Static Charged Fluid Research Articles

Static Charged Fluid Sphere in General Relativity

Static Charged Fluid Sphere in General Relativity

Charged strange star model in Tolman–Kuchowicz spacetime in the background of 5D Einstein–Maxwell–Gauss–Bonnet gravity

In this article, we provide a new model of static charged anisotropic fluid sphere made of a charged perfect fluid in the context of 5D Einstein–Maxwell–Gauss–Bonnet (EMGB) gravity theory. To generate exact solutions of the EMGB field equations, we utilize the well-behaved Tolman–Kuchowicz (TK) ansatz together with a linear equation of state (EoS) of the form p_r=beta rho -gamma , (where beta and gamma are constants). Here the exterior space-time is described by the EGB Schwarzschild metric. The Gauss–Bonnet Lagrangian term mathcal {L}_{GB} is coupled with the Einstein–Hilbert action through the coupling constant alpha . When alpha rightarrow 0, we obtain the general relativity (GR) results. Here we present the solution for the compact star candidate EXO 1785-248 with mass=(1.3 pm 0.2)M_{odot }; radius = 10_{-1}^{+1} km. respectively. We analyze the effect of this coupling constant alpha on the principal characteristics of our model, such as energy density, pressure components, anisotropy factor, sound speed etc. We compare these results with corresponding GR results. Moreover, we studied the hydrostatic equilibrium of the stellar system by using a modified Tolman–Oppenheimer–Volkoff (TOV) equation and the dynamical stability through the critical value of the radial adiabatic index.The mass-radius relationship is also established to determine the compactness factor and surface redshift of our model. In this way, the stellar model obtained here is found to satisfy the elementary physical requirements necessary for a physically viable stellar object.

Hyperbolically symmetric static charged cosmological fluid models

ABSTRACT In this work, the study on static fluid distributions under the influence of electromagnetism has been carried out with an emphasis on the hyperbolically symmetric metric. For this purpose, modified gravitational formulations in the presence of charge are used to calculate the effective energy–momentum tensor, which is then further refined by taking into account tetrad field components in the Minkowski coordinate system. Also, we compute the Tolman mass and a suitable formulation of the mass function. It exhibits that the hyperbolically symmetrical source has a negative effective matter density in all stellar formulations. This demonstrates that the quantum processes together with certain excessive constraints are deemed important to explain any physical implementations under the effects of the electromagnetic field. Additionally, we assessed the structure scalars and implemented the orthogonal splitting of the structure scalars and Riemann tensor in this modified gravity. Subsequently, various explicit precise cosmological solutions and their generating functions are developed.

Analytical studies on the hoop conjecture in charged curved spacetimes

Recently, with numerical methods, Hod clarified the validity of Thorne hoop conjecture for spatially regular static charged fluid spheres, which were considered as counterexamples against the hoop conjecture. In this work, we provide an analytical proof on Thorne hoop conjecture in the spatially regular static charged fluid sphere spacetimes.

Charged compact star model in Einstein-Maxwell-Gauss-Bonnet gravity

In this paper we present a model of a static charged anisotropic fluid sphere in the Einstein-Maxwell-Gauss-Bonnet (EMGB) theory of gravitation. We utilize the Krori-Barua (KB) ansatz together with a linear equation of state of the form \(p_{r}=\beta \rho -\gamma \) to generate exact solutions of the EMGB field equations describing compact objects. The model obtained here is found to satisfy the elementary physical requirements necessary for a physically realizable stellar object. We demonstrate that contributions from the Gauss-Bonnet terms have a nonzero impact on the density, pressure and anisotropy profiles. The vanishing of the electromagnetic field at the center of the stellar configuration leads to a relation between the equation of state parameter and the Gauss-Bonnet term. Our model reveals a direct connection between the nature of the matter configuration and higher dimensional effects.

Spherically Symmetric Static Charged Anisotropic Fluid in Rosen's Bimetric Theory of Gravitation

ABSTRACTIn this paper we have obtained an exact solution for the static spherically symmetric space-time with charged anisotropic fluid distribution in context of Rosen's Bimetric General Relativity (BGR).

Static charged fluid in (2 + 1)-dimensions admitting conformal Killing vectors

New solutions for (2 + 1)-dimensional Einstein–Maxwell spacetime are found for a static spherically symmetric charged fluid distribution with the additional condition of allowing conformal Killing vectors (CKV). We discuss physical properties of the fluid parameters. Moreover, it is shown that the model actually represents two structures, namely (i) Gravastar as an alternative of black hole and (ii) Electromagnetic Mass model depending on the nature of the equation of state of the fluid. Here the gravitational mass originates from electromagnetic field alone. The solutions are matched with the exterior region of the Bañados–Teitelboim–Zanelli (BTZ) type isotropic static charged black hole as a consequence of junction conditions. We have shown that the central charge density is dependent on the value of M0, the conserved mass of the BTZ black hole. This, in turn, depends on the black hole event horizon which again is related to the Hawking radiation temperature of a BTZ black hole. Thus, one may have a clue that the central charge density is related with Hawking radiation temperature of the BTZ black hole on the exterior region of the static charged fluid sphere.

ISOTROPIC CASES OF STATIC CHARGED FLUID SPHERES IN GENERAL RELATIVITY

In this paper we study the isotropic cases of static charged fluid spheres in general relativity. For this purpose we consider two different specializations and under these we solve the Einstein–Maxwell field equations in isotropic coordinates. The analytical solutions thus obtained are matched to the exterior Reissner–Nordström solutions which concern the values for the metric coefficients eν and eμ. We derive the pressure, density and pressure-to-density ratio at the center of the charged fluid sphere and boundary R of the star. Our conclusion is that static charged fluid spheres provide a good connection to compact stars.

Static charged fluid around a massive magnetic dipole

An analytical solution of Einstein-Maxwell equations with a static fluid as a source is presented. The spacetime is represented by the axially symmetric Weyl metric and the energy-momentum tensor describes a coupling of a fluid with an electromagnetic field. When appropriate limits are performed we recover the well-known solutions of Gutsunaev-Manko and Schwarzschild. Also, using Eckart's thermodynamics, we calculated the temperature, the mechanical pressure, the charge density, and the energy density of the system. The analysis of thermodynamic quantities suggests that the solution can be used to represent a magnetized compact stellar object surrounded by a charged fluid.

Static charged fluid around a magnetized mass

We show that any magnetostatic axially symmetric solution of the Einstein-Maxwell equations can be endowed with a specific charged fluid source of the Polanco et al. type via a simple procedure requiring the knowledge of exclusively the magnetostatic seed spacetime. Using this procedure we construct yet another exact solution for a massive magnetic dipole surrounded by a static charged fluid which is different from the Polanco et al. metric.

Tolman-Bayin type static charged fluid spheres in general relativity

In a static spherically symmetric Einstein–Maxwell space–time, the class of astrophysical solution found by Ray & Das and Pant & Sah are revisited here in connection to the phenomenological relationship between the gravitational and electromagnetic fields. It is qualitatively shown that the charged relativistic stars of Tolman and Bayin type are of purely electromagnetic origin. The existence of this type of astrophysical solutions is a probable extension of Lorentz's conjecture that an electron-like extended charged particle possesses only ‘electromagnetic mass’ and no ‘material mass’.

Static charged fluid surrounded by a black antihole: an enlarged Klein solution

A new Petrov type D exact solution of the Einstein-Maxwell equations with a charged perfect fluid is obtained from the seed Klein metric for a static spherically symmetric distribution of incoherent radiation. A special case of the new solution is studied in detail, its spacetime being found to possess one horizon inside which it is static. Since the fluid behaves acausally outside the horizon, the authors match their solution to a continuous set of electrovacuum spacetimes with cosmological terms (the cosmological constant Lambda depending on the junction radius). In the new spacetime, synchronous coordinates are constructed and a red-shift effect is evaluated.

Slowly rotating charged fluid spheres in general relativity.

The Einstein-Maxwell field equations for a charged perfect-fluid distribution in a stationary axisymmetric space-time are investigated. Under the assumption of slow rotation, these equations have been reduced to represent slowly rotating charged fluid spheres. It is observed that, similar to the case of slowly rotating uncharged fluid spheres, the field equations split into two parts: viz., the field equations for a static charged fluid sphere and the equations that determine the parameters \ensuremath{\omega} and \ensuremath{\Omega} which represent the angular velocity of the fluid distribution and the angular velocity of the inertial frames along the rotation axis, respectively.

A singularity-free solution for a static charged fluid sphere in Einstein–Cartan theory

A singularity-free solution for a static charged fluid sphere in the presence of spin density is obtained in Einstein–Cartan theory. It is shown that the solution satisfies physical conditions throughout the sphere.

A solution for a charged sphere in general relativity

In the present paper the field equations of general relativity have been solved to obtain a solution for a static charged fluid sphere. This solution is free from singularity and satisfies the necessary physical conditions.

A singularity-free solution for a charged fluid sphere in general relativity

A singularity-free solution was obtained for a static charged fluid sphere in general relativity. The solution satisfies physical conditions inside the sphere.

General-relativistic interior metric for a static charged fluid ball with pressure

General-relativistic interior metric for a static charged fluid ball with pressure

General-Relativistic Interior Metric for a Stable Static Charged Matter Fluid with Largeem

The general-relativistic field equations are solved for a spherically symmetric static charged matter fluid in isotropic coordinates, and matched at the boundary $R$ to the external Reissner-Nordstr\"om metric. No pressure, i.e., stress of undefined origin, is involved. There turns out to be one more unknown than equation, but consistency and continuity conditions severely restrict the solutions. It is found that the charged fluid can be in equilibrium even with a large $\frac{e}{m}$, such as for an electron considered as a fluid, but only if (1) there is a singularity in ${g}_{44}$ at $r=0$, (2) the matter density ${\ensuremath{\rho}}_{m}$ in the energy-momentum tensor is negative, and (3) the ratio $\frac{{\ensuremath{\rho}}_{e}}{{\ensuremath{\rho}}_{m}}$ of charge to matter density is a variable function. The energy density (as opposed to the matter density) can be made everywhere positive in the coordinates used. A simple picture of how the forces balance can be made.