New models for perfect fluids in EGB gravity

Chilambwe, Brian; Hansraj, Sudan; Maharaj, S. D.

doi:10.1142/s0218271815500510

Cited by 49 publications

(32 citation statements)

References 24 publications

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“…Recently exact interior metrics were reported [1][2][3] for spherically symmetric perfect fluid distributions in the EinsteinGauss-Bonnet (EGB) gravity theory. The exterior metric was derived by Boulware and Deser [4] for neutral spheres and by Wiltshire [5] for the charged counterpart a few decades ago.…”

Section: Introductionmentioning

confidence: 99%

“…For example, the Kerr-Schild ansatz known to linearize the Einstein tensor was attempted in EGB theory [12] and it was found that the solution of the trace of the EGB equations did not solve all the field equations. Success in solving the EGB equations was achieved through a coordinate transformation [1][2][3]. This transformation was customarily used in the standard Einstein theory to convert the equation of pressure isotropy to a linear differential equation in any of the two gravitational potentials.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Introductionmentioning

confidence: 99%

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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“…These were the EGB analogues of those found in [8,9]. New solutions to the EGB field equations for a static spherically symmetric interior of a fluid were found in [23][24][25], and the generalised Israel junction conditions on a membrane were derived in detail by Davis [26]. These results for type I or type II (or combinations of the two) fluids have proven fruitful in stellar modeling, both in general relativity and EGB gravity.…”

Section: Introductionmentioning

confidence: 65%

“…then gives the diffusion equation (24). Expressing the EGB field equations (19) and (20) as M r = 1 3 rρ s and…”

Section: Derivation Of the Diffusion Equationmentioning

confidence: 99%

Generalised radiating fields in Einstein–Gauss–Bonnet gravity

Brassel

Maharaj

2020

Eur. Phys. J. C

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A five-dimensional spherically symmetric generalised radiating field is studied in Einstein–Gauss–Bonnet gravity. We assume the matter distribution is an extended Vaidya-like source and the resulting Einstein–Gauss–Bonnet field equations are solved for the matter variables and mass function. The evolution of the mass, energy density and pressure are then studied within the spacetime manifold. The effects of the higher order curvature corrections of Einstein–Gauss–Bonnet gravity are prevalent in the analysis of the mass function when compared to general relativity. The effects of diffusive transport are then considered and we derive the specific equation for which diffusive behaviour is possible. Gravitational collapse is then considered and we show that collapse ends with a weak and conical singularity for the generalised source, which is not the case in Einstein gravity.

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“…Recently we discovered exact solutions that could model the interiors of relativistic perfect fluid stars in the EGB framework [5][6][7] . These were shown to harmonise with the standard conditions for physical admissability in Einstein gravity such as positive-definiteness of dynamical variables, conformity to the causality criterion, the existence of a pressure free boundary hypersurface and conformity to the energy conditions.…”

Section: And Refmentioning

confidence: 99%

Interior metrics for higher dimensional spherically symmetric fluids in Einstein-Maxwell-Gauss-Bonnet theory

Hansraj¹

2017

The Fourteenth Marcel Grossmann Meeting

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Recently exact solutions for the interiors of neutral relativistic spherically symmetric stars were obtained in the Einstein-Gauss-Bonnet gravity theory 5-7 . We investigate the problem of finding spacetimes for perfect fluids in electric fields. In this regards, the Einstein-Gauss-Bonnet field equations are supplemented by the Maxwell's equations. It turns out that the problem amounts to solving a system of four partial differential equations in six unknowns. Two of the geometrical or dynamical variables may be chosen a priori and the remaining four may be determined by integration. We are able to find exact models by utilising metric ansatze equivalent to the Schwarzschild interior metric as well as the Finch Skea metric for the standard Einstein gravity. Additional new solutions are reported for different choices of the electric field and gravitational potential. A study of such solutions is proceeding. In particular we investigate the role of the charge on the mass-radius relationship and consequently the equation of state if it can be explicitly found. The usual Einstein junction conditions are extrapolated to the EMGB case and we require the existence of a pressure free hypersurface to define the boundary of the star. The energy conditions are also examined as is the causality criterion.

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New models for perfect fluids in EGB gravity

Cited by 49 publications

References 24 publications

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

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

Generalised radiating fields in Einstein–Gauss–Bonnet gravity

Interior metrics for higher dimensional spherically symmetric fluids in Einstein-Maxwell-Gauss-Bonnet theory

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