Reconstructing the matter power spectrum with future cosmic shear surveys

TL;DR

This paper introduces a method to reconstruct the matter power spectrum from cosmic shear data, enabling more detailed cosmological insights and testing models of baryonic feedback and dark matter.

Contribution

It presents a novel approach to extract the full matter power spectrum from cosmic shear surveys, beyond the traditional $S_8$ parameter, including non-linear scales.

Findings

Cosmic shear surveys can probe the shape of the matter power spectrum on non-linear scales.

The method can distinguish between different baryonic feedback models.

It assesses the impact of systematics on power spectrum constraints.

Abstract

Analyses of cosmic shear typically condense weak lensing information over a range of scales to a single cosmological parameter, $S_8$. This paper presents a method to extract more information from Stage-IV cosmic shear measurements by directly reconstructing the matter power spectrum from linear to non-linear scales. We demonstrate that cosmic shear surveys will be sensitive to the shape of the matter power spectrum on non-linear scales. We show that it should be possible to distinguish between different models of baryonic feedback and we investigate the impact of intrinsic alignments and observational systematics on forecasted constraints. In addition to providing important information on galaxy formation, power spectrum reconstruction should provide a definitive answer to the question of whether weak lensing measurements of $S_8$ on linear scales are consistent with the $\textit{Planck}$ $\Lambda$CDM cosmology. In addition, power spectrum reconstruction may lead to new discoveries on the composition of the dark sector.