In this work we have extended the Maurya-Gupta isotropic fluid solution to Einstein field equations to an aniso-tropic domain. To do so, we have employed the gravitational decoupling via the minimal ...geometric deformation approach. The present model is representing the strange star candidate LMC X-4. A mathematical, physical and graphical analysis, shown that the obtained model fulfills all the criteria to be an admissible solution of the Einstein field equations. Specifically, we have analyzed the regularity of the metric potentials and the effective density, radial and tangential pressures within the object, causality condition, energy conditions, equilibrium via Tolman–Oppenheimer–Volkoff equation and the stability of the model by means of the adiabatic index and the square of subliminal sound speeds.
In the present article, we have obtained a new solution for the charged compact star model through the gravitational decoupling (GD) by using a complete geometric deformation (CGD) approach (Ovalle, ...Phys Lett B 788:213, 2019). In this approach, the initial decoupled system is separated into two subsystems namely Einstein–Maxwell’s system and quasi-Einstein system. We solve Einstein–Maxwell’s system by taking well known Tolman–Kuchowicz spacetime geometry in the context of the perfect fluid matter distribution. On the other hand, the second system introduce the anisotropy inside the matter distribution which is solved by taking an EOS in
θ
components. The boundary conditions have been derived to determine the constants parameter. To support the mathematical and physical analysis of the present GD solution, we have plotted all the graphs for the compact objects PSR J1614-2230, 4U1608-52 and Cen X-3 corresponding to the constant
α
=
0.001
, 0.0012 and 0.0014, respectively. Moreover, we also studied the equilibrium and stability of the solution. The present study shows that the GD technique is a very significant tool to generalize the solution in a more complex form or one matter distribution to another matter distribution.
In this article, we have investigated a new completely deformed embedding class one solution for the compact star in the framework of charged anisotropic matter distribution. For determining of this ...new solution, we deformed both gravitational potentials as
ν
↦
ξ
+
α
h
(
r
)
and
e
-
λ
↦
e
-
μ
+
α
f
(
r
)
by using Ovalle (Phys Lett B 788:213, 2019) approach. The gravitational deformation divides the original coupled system into two individual systems which are called the Einstein’s system and Maxwell-system (known as quasi-Einstein system), respectively. The Einstein’s system is solved by using embedding class one condition in the context of anisotropic matter distribution while the solution of Maxwell-system is determined by solving of corresponding conservation equation via assuming a well-defined ansatz for deformation function
h
(
r
). In this way, we obtain the expression for the electric field and another deformation function
f
(
r
). Moreover, we also discussed the physical validity of the solution for the coupled system by performing several physical tests. This investigation shows that the gravitational decoupling approach is a powerful methodology to generate a well-behaved solution for the compact object.
In the present paper, we discuss the role of gravitational decoupling to isotropize the anisotropic solution of Einstein’s field equations in the context of the complete geometric deformation (CGD) ...approach and its influence on the complexity factor introduced by Herrera (Phys Rev D 97:044010, 2018) in the static self-gravitating system. Moreover, we proposed a simple and effective technique as well to generate new solutions for self-gravitating objects via CGD approach by using two systems with the same complexity factor and vanishing complexity factor proposed by Casadio et al. (Eur Phys J C 79:826, 2019). The effect of decoupling constant and the compactness on the complexity factor have also been analyzed for the obtained solutions.
The present work is focused on the investigation of the existence of compact structures describing anisotropic matter distributions within the framework of modified gravity theories, specifically ...f(R,T) gravity theory. Additionally, we have taken f(R,T) as a linear function of the Ricci scalar R and the trace of the energy-momentum tensor T as f(R,T)=R+2χT, where χ is a dimensionless coupling parameter, and the Lagrangian matter Lm=−13(2pt+pr), to describe the complete set of field equations for the anisotropic matter distribution. We follow the embedding class I procedure using the Eisland condition to obtain a full space-time description inside the stellar configuration. Once the space-time geometry is specified, we determine the complete solution of modified Einstein equations by using the MIT bag model equation of state pr=13(ρ−4B) that describes the strange quark matter (SQM) distribution inside the stellar system, where B denotes a bag constant. The physical validity of our anisotropic solution is confirmed by executing several physical tests. It is worth mentioning that with the help of the observed mass values for the various strange star candidates, we have predicted the exact radii by taking different values for χ and B. These predicted radii show a monotonic decreasing nature as the parameter χ is moved from −0.8 to 0.8 progressively. In this case, our anisotropic stellar system becomes more massive and transforms into more dense compact stars. We also perform a detailed graphical analysis of the compact star. As a result, for χ<0, the current modified f(R,T) gravity seems promising to explain the observed massive compact astrophysical objects, similar to magnetars, massive pulsars, and Chandrasekhar super white dwarfs, which are not justified in the framework of general relativity. Finally, we note that when χ=0, general relativity results for anisotropic matter distributions are recovered.
We obtain a new anisotropic solution for spherically symmetric spacetimes by analyzing the Karmarkar embedding condition. For this purpose we construct a suitable form of one of the gravitational ...potentials to obtain a closed form solution. This form of the remaining gravitational potential allows us to solve the embedding equation and integrate the field equations. The resulting new anisotropic solution is well behaved, which can be utilized to construct realistic static fluid spheres. Also we estimated the masses and radii of fluid spheres for LMC X-4, EXO 1785-248, PSR J1903+327 and 4U 1820-30 by using observational data set values. The masses and radii obtained show that our anisotropic solution can represent fluid spheres to a very good degree of accuracy. The physical validity of the solution depends on the parameter values of
a
,
b
and
c
. The solution is well behaved for the wide range of parameters values
0.00393
≤
a
≤
0.0055
,
0.0002
≤
b
≤
0.0025
and
0.0107
≤
c
≤
0.0155
. The range of corresponding physical parameters for the different compact stars are
0.3266
≤
v
r
0
≤
0.3708
,
0.1583
≤
v
t
0
≤
0.2558
,
0.3256
≤
z
s
≤
0.4450
and
4.3587
≤
Γ
0
≤
5.6462
.
We investigate a compact spherically symmetric relativistic body with anisotropic particle pressure profiles. The distribution possesses characteristics relevant to modeling compact stars within the ...framework of general relativity. For this purpose, we consider a spatial metric potential of Korkina and Orlyanskii Ukr. Phys. J. 36, 885 (1991) type in order to solve the Einstein field equations. An additional prescription we make is that the pressure anisotropy parameter takes the functional form proposed by Lake Phys. Rev. D 67, 104015 (2003). Specifying these two geometric quantities allows for further analysis to be carried out in determining unknown constants and obtaining a limit of the mass-radius diagram, which adequately describes compact strange star candidates like Her X-1 and SMC X-1. Using the anisotropic Tolman-Oppenheimer-Volkoff equations, we explore the hydrostatic equilibrium and the stability of such compact objects. Then, we investigate other physical features of this model, such as the energy conditions, speeds of sound, and compactness of the star, in detail and show that our results satisfy all the required elementary conditions for a physically acceptable stellar model. The results obtained are useful in analyzing the stability of other anisotropic compact objects like white dwarfs, neutron stars, and gravastars.
Class I approach as MGD generator Tello-Ortiz, Francisco; Maurya, S. K.; Gomez-Leyton, Y.
The European physical journal. C, Particles and fields,
04/2020, Letnik:
80, Številka:
4
Journal Article
Recenzirano
Odprti dostop
In this work we build a relativistic anisotropic admissible compact structures. To do so we combine the class I approach with gravitational decoupling in order to generate the deformation function
f
...(
r
). As an example we have re-anisotropized two anisotropic matter distributions previously obtained by the class I procedure. To produce all the graphical study supporting this analysis, we have considered the data corresponding to the compact object 4U 1538-52, SMC X-1 and LMC X-4 for model 1 and Cen X-3 for model 2. In considering the last one, we have taken the constant parameter
α
to be
{
-
0.3
;
0.1
;
0.3
}
. It is found that the resulting models satisfy all the general requirement in order to represent or describe realistic compact structures such as neutron or quark stars.
In this article, we have presented a static anisotropic solution of stellar compact objects for self-gravitating system by using minimal geometric deformation techniques in the framework of embedding ...class one space-time. For solving of this coupling system, we deform this system into two separate system through the geometric deformation of radial components for the source function
λ
(
r
)
by mapping:
e
-
λ
(
r
)
→
e
-
λ
~
(
r
)
+
β
g
(
r
)
, where
g
(
r
) is deformation function. The first system corresponds to Einstein’s system which is solved by taking a particular generalized form for source function
λ
~
(
r
)
while another system is solved by choosing well-behaved deformation function
g
(
r
). To test the physical viability of this solution, we find complete thermodynamical observable as pressure, density, velocity, and equilibrium condition via. TOV equation etc. In addition to the above, we have also obtained the moment of inertia (
I
), Kepler frequency (
v
), compression modulus (
K
e
) and stability for this coupling system. The
M
–
R
curve has been presented for obtaining the maximum mass and corresponding radius of the compact objects.
Utilizing an ansatz developed by Maurya et al. we present a class of exact solutions of the Einstein–Maxwell field equations describing a spherically symmetric compact object. A detailed physical ...analysis of these solutions in terms of stability, compactness and regularity indicates that these solutions may be used to model strange star candidates. In particular, we model the strange star candidate Her X-1 and show that our solution conforms to observational data to an excellent degree of accuracy. An interesting and novel phenomenon which arises in this model is the fact that the relative difference between the electromagnetic force and the force due to the pressure anisotropy changing sign within the stellar interior. This may be an additional mechanism required for stability against cracking of the stellar object.
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