New relativistic charged models for compact stars
Malaver M and Iyer R
Published on: 2024-01-11
Abstract
In this paper, we found new classes of solutions to the Einstein-Maxwell field equations with matter anisotropic distribution incorporating a particular form of electric field intensity within the framework of general relativity. We use a metric potential or ansatz that depends on an adjustable parameter n in order to get the new solutions. We generated new models of compact stars with n=1 and n=2. Graphical analysis allows us to conclude that the new models satisfy all the physical characteristics for astrophysical objects and can be very useful in the study and description of compact structures. We obtained models consistent with the pulsars PSR J1311-3430 and PSR J0952–0607.
Keywords
Matter Anisotropic Distribution; General Relativity; Metric Potential; Compact Stars; Adjustable ParameterIntroduction
Research on compact objects and strange stars within the framework of the general theory of relativity is a central issue of great importance in theoretical astrophysics in the last decades [1,2]. The obtained models in general relativity have been used to describe fluid spheres with strong gravitational fields as is the case in strange stars and neutron stars. The physics of ultrahigh densities is not well understood and many of the strange stars studies have been performed within the framework of the MIT bag model where the matter equation of state has the following linear form . In this equation ρ is the energy density, P is the isotropic pressure and B is the bag constant. The first detailed models of strange stars based on a strange quark matter equation of state were modeled by Haensel et al. [3] who considered specific features of accretion on strange stars. Also Alcock et al. [4] analyzed strange stars with the normal crust and proposed scenarios for the formation of these compact objects.
Researches as Komathiraj and Maharaj [5], Thirukkanesh and Maharaj [6], Sharma et al. [7], Maharaj et al.[8], Thirukkanesh and Ragel [9,10], Feroze and Siddiqui [11,12], Sunzu et al.[13], Pant et al. [14] and Malaver [15-19], Sunzu and Danford [20], Komathiraj and Maharaj [21] have used numerous mathematical strategies to try to obtain exact solutions which indicates that the Einstein-Maxwell field equations is of great importance to describe compact objects.
The presence of an electric field within a fluid sphere has been a subject of great interest because it has allowed studying the effect of electromagnetic fields on astrophysical stellar objects. According Bhar and Murad [22] the existence of charge affects the values of redshifts, luminosities and mass for stars. Gupta and Maurya [23] have developed some stellar models with a well-defined electric field and Pant et al. [14] studied various solutions for charged matter with finite pressure.
In order to propose physical models of interest that behave well it is important to consider an adequate equation of state. Many researchers have developed exact analytical models of strange stars within the framework of linear equation of state based on MIT bag model together with a particular choice of metric potentials or mass function [24-34]. Mafa Takisa and Maharaj [35] obtained new exact solutions to the Einstein-Maxwell system of equations with a polytropic equation of state. Thirukkanesh and Ragel [36] have obtained particular models of anisotropic fluids with polytropic equation of state which are consistent with the reported experimental observations. Feroze and Siddiqui [11] and Malaver [15] consider a quadratic equation of state for the matter distribution and specify particular forms for the gravitational potential and electric field intensity. Bhar and Murad [22] obtained new relativistic stellar models with a particular type of metric function and a generalized Chaplygin equation of state. Tello-Ortiz et al. [37] also found an anisotropic fluid sphere solution of the Einstein-Maxwell field equations with a modified version of the Chaplygin equation. More recently Malaver and Iyer [38] generated new models of compact stars considering the new version of Chaplygin equation of state proposed for Errehymy and Daoud [39].
In recent decades, the theoretical research [40-50] in realistic stellar models show that the nuclear matter may be locally anisotropic in certain very high density ranges (ρ?1015 gcm-3), where the relativistic treatment of nuclear interactions in the stellar matter becomes important. From the pioneering work of Bowers and Liang [40] that generalized the equation of hydrostatic equilibrium for the case local anisotropy, there has been an extensive literature devoted to study the effect of local anisotropy on the bulk properties of spherically symmetric static general relativistic compact objects [51-54]. Therefore, it is always interesting to explore the consequences produced by the appearance of local anisotropy under variety of circumstances.
Presently there are efforts underway to understand the underlying quantum aspects with astrophysical charged Stellar models [55-60].
Shape of the metric potential depends on energy matter quantum wavefunction that can affect local anisotropy with interior criteria to be satisfied by the interior solution as to present a realistic stellar model, especially strange quark stars as well have been key in Quantum Astrophysical projects ongoing, including discontinuum physics [58-64]. There is also study of the quantum particle group theory with authors advancing that will help to classify general field-particle metrics that will match interior spacetime to the exterior spacetime linking also Standard Model and String Theories with Hubble and James Webb Telescope observations of the earlier genesis of galactical stars [59-61,65,66].
The principal motivation of this work is to develop some new analytical relativistic stellar models by obtaining of solutions of Einstein-Maxwell field equations with a linear equation of state with a particular shape of metric potential Z(x) dependent on an adjustable parameter n. The solutions obtained by satisfying applicable physical boundary conditions provide a mathematically simple family of electrically charged strange stars. The paper is structured as follows: the next section, Sect.2, are presented the interior solutions of Einstein-Maxwell field equations of anisotropic fluid. In Sect. 3, we present the elementary criteria to be satisfied by the interior solution as to present a realistic stellar model. In Sect. 4, physical acceptability conditions are discussed. The interior spacetime will be matched to the exterior spacetime described by the unique Reissner-Nordstrom metric, physically realistic fluid models will be constructed and analysis will be made on the obtained models in Sect. 5. Finally, Sect. 6 discusses and concludes the work.
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