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For a static, spherically symmetric perfect fluid, the hydrostatic equilibrium condition is expressed by the Tolman-Oppenheimer-Volkoff (TOV) equation, which relates the pressure gradient to the enclosed mass and the local energy density. Its derivation follows from the Einstein field equations for a perfect fluid source, and the Newtonian limit is recovered when the relativistic corrections become negligible.
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Card 1 · Stellar equilibrium configurations of compact stars in f ( R , T ) theory of gravity
In this article we study the hydrostatic equilibrium configuration of neutron stars and strange stars, whose fluid pressure is computed from the equations of state p =ωρ 5/3 and p =0.28(ρ−4ℬ), respectively, with ω and ℬ being constants and ρ the energy density of the fluid. We start by deriving the…
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In this article we study the hydrostatic equilibrium configuration of neutron stars and strange stars, whose fluid pressure is computed from the equations of state p =ωρ 5/3 and p =0.28(ρ−4ℬ), respectively, with ω and ℬ being constants and ρ the energy density of the fluid. We start by deriving the hydrostatic equilibrium equation for the f ( R , T ) theory of gravity, with R and T standing for the Ricci scalar and trace of the energy-momentum tensor, respectively. Such an equation is a generalization of the one obtained from general relativity, and the latter can be retrieved for a certain limit of the theory. For the f ( R , T )= R +2λ T functional form, with λ being a constant, we find that some physical properties of the stars, such as pressure, energy density, mass and radius, are affected when λ is changed. We show that for a fixed central star energy density, the mass of neutron and strange stars can increase with λ. Concerning the star radius, it increases for neutron stars and …
Card 2 · Role of pressure anisotropy on relativistic compact stars
We investigate a compact spherically symmetric relativistic body with anisotropic particle pressure profiles. The distribution possesses characteristics relevant to modeling compact stars within the framework of general relativity. For this purpose, we consider a spatial metric potential of Korkina…
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We investigate a compact spherically symmetric relativistic body with anisotropic particle pressure profiles. The distribution possesses characteristics relevant to modeling compact stars within the framework of general relativity. For this purpose, we consider a spatial metric potential of Korkina and Orlyanskii [Ukr. Phys. J. 36, 885 (1991)] type in order to solve the Einstein field equations. An additional prescription we make is that the pressure anisotropy parameter takes the functional form proposed by Lake [Phys. Rev. D 67, 104015 (2003)]. Specifying these two geometric quantities allows for further analysis to be carried out in determining unknown constants and obtaining a limit of the mass-radius diagram, which adequately describes compact strange star candidates like Her X-1 and SMC X-1. Using the anisotropic Tolman-Oppenheimer-Volkoff equations, we explore the hydrostatic equilibrium and the stability of such compact objects. Then, we investigate other physical features of t …
Card 3 · Thermodynamical instabilities of perfect fluid spheres in General Relativity
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 well as the canonical, ensemble. We find that the stability…
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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 well as the canonical, ensemble. We find that the stability condition determined by the second variation of entropy coincides with the dynamical stability condition derived by variations to first order in the dynamical Einstein's equations. Thus, we show the equivalence of microcanonical thermodynamical stability with linear dynamical stability for a static, spherically symmetric field in General Relativity. We calculate the Newtonian limit and find the interesting property, that the microcanonical ensemble in General Relativity transforms to the canonical ensemble for non-relativistic dust particles. Finally, for specific kinds of systems, we study the effect of the cosmological constant to the microcanonical thermodynamical stability of fluid sphe …
Card 4 · HYDROSTATIC EQUILIBRIUM OF INSULAR, STATIC, SPHERICALLY SYMMETRIC, PERFECT FLUID SOLUTIONS IN GENERAL RELATIVITY
An analysis of insular solutions of Einstein's field equations for static, spherically symmetric, source mass, on the basis of exterior Schwarzschild solution is presented. Following the analysis, we demonstrate that the regular solutions governed by a self-bound (that is, the surface density does n…
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An analysis of insular solutions of Einstein's field equations for static, spherically symmetric, source mass, on the basis of exterior Schwarzschild solution is presented. Following the analysis, we demonstrate that the regular solutions governed by a self-bound (that is, the surface density does not vanish together with pressure) equation of state (EOS) or density variation cannot exist in the state of hydrostatic equilibrium, because the source mass which belongs to them, does not represent the "actual mass" appears in the exterior Schwarzschild solution. The only configuration which could exist in this regard is governed by the homogeneous density distribution (i.e. the interior Schwarzschild solution). Other structures which naturally fulfill the requirement of the source mass, set up by exterior Schwarzschild solution (and, therefore, can exist in hydrostatic equilibrium) are either governed by gravitationally-bound regular solutions (i.e. the surface density also vanishes togeth …
Card 5 · Complexity factor for anisotropic source in non-minimal coupling metric f(R) gravity
In this outline we recognize the idea of complexity factor for static anisotropic self-gravitating source with generalized f(R) metric gravity theory. In present consideration, we express the Einstein field equations, hydrostatic equilibrium equation, the mass function and physical behavior of f(R)…
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In this outline we recognize the idea of complexity factor for static anisotropic self-gravitating source with generalized f(R) metric gravity theory. In present consideration, we express the Einstein field equations, hydrostatic equilibrium equation, the mass function and physical behavior of f(R) model by using some observational data of well known compact stars like $$4U~1820-30, SAX~J1808.4-3658$$ and $$Her~X-1$$ . We define the scalar functions through the orthogonal splitting of the Reimann-Christofell tensor and then find the vanishing complexity condition for self-gravitating system with the help of these scalars. It has been found that the vanishing condition for the complexity are pressure anisotropy and energy density inhomogeneity must cancel each other. Moreover, we study the momentous results of an astral object for the vanishing of complexity factor. Finally, these solutions reduced to previous investigation about complexity factor in General Relativity by taking $$\lamb …
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Card 3 · terminology
Affected output: the Tolman-Oppenheimer-Volkoff (TOV) equation
Model explanation: This row supplied the field-native naming of the relativistic hydrostatic equilibrium equation as the Tolman-Oppenheimer-Volkoff equation, which the draft's earlier prose referred to only as the TOV equation without spelling it out.