N. Koutsokostas , S. Sypsas , O. Evnin , T. P. Horikis , D. J. Frantzeskakis

In the era of gravitational wave astronomy, radial oscillations hold significant potential for not only uncovering the microphysics behind the internal structure but also investigating the stability of neutron stars (NSs). We start by…

Nuclear Theory · Physics 2026-02-02 Sayantan Ghosh , Sailesh Ranjan Mohanty , Tianqi Zhao , Bharat Kumar

The effects of the cosmological constant on the static equilibrium configurations and stability against small radial perturbations of relativistic polytropic spheres are investigated. This study numerically solves the hydrostatic…

General Relativity and Quantum Cosmology · Physics 2020-04-15 José D. V. Arbañil , Pedro H. R. S. Moraes

The aim of this paper is to discuss the theory of Newtonian and relativistic polytropes with generalized polytropic equation of state. For this purpose, we formulated the general framework to discuss the physical properties of polytrops…

General Physics · Physics 2016-06-22 M. Azam , S. A. Mardan , I. Noreen , M. A. Rehman

This paper develops a novel numerical method for obtaining structures of rapidly rotating stars based on a self-consistent field scheme. The solution is obtained iteratively. Both rapidly rotating barotropic and baroclinic equilibrium…

Solar and Stellar Astrophysics · Physics 2015-10-21 Kotaro Fujisawa

We report a new microscopic equation of state (EOS) of dense symmetric nuclear matter, pure neutron matter, and asymmetric and $\beta$-stable nuclear matter at zero temperature using recent realistic two-body and three-body nuclear…

High Energy Astrophysical Phenomena · Physics 2018-05-31 Ignazio Bombaci , Domenico Logoteta

The equilibrium configurations of slowly rotating anisotropic self-gravitating fluids are computed using the extended Hartle structure equations, including anisotropic effects, derived in our previous paper. We focus on the so-called…

General Relativity and Quantum Cosmology · Physics 2025-10-20 Philip Beltracchi , Camilo Posada

We construct the solutions of slowly rotating gravastars with a thin shell. In the zero-rotation limit, we consider the gravastar composed of a de Sitter core, a thin shell, and Schwarzschild exterior spacetime. The rotational effects are…

General Relativity and Quantum Cosmology · Physics 2016-01-13 Nami Uchikata , Shijun Yoshida

Heavy-neutrino (or neutralino) stars are studied using the general relativistic equations of hydrostatic equilibrium and the relativistic equation of state for degenerate fermionic matter. The Tolman-Oppenheimer-Volkoff equations are then…

Astrophysics · Physics 2009-10-30 Neven Bilic , Faustin Munyaneza , Raoul D. Viollier

Low surface brightness galaxies are an excellent laboratory where stars and baryonic matter act as tracers of the gravitational potential of the dark matter halo. If dark matter is modeled as a perfect fluid, then spherically symmetric and…

Astrophysics of Galaxies · Physics 2024-08-29 Andrés Aceña , Juan Barranco , Argelia Bernal , Ericson López , Mario Llerena

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