A roadmap to cosmological parameter analysis with third-order shear statistics

I. Modelling and validation^⋆

Argelander-Institut für Astronomie, Auf dem Hügel 71, 53121 Bonn, Germany
e-mail: sven@astro.uni-bonn.de

Received: 27 August 2022
Accepted: 11 November 2022

Abstract

In this work, which is the first of a series to prepare a cosmological parameter analysis with third-order cosmic shear statistics, we model both the shear three-point correlation functions Γ⁽ⁱ⁾ and the third-order aperture statistics $\langle {\mathcal{M}}_{\text{ap}}^3\rangle$ from the B IHALOFIT bispectrum model and validate these statistics with a series of N-body simulations. We then investigate how to bin the shear three-point correlation functions to achieve an unbiased estimate for third-order aperture statistics in real data. Finally, we perform a cosmological parameter analysis on KiDS1000-like mock data with second- and third-order statistics. In the absence of systematic effects, we recover all cosmological parameters with very little bias. Furthermore, we find that a joint analysis almost doubles the constraining power on S₈ and increases the figure of merit in the Ω_m-σ₈ plane by a factor of 5.9 with respect to an analysis with only second-order shear statistics.