Tension between the power spectrum of density perturbations measured on large and small scales

Richard A. Battye; Tom Charnock; Adam Moss

doi:10.1103/PhysRevD.91.103508

paper

Tension between the power spectrum of density perturbations measured on large and small scales

arXiv:1409.2769 · doi:10.1103/PhysRevD.91.103508

Abstract

There is a tension between measurements of the amplitude of the power spectrum of density perturbations inferred using the Cosmic Microwave Background (CMB) and directly measured by Large-Scale Structure (LSS) on smaller scales. We show that this tension exists, and is robust, for a range of LSS indicators including clusters, lensing and redshift space distortions and using CMB data from either $P l an c k$ or WMAP+SPT/ACT. One obvious way to try to reconcile this is the inclusion of a massive neutrino which could be either active or sterile. Using $P l an c k$ and a combination of all the LSS data we find that (i) for an active neutrino $\sum m_{ν} = (0.357 \pm 0.099) eV$ and (ii) for a sterile neutrino $m_{sterile}^{eff} = (0.67 \pm 0.18) eV$ and $Δ N_{eff} = 0.32 \pm 0.20$ . This is, however, at the expense of a degraded fit to $P l an c k$ temperature data, and we quantify the residual tension at $2.5 σ$ and $1.6 σ$ for massive and sterile neutrinos respectively. We also consider alternative explanations including a lower redshift for reionization that would be in conflict with polarisation measurements made by WMAP and $a d$ - $h oc$ modifications to primordial power spectrum.

arXiv comment18 pages, 11 figures

Tension between the power spectrum of density perturbations measured on large and small scales

Abstract

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