A perfect fluid model for neutron stars

Abstract

In this paper, we present a physically acceptable internal solution with a perfect fluid, which needs the pressure and density as regular, positive and monotonic decreasing functions and with a speed of sound positive and lower than the speed of light. This solution depends on a parameter [Formula: see text], and it is physically acceptable if [Formula: see text], the compactness has a maximum value for the maximum value of [Formula: see text] and it corresponds to [Formula: see text], thus the model can be applicable to the description of compact stars. In a complementary way, we present the description of a star with mass equal to the sun mass and radius of [Formula: see text] Km associated to the neutron star Her X-1, obtaining a central density [Formula: see text] which is characteristic of the neutron stars.

A charged perfect fluid model with high compactness

“…Nowadays it is known that this form guarantees the regularity of the geometry in the vicinity of the center, since for this it is only required that [30] So other functions can be proposed with these properties. The proposed form for the function y(r) and other similar functions have allowed to show the relevance of the existence of anisotropic pressures to be able to have physically acceptable models [31] besides that they have been applied for the description of physically acceptable stellar models [30,32,33], some of which are characterized because the speed of sound is a decreasing monotonic function as a function of the radial coordinate [34]. The construction of interior solutions is useful to have a better clarity of the inner behavior of the stars [12], some solutions with perfect fluid sources without charge [29,35,36] these became generalized to charged case [37][38][39] to represent compact stars.…”

An interior solution with perfect fluid

“…In some works presented in the last century, there were some solutions found for the equation systems (3)-(5), considering the form of the gravitational potential 9 g tt = (1 + ar 2 ) n and recently it has been shown that different choices allow for the description of compact objects. [10][11][12] In this work, we assume the form of that gravitational potential as…”

“…The conditions required for an static and spherically symmetrical solution with perfect fluid to be physically acceptable conjugate aspects related with the geometry and the source of matter are enunciated in a summary manner as follows. 9,10 (1) The solution must be regular, i.e. the geometry and the physical quantities inside the star have to be non-singular.…”

“…Some solutions that are physically acceptable have been employed to describe stars. 8,[10][11][12][13][14] Recently, with the development of other gravitation theories, the themes that could only be approached with the general theory of relativity have been extended to other theories, the analysis of internal solutions has not been the exception. In the F (R) theory, the existence of neutron stars and quark stars has been studied, 15,16 as well as the stability.…”

Anisotropic neutron stars by gravitational decoupling

“…Recently, a perfect fluid interior solution has been reported in Ref. [70] and has been used to model the neutron star PSR J0348+0432. It is our main goal here extend this solution by MGD to model not only the compact object PSR J0348+0432 but the Binary Pulsar SAX J1808.4-3658 and X-ray Binaries Her X-1 and Cen X-3 ones.…”