Ray-tracing log-normal simulation for weak gravitational lensing: application to the cross-correlation with galaxies

TL;DR

This paper introduces a new simulation algorithm that generates realistic weak lensing and galaxy distribution maps, enabling precise cross-correlation forecasts for upcoming surveys like HSC and PFS.

Contribution

The authors develop a self-consistent log-normal simulation method for weak lensing and galaxy fields, improving the accuracy of cross-correlation predictions.

Findings

High-precision agreement with theoretical cross-power spectra

Forecasted detection SNRs of 20 for HSC and 5 for PFS

Demonstrated the simulation's effectiveness for survey planning

Abstract

We present an algorithm to self-consistently generate mock weak gravitational lensing convergence fields and galaxy distributions in redshift space. We generate three-dimensional cosmic density fields that follow a log-normal distribution, and ray-trace them to produce convergence maps. As we generate the galaxy distribution from the same density fields in a manner consistent with ray-tracing, the galaxy-convergence cross-power spectrum measured from the mock agrees with the theoretical expectation with high precision. We use this simulation to forecast the quality of galaxy-shear cross-correlation measurements from the Subaru Hyper Suprime-Cam (HSC) and Prime Focus Spectrograph (PFS) surveys. We find that the nominal HSC and PFS surveys would detect the cross power spectra with signal-to-noise ratios of 20 and 5 at the lowest ($z = 0.7$) and highest ($z = 2.2$) redshift bins, respectively.