Relativistic modelling of a superdense star containing a charged perfect fluid (original) (raw)
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International Journal of Theoretical Physics, 2014
We present a spherically symmetric solution of the general relativistic field equations in isotropic coordinates for perfect charged fluid, compatible with a super dense star modeling. The solution is well behaved for all the values of Schwarzschild parameter u lying in the range 0 < u < 0.1727 for the maximum value of charge parameter K = 0.08163. The maximum mass of the fluid distribution is calculated by using stellar surface density as µ Σ = 4.6888 × 10 14 g cm −3 . Corresponding to K = 0.08 and u max = 0.1732, the resulting well behaved solution has a maximum mass M = 0.9324M and radius R = 8.00 and by assuming µ Σ = 2 × 10 14 g cm −3 the solution results a stellar configuration with maximum mass M = 1.43M and radius R = 12.25 km. The maximum mass is found increasing with increasing K up to 0.08. The well behaved class of relativistic stellar models obtained in this work might has astrophysical significance in the study of internal structure of compact star such as neutron star or self-bound strange quark star like Her X-1.
Applied Mathematics and Computation, 2012
We have obtained a variety of well behaved classes of Charge Analogues of Heintzmann's [1] solution by using a particular electric intensity, which depends upon two parameter K and n. These solutions describe charged fluid balls with positively finite central pressure, positively finite central density; their ratio is less than one and causality condition is obeyed at the centre. The outmarch of pressure, density, pressure-density ratio and the adiabatic speed of sound is monotonically decreasing, however, the electric intensity is monotonically increasing in nature. These solutions give us wide range of parameter K for every positive value of n for which the solution is well behaved hence, suitable for modeling of super dense stars like neutron stars and pulsars. Keeping in view of well behaved nature of these solutions, one new class of solutions is being studied extensively. Moreover, this class of solutions gives us wide range of constant K (1.3 6 K 6 17.95). Also this class of solutions, the mass of a star is maximized with all degree of suitability, compatible with neutron stars and pulsars. By assuming the surface density q b = 2 Â 10 14 g/cm 3 , the whole family of charged solution with well behaved conditions, the maximum mass and corresponding radius is 4.5132M H and 16.9057 km respectively.
The European Physical Journal C, 2015
In this work some families of relativistic anisotropic charged fluid spheres have been obtained by solving the Einstein-Maxwell field equations with a preferred form of one of the metric potentials, and suitable forms of electric charge distribution and pressure anisotropy functions. The resulting equation of state (EOS) of the matter distribution has been obtained. Physical analysis shows that the relativistic stellar structure for the matter distribution considered in this work may reasonably model an electrically charged compact star whose energy density associated with the electric fields is on the same order of magnitude as the energy density of fluid matter itself (e.g., electrically charged bare strange stars). Furthermore these models permit a simple method of systematically fixing bounds on the maximum possible mass of cold compact electrically charged self-bound stars. It has been demonstrated, numerically, that the maximum compactness and mass increase in the presence of an electric field and anisotropic pressures. Based on the analytic models developed in this present work, the values of some relevant physical quantities have been calculated by assuming the estimated masses and radii of some well-known potential strange star candidates like
A perfect fluid model for compact stars
Canadian Journal of Physics
In the framework of Einstein's theory of general relativity we present a new interior solution with a perfect fluid, this is constructed from the proposal of a gravitational redshift factor. The geometry is regular and density and pressure are monotonic decrescent functions, furthermore the sound speed is smaller than the light speed and monotonic crescent. The solution depends on a parameter w ∈ (0, 2.0375509325] related to the compactness of the star u = GM/c 2 R, the maximum value u = 0.2660858316 which allow to describe compact stars like quark stars or neutron stars. Although there is a diversity of stars for which the model can be used, we only apply this solution to describe the interior of a neutron star PSR J0348+0432. According to the observations, it is known that its mass M = (2.01 ± 0.04)M and its radius is between 12, 062Km and 12, 957Km, so the value of the compactness is in the range u ∈ [0.2244845, 0.2509338]. In addition to the decreasing behavior of the mentioned pressure and density functions, the results are consistent with the density values range typical of neutron stars and the maximal central density of the star result to be 1.283818 × 10 18 Kg/m 3 .
2014
In this work some families of relativistic anisotropic charged fluid spheres have been obtained by solving Einstein-Maxwell field equations with the preferred form of one of the metric potentials, a suitable forms of electric charge distribution and pressure anisotropy functions. The resulting equation of state (EOS) of the matter distribution has been obtained. Physical analysis shows that the relativistic stellar structure for matter distribution obtained in this work may reasonably model an electrically charged compact star whose energy density associated with the electric fields is on the same order of magnitude as the energy density of fluid matter itself (e.g. electrically charged bare strange stars). These models permit a simple method of systematically fixing bounds on the maximum possible mass of cold compact electrically charged self-bound stars. It has been demonstrated numerically that the maximum compactness and mass increase in the presence of electric field and anisotropic pressures. Based on the analytic model developed in this present work, the values of the relevant physical quantities have been calculated by assuming the estimated masses and radii of some well known potential strange star candidates like PSR
The physical properties of an analytic model for a relativistic star
Astrophysics and Space Science, 1989
An exact solution of Einstein's equations for a static isentropic perfect fluid sphere is examined in detail. The analysis yields a strong indication that the model isstable with respect to infinitesimal radial pulsations. This means that the temperature is decreasing outwards. We prove that the adiabatic speed of sound is everywhere less than the speed of light if and only if the radius of the sphere is larger than 1.61 times its Schwarzschild radius. We further show that the strong energy condition is fulfilled everywhere if and only if the radius is larger than 1.76 times the Schwarzschild radius. The necessary and sufficient condition for the speed of sound to be decreasing outwards is given, and we find that this criterion is fulfilled if the fluid is causal. Taking the values of the pressure ρ and the density ρ to be somewhere given by the maximum values from Baymet al.'s equation of state, i.e., ρ0=5.1×1014 g cm−3 andp 0=7.4×1033 dyne cm−2, we find the maximum mass of the fluid sphere to be 2.5 solar masses.
A Spherical Relativistic Anisotropic Compact Star Model
International Journal of Astronomy and Astrophysics, 2018
We provide solutions to Einsteins field equations for a model of a spherically symmetric anisotropic fluid distribution, relevant to the description of compact stars. The central matter-energy density, radial and tangential pressures, red shift and speed of sound are positive definite and are decreasing monotonically with increasing radial distance from the center of matter distribution of astrophysical object. The causality condition is satisfied for complete fluid distribution. The central value of anisotropy is zero and is increasing monotonically with increasing radial distance from the center of the distribution. The adiabatic index is increasing with increasing radius of spherical fluid distribution. The stability conditions in relativistic compact star are also discussed in our investigation. The solution is representing the realistic objects
A static spherically symmetric perfect fluid solution to model the interior of stars
Revista Mexicana de Física
An exact solution for modeling the interior of stars with perfect fluid is presented, the geometry of their interior is described by a static and spherically symmetric regular space-time. The hydrostatic functions are physically acceptable for the compactness rate u = GM/c2R ∈ (0, 0.3183497], the speed of sound is a monotonically decreasing function, positive and lower than the speed of light, which implies that the condition of causality is not violated, meanwhile the stability of the solution is guaranteed due to the adiabatic index γ > 3.08387 and it is a monotonically increasing function. The analysis of the solution is presented graphically for specific values of the compactness on the interval u ∈ [0.2509338, 0.3183497] with the minimum value of this interval associated to the neutron star PSR J0348+0432, for observational data which generates the maximum compactness when the radius is minimal R = 12.062 km and the mass is maximum M = 2.05 M¯, generating a value of the cent...
Relativistic strange stars with charged anisotropic matter
arXiv: General Relativity and Quantum Cosmology, 2017
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 metric functions, namely, embedding class one condition. The investigation is carried out by generalising the properties of a spherical star with an emphasis on hydrostatic equilibrium equation, i.e., the generalised Tolman-Oppenheimer-Volkoff equation, in our understanding of these compact objects. We match the interior solution to an exterior Reissner-Nordstrom solution, and study some physical features of this models, such as the energy conditions, speeds of sound, and mass - radius relation of the star. We also show that obtained solution is compatible with observational data for compact object Her X-1.
Relativistic Charged Star Solutions in Higher Dimensions
International Journal of Theoretical Physics, 2013
We present a class of relativistic solutions of the Einstein-Maxwell equations for a spherically symmetric charged static fluid sphere in higher dimensions. The interior space at t = constant considered here possess (D − 1) dimensional spheroidal geometry described by a higher dimensional Vaidya-Tikekar metric. A class of new static solutions of coupled Einstein-Maxwell equations is obtained in a D-dimensional space-time by prescribing the geometry of a (D − 1) dimensional hyper spheroid in hydrostatic equilibrium. The solutions of the Einstein-Maxwell field equations are employed to obtain relativistic models for charged compact stars with a suitable law for variation of electric field in terms of the charged fluid content in the interior of the sphere. The central density is found to depend on the space-time dimensions and a physically realistic model is permitted for (D ≥ 4). The validity of both Strong Energy Condition (SEC), Weak Energy Condition (WEC) are studied for a given configuration and compactness of compact objects. We found new class of solutions with interesting stellar models where it permits a star with a core having different property than the rest which however disappears in higher dimensions. The effect of dimensions on the Electric charge of the compact object is studied. We note that the upper limit of the electric field is determined by the space-time dimensions which are determined.