Fluid approach of linear cosmological Nash–Greene perturbations

Abstract

In this paper, we obtain numerical solutions of the linear cosmological Nash-Greene perturbation equations in an embedded four dimensional space-time. We propose an effective fluid approach with the full anisotropic stresses to interpret the consequences of the extrinsic curvature on the cosmic dynamics. The effective Newtonian function G e f f is used to estimate the model parameters once it must obey Big Bang Nucleosynthesis and solar constraints. To obtain sufficiently accurate precision on the cosmic fluid parameter w , we use the Dynamic Nested Sampling algorithm with DYNESTY code to the obtainment of viable solutions of numerical evolutions of the matter growth rate, scalar fluid velocity, anisotropic quantities and on the analysis of effective sound speed. By means of a modified version of CLASS Einstein-Boltzmann solver, called EFCLASS , we obtain prospects on the resulting CMB TT angular spectra with the integrated Sachs-Wolfe effect, which is weakened on low- l scales as compared with the Λ CDM profile. Moreover, the obtained linear matter power spectrum P ( k ) profiles are compatible with Λ CDM standard results. • Dynamical approach for extrinsic curvature by means of Nash-Greene theorem. • Subhorizon linear perturbations in the embedding context. • A fluid approach for the extrinsic curvature with the full presence of anisotropic stresses. • The related ISW effect is suppressed as compared with the Λ CDM profiles.