On quintessence star model and strange star
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Regular Article - Theoretical Physics
On quintessence star model and strange star Gabino Estevez-Delgado1,a , Joaquin Estevez-Delgado2,b 1
Facultad de Químico Farmacobiología de la Universidad Michoacana de San Nicolás de Hidalgo, Tzintzuntzan No. 173, Col. Matamoros, CP 58240 Morelia, Michoacán, Mexico 2 Facultad de Ciencias Físico Matemáticas de la Universidad Michoacana de San Nicolás de Hidalgo, Edificio B, Ciudad Universitaria, CP 58030 Morelia, Michoacán, Mexico
Received: 20 October 2019 / Accepted: 7 September 2020 © The Author(s) 2020
Abstract The astronomical observations on the accelerated expansion of the universe generate the possibility that the internal matter of the stars is not only formed by ordinary matter but also by matter with negative pressure. We discuss the existence of stars formed by the coexistence of two types of fluids, one associated to quintessence dark matter described by the radial and tangential pressures (Prq , Ptq ) and the density ρq characterized by a parameter −1 < w < − 13 and ordinary matter described by an anisotropic fluid with radial pressure of a strange star given by the MIT Bag model Pr = 13 (c2 ρ − 4Bg ) and tangential pressure Pt = 13 (c2 ρ − 4Bg ) − 23 (1 + w)c2 ρq , in which the effect is reflected of the quintessence dark matter over the ordinary matter. Via a theorem we show that the geometry that describes this interaction is equivalent to that of a perfect fluid with ordinary matter. Taking as geometry the one associated with a model for neutron stars, a physically acceptable and stable model is obtained. The application to the star Her X-1, as a candidate to a strange quark star, generates for us a value of the MIT Bag constant Bg = 97.0048 Mev/fm3 , which is found to be inside the expected interval.
1 Introduction The internal description of the stars, in the context of gravitation, has been approached from different perspectives from the scope of its composition, which determines the structure of the stress-energy tensor and the geometry, which defines the type of gravitational theory that will be considered. In the first of the aspects, the astronomic observations of the accelerated expansion of the universe [1] generate the possibility that the internal matter of the stars is not only formed by ordinary matter but also by matter with negative pressure, a e-mail:
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like quintessence [2]. Although its origin is cosmological, and that is where its presence is more transcendental, it is interesting to analyze what would happen at a stellar level, as minimal as its effects may be. There are diverse investigations around quintessence; for more than a decade it has been considered that quintessence is a good candidate to solve some problems in cosmolog. For example it has been argued that quintessence may explain the ’cosmic coincidence’ problem and may fit the observational data better than the cosmological constant [3], while its possible existence has a
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