Testing dark energy models in the light of σ8 tension

It has been pointed out that there exists a tension in σ8−Ωm measurement between CMB and LSS observation. In this paper we show that σ8−Ωm observations can be used to test the dark energy theories. We study two models, (1) Hu–Sawicki (HS) Model of f(R) gravity and (2) Chavallier–Polarski–Linder (CPL) parametrization of dynamical dark energy (DDE), both of which satisfy the constraints from supernovae. We compute σ8 consistent with the parameters of these models. We find that the well known tension in σ8 between Planck CMB and large scale structure (LSS) observations is (1) exacerbated in the HS model and (2) somewhat alleviated in the DDE model. We illustrate the importance of the σ8 measurements for testing modified gravity models. Modified gravity models change the matter power spectrum at cluster scale which also depends upon the neutrino mass. We present the bound on neutrino mass in the HS and DDE model.by Gaetano Lambiase, Subhendra Mohanty, Ashish Narang and Priyank Parashar