Exact EGB models for spherical static perfect fluids
Abstract
We obtain a new exact solution to the field equations for a 5dimensional spherically symmetric static distribution in the EinsteinGaussBonnet modified theory of gravity. By using a transformation, the study is reduced to the analysis of a single second order nonlinear differential equation. In general the condition of pressure isotropy produces a first order differential equation which is an Abel equation of the second kind. An exact solution is found. The solution is examined for physical admissibility. In particular a set of constants is found which ensures that a pressurefree hypersurface exists which defines the boundary of the distribution. Additionally the isotropic pressure and the energy density are shown to be positive within the radius of the sphere. The adiabatic soundspeed criterion is also satisfied within the fluid ensuring a subluminal sound speed. Furthermore, the weak, strong and dominant conditions hold throughout the distribution. On setting the GaussBonnet coupling to zero, an exact solution for 5dimensional perfect fluids in the standard Einstein theory is obtained. Plots of the dynamical quantities for the GaussBonnet and the Einstein case reveal that the pressure is unaffected, while the energy density increases under the influence of the GaussBonnet term.
 Publication:

European Physical Journal C
 Pub Date:
 June 2015
 DOI:
 10.1140/epjc/s1005201535048
 arXiv:
 arXiv:1502.02219
 Bibcode:
 2015EPJC...75..277H
 Keywords:

 General Relativity and Quantum Cosmology
 EPrint:
 18 pages, Submitted for publication