Constraints on $$\sigma _8$$ and degeneracies from linear Nash-Greene perturbations in subhorizon scale

Abstract

Using a joint statistical analysis, we test a four-dimensional FLRW model embedded in a five-dimensional bulk based on the Nash-Greene embedding theorem. Performing a Markov Chain Monte Carlo (MCMC) modelling, we combine observational data sets as those of the recent growth data, the best-fit Planck2018/$$\varLambda $$ Λ CDM parameters on the Cosmic Microwave Background (CMB), the Baryon Acoustic Oscillations (BAO) measurements, the Pantheon Supernovae type Ia and the Hubble parameter data. From linear Nash-Greene fluctuations of the metric, we show the related perturbed equations in longitudinal Newtonian gauge to obtain the evolution of growth matter. A mild alleviation may be obtained from the degeneracies on the model parameter analyzing the $$\sigma $$ σ tension between the growth amplitude factor and the matter content in the plane $$(\sigma _8$$ ( σ 8 -$$\varOmega _m)$$ Ω m ) on the observations from CMB and Large Scale Structure (LSS) probes. The Akaike Information Criterion (AIC) is also applied and we find a relative statistical consistence of the present model with both $$\varLambda $$ Λ CDM and wCDM models lower than 1$$\%$$ % of percentage difference at early times on the evolution of the Hubble function H(z). We also apply the Om(z) diagnosis to distinguish the present model from $$\varLambda $$ Λ CDM and wCDM models.

Can varying the gravitational constant alleviate the tensions?

“…[42]. This was also found by similar attempts to fix the discrepancy with some of the models we mentioned earlier [19,20,[43][44][45]. Other approaches were explored meant to have a transition of G at same particular redshift, see [46][47][48][49].…”

Can varying the gravitational constant alleviate the tensions ?

“…[41]. This was also found by similar attempts to fix the discrepancy with some of the models we mentioned earlier [19,20,42,43]. Other approaches were explored meant to have a transition of G at same particular redshift, see [44][45][46].…”