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The macroscopic model for a neutron star (NS) as a liquid drop at the equilibrium is used to extend the Tolman-Oppenheimer-Volkoff (TOV) equations taking into account the gradient terms responsible for the system surface. The parameters of…

General Relativity and Quantum Cosmology · Physics 2025-10-07 A. G. Magner , S. P. Maydanyuk , A. Bonasera , H. Zheng , T. Depastas , A. I. Levon , U. V. Grygoriev

We consider a self-gravitating system consisting of perfect fluid with spherical symmetry. Using the general expression of entropy density, we extremize the total entropy $S$ under the constraint that the total number of particles is fixed.…

General Relativity and Quantum Cosmology · Physics 2015-05-30 Sijie Gao

Gravitational-wave observations of binary neutron-star (BNS) mergers have the potential to revolutionize our understanding of the nuclear equation of state (EOS) and the fundamental interactions that determine its properties. However,…

High Energy Astrophysical Phenomena · Physics 2024-06-03 Brendan T. Reed , Rahul Somasundaram , Soumi De , Cassandra L. Armstrong , Pablo Giuliani , Collin Capano , Duncan A. Brown , Ingo Tews

We apply the 1+1+2 covariant semi-tetrad approach to describe a general static and spherically symmetric relativistic stellar object which contains two fluids with anisotropic pressure. The corresponding Tolman-Oppenheimer-Volkoff equations…

General Relativity and Quantum Cosmology · Physics 2023-01-04 Nolene F. Naidu , Sante Carloni , Peter Dunsby

The TOV equations govern the radial evolution of pressure and energy density in static neutron stars (NSs) in hydrodynamical equilibrium. Using the reduced pressure and energy density with respect to the NS central energy density, the…

High Energy Astrophysical Phenomena · Physics 2025-03-19 Bao-Jun Cai , Bao-An Li

We construct spherically symmetric solutions to the Einstein-Euler equations, which give models of gaseous stars in the framework of the general theory of relativity. We assume a realistic barotropic equation of state. Equilibria of the…

Analysis of PDEs · Mathematics 2016-06-08 Tetu Makino

In this work, we systematically derive the Einstein field equations in general relativity and $f(\mathcal{R})$ gravity, the Tolman-Oppenheimer-Volkoff (TOV) equation, and the expressions for axial and polar Tidal Love Numbers (TLNs) for…

General Relativity and Quantum Cosmology · Physics 2023-06-14 Pinaki Roy , Bharat Kumar

For a static, perfect fluid sphere with a general equation of state, we obtain the relativistic equation of hydrostatic equilibrium, namely the Tolman-Oppenheimer-Volkov equation, as the thermodynamical equilibrium in the microcanonical, as…

General Relativity and Quantum Cosmology · Physics 2013-05-14 Zacharias Roupas

We present new analytic solutions to the relativistic Boltzmann equation within the relaxation time approximation. We first obtain spherically expanding solutions which are the kinetic counterparts of the exact solutions of the…

High Energy Physics - Theory · Physics 2015-04-22 Yoshitaka Hatta , Mauricio Martinez , Bo-Wen Xiao

We present a derivation of the mechanics of isothermal gas spheres directly from the Vlasov--Poisson equation. By extremising the Boltzmann entropy, we obtain the Maxwell--Boltzmann distribution for a self-gravitating isothermal Newtonian…

Astrophysics of Galaxies · Physics 2025-11-13 Steven D Miller

The phenomenon of quantum vacuum polarization in the presence of a gravitational field is well understood and is expected to have a physical reality, but studies of its back-reaction on the dynamics of spacetime are practically non-existent…

General Relativity and Quantum Cosmology · Physics 2018-02-08 Raúl Carballo-Rubio

We provide a set of general tools to study the problem of stellar equilibrium in any gravitational theory in which spherically symmetric spacetimes satisfy master field equations taking the form of an equality between an identically…

General Relativity and Quantum Cosmology · Physics 2026-03-26 Julio Arrechea , Raúl Carballo-Rubio , Matt Visser

We investigate relativistic spherically symmetric static perfect fluid models in the framework of the theory of dynamical systems. The field equations are recast into a regular dynamical system on a 3-dimensional compact state space,…

General Relativity and Quantum Cosmology · Physics 2009-11-10 J. Mark Heinzle , N. Rohr , C. Uggla

Besides their astrophysical interest, compact stars also provide an arena for understanding the properties of theories of gravity that differ from Einstein's general relativity. Numerous studies have shown that different modified theories…

General Relativity and Quantum Cosmology · Physics 2015-08-05 Kostas Glampedakis , George Pappas , Hector O. Silva , Emanuele Berti

We revisit static, spherically symmetric perfect-fluid stellar models in General Relativity within the framework of the $1+1+2$ semi-tetrad formalism. For locally rotationally symmetric static spacetimes, the Tolman-Oppenheimer-Volkoff…

General Relativity and Quantum Cosmology · Physics 2026-05-27 Eduardo Bittencourt , Mariam Campbell , Peter K. S. Dunsby , Sergio E. Jorás

Static spherically symmetric perfect-fluid solutions of Einstein's equations play a central role in relativistic astrophysics and stellar structure theory. While many exact solutions satisfy Einstein's equations mathematically, only a…

General Relativity and Quantum Cosmology · Physics 2026-05-22 Dina Demissenova , Nurzada Beissen , Kuantay Boshkayev , Hernando Quevedo

In this article we perform a detailed theoretical analysis for a class of new exact solutions with anisotropic fluid distribution of matter for compact objects in hydrostatic equilibrium. To achieve this we call the relation between the…

General Relativity and Quantum Cosmology · Physics 2018-05-10 S. K. Maurya , Ayan Banerjee , Phongpichit Channuie

Dev (2002) discussed some exact solutions of anisotropic stars for special forms of TOV for constant energy density. Considering Bijalwan (2011) ansatz for charged perfect fluids we present here some exact solutions to the generalized TOV…

General Physics · Physics 2011-09-26 Naveen Bijalwan

We study the Tolman-Oppenheimer-Volkoff equation in the presence of a cosmological constant for general thermodynamically consistent equations of state, without imposing regularity at the center. Formulating the problem as an initial value…

General Relativity and Quantum Cosmology · Physics 2026-04-16 Christos Dounis , Charis Anastopoulos

Stars are essentially gravitationally stabilised thermonuclear reactors in hydrostatic equilibrium. The fundamental differential equation for all Newtonian gaseous stars in equilibrium is \begin{align}…

General Relativity and Quantum Cosmology · Physics 2021-09-07 Steven D Miller