Anisotropic Fluid Star Model in Isotropic Coordinates

2020

Preprint

In this paper, we found a new model for compact star with charged anisotropic matter distribution considering an extended version of the Chaplygin equation of state. We specify a particular form of the metric potential Z(x) that allows us to solve the Einstein-Maxwell field equations. The obtained model satisfies all physical properties expected in a realistic star such that the expressions for the radial pressure, energy density, metric coefficients, measure of anisotropy and the mass are fully well defined and are regular in the interior of star. The solution obtained in this work can have multiple applications in astrophysics and cosmology.

Section: Introductionmentioning

confidence: 99%

A New Model for Charged Anisotropic Matter with Modified Chaplygin Equation of State

Malaver¹,

2020

Preprint

“…The existence of anisotropy within a star can be explained by the presence of a solid core, phase transitions, a type III super fluid, a pion condensation [28] or another physical phenomenon by the presence of an electrical field [29]. Many researchers have used a great variety of mathematical techniques to try in order to obtain solutions of the Einstein-Maxwell field equations since it has been demonstrated by Komathiraj and Maharaj [30], Thirukkanesh and Maharaj [31], Maharaj et al [32], Thirukkanesh and Ragel [33,34], Feroze and Siddiqui [35,36], Sunzu et al [37], Pant et al [38] and Malaver [39][40][41][42]. These investigations show that the system of Einstein-Maxwell equations plays an important role to describe ultracompacts objects.…”

Section: Introductionmentioning

confidence: 99%

Analytical Models for Quark Stars with Van Der Waals Modified Equation of State

Malaver¹,

2019

IJASS

Stellar models consisting of spherically symmetric distribution of charged matter locally anisotropic in strong gravitational fields have been widely considered in the frame of general relativity. These investigations require the generation of exact models through the resolution of the Einstein-Maxwell system of equations. The presence of charge produces values for redshifts, luminosity and mass for the stars different in relation to neutral matter. Some applications for dense charged matter we have them in the description of quark stars, spheres with linear or non-linear equation of state, hybrid stars and accreting process in compact objects where the matter acquires large amounts of electric charge. In this paper, we studied the behavior of relativistic compact objects with anisotropic matter distribution considering Van der Waals modified equation of state proposed in 2013 for Malaver and a gravitational potential Z(x) that depends on an adjustable parameter α in order to integrate analytically the field equations. They generalize the ideal gas law based on plausible reasons that real gases do not act ideally. New exact solutions of the Einstein-Maxwell system are generated and the physical variables as the energy density, radial pressure, mass function, anisotropy factor and the metric functions are written in terms of elementary and polynomial functions. We obtained expressions for radial pressure, density and mass of the stellar object physically acceptable with two different values of the adjustable parameter. The proposed models satisfy all physical features of a realistic star.

“…The existence of anisotropy within a star can be explained by the presence of a solid core, phase transitions, a type III super fluid, a pion condensation [26] or another physical phenomenon by the presence of an electrical field [27]. Many researchers and scientists have used a vast and great variety of mathematical techniques to try and test in order to obtain solutions of the Einstein-Maxwell field equations for anisotropic relativistic stars since it has been demonstrated by Komathiraj and Maharaj [28], Thirukkanesh and Maharaj [29], Maharaj et al [30], Thirukkanesh and Ragel [31,32], Feroze and Siddiqui [33,34], Sunzu et al [35], Pant et al [36] and Malaver [37][38][39][40]. These analyses indicate that the system of Einstein-Maxwell equations is very important in the description of ultracompacts objects.…”

Section: Introductionmentioning

confidence: 99%

Strange Stars Models in the Color-Flavor Locked State<strong> </strong>

Malaver¹,

2019

Preprint

In this paper, we found new classes of exact models to the Einstein-Maxwell system of equations which describe the internal structure of a compact star made of strange matter considering the equation of state proposed by Rocha, Bernardo, de Avellar and Horvath in 2019. It has been assumed that this matter is composed of equal number of up, down and strange quarks and a small amount of electrons required to reaching the charge neutrality. If this hypothesis is correct, the neutron stars could be strange stars or hybrid stars with a thin crust of nuclei where the temperatures and pressures are capable of converting hadronic matter into this new stable phase of quarks. We have chosen a particular form of gravitational potential Z(x) that depends on an adjustable parameter related to degree of anisotropy of the models and the new solutions can be written in terms of elementary and polynomial functions. The obtained models satisfy all physical features expected in a realistic star and the expressions for mass, density and stellar radius are comparable with the experimental results.