On quintessence star model and strange star

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 $$(P_{rq},P_{tq})$$ ( P rq , P tq ) and the density $$\rho _{q}$$ ρ q characterized by a parameter $$-1<w<-\frac{1}{3}$$ - 1 < w < - 1 3 and ordinary matter described by an anisotropic fluid with radial pressure of a strange star given by the MIT Bag model $$P_r=\frac{1}{3}(c^2\rho -4B_g)$$ P r = 1 3 ( c 2 ρ - 4 B g ) and tangential pressure $$P_t=\frac{1}{3}(c^2\rho -4B_g)-\frac{3}{2}(1+w)c^2\rho _q$$ P t = 1 3 ( c 2 ρ - 4 B g ) - 3 2 ( 1 + w ) c 2 ρ q , 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 $$B_g = 97.0048\,\mathrm{Mev}/\mathrm{fm}^3$$ B g = 97.0048 Mev / fm 3 , which is found to be inside the expected interval.

Determination of the charge for strange stars

“…It is also applicable in alternative gravitational theory models [80,81]. This same geometry allows for the description of models that are differentiated for the type of sources of matter in situations with or without equation of state [74,[76][77][78][79][80][81].…”

“…It is also applicable in alternative gravitational theory models [80,81]. This same geometry allows for the description of models that are differentiated for the type of sources of matter in situations with or without equation of state [74,[76][77][78][79][80][81]. The different models proposed were applied to describe the interior of many stellar objects for which their observational data is known and also it has been shown that the geometry is regular and absent of event horizon, motivated by this, in this report the focus will be centered in the construction of a model, the description of it's behaviour and it's application to determining the possible values of the charge considering some values of the Bag constant inside of the admissible interval of it.…”

“…In these models part of the difficulty lies in being able to obtain that the union between two or more regions, for example in the case of two regions, one an inner layer we will call core and an outer layer we will call envelope both with distinct pressures, the conditions of continuity are satisfied between the first fundamental form and the second fundamental form, described by the conditions of Israel [28]. As such, the description of their interior is not a simple task and with the intent of obtaining a better description for stars with a greater compactness, taking elements that help us understand these, there have been proposals for state equations that even consider the existence of quintessence inside them [29][30][31][32][33] showing that this model is consistent with the required properties of behaviour and with the observational data of mass and radius. On the other hand, the possibility that quark stars exist arises due to the fact that in the interior of the neutron stars there may be a phase transition from neutrons to hyperons and strange quark matter [34].…”

A charged star with geometric Karmarkar condition

“…Objects with a greater compactness than in the case of a perfect fluid, corresponding to the Buchdahl limit [1] u ≡ GM/c 2 R < 4/9, can occur when we have a difference between the radial pressure P r and the tangential pressure P t , known as anisotropy Δ = P t − P r [2], in the presence of electric charge [3][4][5] or when we have both situations. The anisotropy in relation to compact objects has been addressed in the analysis of stars with ordinary matter for an incompressible fluid [6] and with non-constant density [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21], in the analysis of bosonic stars [22], in the context of Brans-Dicke gravity [23], in alternative gravitation theories like the f (T) [24], in the consideration of stars with quintessence type matter [25][26][27][28][29] and also in the analysis of hypothetical objects such as gravastars [30]. In the charged case we have models that consider a perfect charged fluid [31][32][33][34][35][36][37] as well as in the case of objects with charged anisotropic fluid [38][39][40][41][42]…”

Charged strange star coupled to anisotropic dark energy in Tolman–Kuchowicz spacetime

“…Ray et al studied the effect of electric charge in compact stars assuming that the charge distribution is proportional to the mass density and the relativistic hydrostatic equilibrium equation, i.e., the Tolman-Oppenheimer-Volkoff equation, gets modified due to the inclusion of electric charge [27]. The dynamics of cold star models, compact stars, strange stars, and other stellar configurations with the hybrid coupling of strange matter have been the subject of continuous research during the last decade [28][29][30][31][32][33][34][35][36][37][38][39][40][41].…”