Lensing without mixing: Probing Baryonic Acoustic Oscillations and other scale-dependent features in cosmic shear surveys

TL;DR

This paper shows how a specific de-projection technique can be used to extract baryonic acoustic oscillations and other scale-dependent features from cosmic shear surveys, despite lensing's smoothing effect.

Contribution

It introduces a novel method leveraging the BNT transform and re-weighting to recover scale-dependent features in weak lensing data that are typically washed out.

Findings

BAO signals can be extracted using the BNT transform.

Lensing does not erase scale-dependent features when using the proposed method.

The approach enhances the detection of non-Gaussian properties in lensing data.

Abstract

Weak-gravitational lensing tends to wash out scale and time-dependent features of the clustering of matter, such as the Baryonic Acoustic Oscillations (BAO) which appear in the form of wiggles in the matter power spectrum but that disappear in the analogous lensing $C_\ell$. This is a direct consequence of lensing being a projected effect. In this paper, we demonstrate how the noise complexity -- often deemed "erasing the signal" -- induced by a particular de-projection technique, the Bernardeau-Nishimichi-Taruya (BNT) transform arXiv:1312.0430, can be used to extract the BAO signal and non-gaussian aperture-mass-like properties at chosen physical scales. We take into account parts of the data vectors that should effectively be without cosmological signature and also introduce an additional re-weighting designed to specifically highlight clustering features -- both at the probe (summary statistics) or map (amplitude of the field) level. We thus demonstrate why weak-gravitational lensing by the large-scale structure of the Universe, though only in a tomographic setting, does not erase scale and time-dependent features of the dynamics of matter, while providing a tool to effectively extract them from actual galaxy-shapes measurements.