An anisotropic charged fluids with Chaplygin equation of state

Abstract

A stellar model with an electrically charged anisotropic fluid as a source of matter is presented. The radial pressure is described by a Chaplygin state equation, [Formula: see text], while the anisotropy [Formula: see text] is annulled in the center of the star [Formula: see text] is regular and [Formula: see text], the electric field, is also annulled in the center. The density pressures and the tangential speed of sound are regular, while the radial speed of sound is monotonically increasing. The model is physically acceptable and meets the stability criteria of Harrison–Zeldovich–Novikov and in respect of the cracking concept the solution is unstable in the region of the center and potentially stable near the surface. A graphic description is presented for the case of an object with a compactness rate [Formula: see text], mass [Formula: see text] and radius [Formula: see text] km that matches the star Vela X-1. Also, the interval of the central density [Formula: see text], which is consistent with the expected magnitudes for this type of stars, which shows that the behavior is accurate for describing compact objects.

Determination of the charge for strange stars

“…guarantees the absence of event horizons. In addition of this the functions (9) that describe the geometry were initially proposed to model anisotropic chargeless and charged perfect fluid objects [74], afterwards they were employed for the case of a charged anisotropic fluid with a state equation type Chaplygin [76] and with quintessence sources of matter [77], as well as for a linear equation of state [78] and non linear equation of state [79].…”

“…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.…”

A charged star with geometric Karmarkar condition

“…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][43][44][45][46]. From a theoretical point of view, the anisotropy may occur for different motives: when the density of the matter is superior to 10 15 g/cm 3 Δ ≠ 0 as a result that at these orders the interactions are relativistic [47]; phase transitions of the matter, when changing to a su...…”

Relativistic charged stellar modeling with a perfect fluid sphere

“…In the first works, this reduction of a charged model to a chargeless model was an imposed requirement in the construction of charged interior solutions, however, recent investigations focus more on proposals of solutions that satisfy the requirements that the density and pressure are monotonically decreasing functions and that it satisfies the stability criteria [61][62][63]. Or well in charged models with anisotropic pressures, that is to say, different radial and tangential pressures, for which there is a state equation between the radial pressure and the density P r = P r (ρ) the type of state equation that has been analyzed were lineal [64,65], quadratic [14], Van der Waals [66], Polytropic [67] or Chaplygin type [68]. One alternative which generates a repulsive force effect, without the presence of electric charge, occurs when there is anisotropy in the pressure Δ = P t − P r > 0, if Δ < 0 the anisotropy will generate an attraction [69,70].…”