Compact objects in pure Lovelock theory

Dadhich, Naresh; Hansraj, Sudan; Chilambwe, Brian

doi:10.1142/s0218271817500560

Cited by 40 publications

(29 citation statements)

References 42 publications

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“…When this form is substituted into the isotropy equation (18) the resulting differential equation proves intractable to solve. Note that this situation does not arise in the standard Einstein gravity since on setting χ = 0 for the Einstein case, (16) can be solved explicitly for λ in terms of r. This has been amply demonstrated by Dadhich et al [29,32] for the Einstein case and its generalization pure Lovelock theory.…”

Section: Relaxing the Equation Of Statementioning

confidence: 99%

Spherically symmetric isothermal fluids in f(R, T) gravity

Hansraj

2018

Eur. Phys. J. C

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We analyze the isothermal property in static fluid spheres within the framework of the modified f (R, T ) theory of gravitation. The equation of pressure isotropy of the standard Einstein theory is preserved however, the energy density and pressure are expressed in terms of both gravitational potentials. Invoking the isothermal prescription requires that the isotropy condition assumes the role of a consistency condition and an exact model generalizing that of general relativity is found.Moreover it is found that the Einstein model is unstable and acausal while the f (R, T ) counterpart is well behaved on account of the freedom available through an additional coupling constant.The case of a constant spatial gravitational potential is considered and the complete model is determined. This model is markedly different from its Einstein counterpart which is known to be isothermal. Dropping the restriction on the density and imposing a linear barotropic equation of state generates an exact solution and consequently a stellar distribution as the vanishing of the pressure is possible and a boundary hypersurface exists. Finally we comment on the case of relaxing the equation of state but demanding an inverse square fall-off of the density -this case proves intractable.

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Section: Relaxing the Equation Of Statementioning

confidence: 99%

Spherically symmetric isothermal fluids in f(R, T) gravity

Hansraj

2018

Eur. Phys. J. C

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“…Pandya et al [27] found models with geometry consistent with observed radii and masses for dense stars. The Finch-Skea geometry has also been studied for higher dimensional gravitational geometries [28][29][30][31] and trace-free gravity [32].…”

Section: Finch-skea Geometrymentioning

confidence: 99%

Static conformal models for anisotropic charged fluids

2019

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We investigate the role played by conformal symmetries in the study of exact solutions in static spherically symmetric spacetimes. We consider the gravitational field associated with anisotropic charged fluids. The existence of a conformal symmetry provides us with a functional relation between the metric functions. This relationship yields a general solution to the Einstein-Maxwell equations. Various conformally symmetric models for fluids that are charged or anisotropic or both are shown to be special cases of the general exact solution generated in this paper. In particular we generate a conformally flat Finch-Skea type model for an isotropic charged fluid.

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“…These include satisfying the energy conditions, the existence of a pressure free hypersurface determining the boundary of the sphere as well as the condition of causality. A similar programme proved successful in constructing compact pure Lovelock stars [13].…”

Section: Introductionmentioning

confidence: 99%

Generalized spheroidal spacetimes in 5-D Einstein–Maxwell–Gauss–Bonnet gravity

Hansraj

2017

Eur. Phys. J. C

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The field equations for static EGBM gravity are obtained and transformed to an equivalent form through a coordinate redefinition. A form for one of the metric potentials that generalizes the spheroidal ansatz of Vaidya-Tikekar superdense stars and additionally prescribing the electric field intensity yields viable solutions. Some special cases of the general solution are considered and analogous classes in the Einstein framework are studied. In particular the FinchSkea ansatz is examined in detail and found to satisfy the elementary physical requirements. These include positivity of pressure and density, the existence of a pressure free hypersurface marking the boundary, continuity with the exterior metric, a subluminal sound speed as well as the energy conditions. Moreover, the solution possesses no coordinate singularities. It is found that the impact of the Gauss-Bonnet term is to correct undesirable features in the pressure profile and sound speed index when compared to the equivalent Einstein gravity model. Furthermore graphical analyses suggest that higher densities are achievable for the same radial values when compared to the 5-dimensional Einstein case. The case of a constant gravitational potential, isothermal distribution as well as an incompressible fluid are studied. All exact solutions derived exhibit an equation of state explicitly.

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Compact objects in pure Lovelock theory

Cited by 40 publications

References 42 publications

Spherically symmetric isothermal fluids in f(R, T) gravity

Spherically symmetric isothermal fluids in f(R, T) gravity

Static conformal models for anisotropic charged fluids

Generalized spheroidal spacetimes in 5-D Einstein–Maxwell–Gauss–Bonnet gravity

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