Cosmic shear cosmology beyond two-point statistics: a combined peak count and correlation function analysis of DES-Y1

Joachim Harnois-Déraps,Klaus Dolag,Benjamin Giblin,Qianli Xia,Hendrik Hildebrandt,Nicolas Martinet,Tiago Castro,Catherine Heymans

doi:10.1093/mnras/stab1623

Abstract

ABSTRACT We constrain cosmological parameters from a joint cosmic shear analysis of peak-counts and the two-point shear correlation functions, as measured from the Dark Energy Survey (DES-Y1). We find the structure growth parameter $S_8\equiv \sigma _8\sqrt{\Omega _{\rm m}/0.3} = 0.766^{+0.033}_{-0.038}$ which, at 4.8 per cent precision, provides one of the tightest constraints on S8 from the DES-Y1 weak lensing data. In our simulation-based method we determine the expected DES-Y1 peak-count signal for a range of cosmologies sampled in four w cold dark matter parameters (Ωm, σ8, h, w0). We also determine the joint covariance matrix with over 1000 realizations at our fiducial cosmology. With mock DES-Y1 data we calibrate the impact of photometric redshift and shear calibration uncertainty on the peak-count, marginalizing over these uncertainties in our cosmological analysis. Using dedicated training samples we show that our measurements are unaffected by mass resolution limits in the simulation, and that our constraints are robust against uncertainty in the effect of baryon feedback. Accurate modelling for the impact of intrinsic alignments on the tomographic peak-count remains a challenge, currently limiting our exploitation of cross-correlated peak counts between high and low redshift bins. We demonstrate that once calibrated, a fully tomographic joint peak-count and correlation functions analysis has the potential to reach a 3 per cent precision on S8 for DES-Y1. Our methodology can be adopted to model any statistic that is sensitive to the non-Gaussian information encoded in the shear field. In order to accelerate the development of these beyond-two-point cosmic shear studies, our simulations are made available to the community upon request.

Highlights

Over the last decade, weak gravitational lensing has emerged as one of the most promising techniques to investigate the properties of our Universe on cosmic scales
This paper aims to address this issue: we present a cosmological re-analysis of the Dark Energy Survey (DES)-Y1 cosmic shear data (Abbott et al 2018b), exploiting a novel simulation-based cosmology inference pipeline calibrated on state-of-the-art suites of N-body runs that are designed to analyse current weak lensing data beyond two-point statistics
We analyse the DES-Y1 cosmic shear data with a cosmology inference pipeline exclusively calibrated on suites of wCDM weak lensing numerical N-body simulations

Summary

Introduction

Weak gravitational lensing has emerged as one of the most promising techniques to investigate the properties of our Universe on cosmic scales. Following the success of the Canada-France-Hawaii Telescope Lensing Survey (Heymans et al 2012; Erben et al 2013), a series of dedicated Stage-III weak lensing experiments, namely the Kilo Degree Survey, the Dark Energy Survey and the Hyper Suprime Camera Survey, were launched and aimed at constraining properties of dark matter to within a few percent. These are well advanced or have recently completed their data acquisition, and the community is preparing for the generation of Stage IV experiments, notably the Rubin observatory, and the Euclid and Nancy Grace Roman space telescopes.

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