Super-cluster simulations: impact of baryons on the matter power spectrum and weak lensing forecasts for Super-CLASS

TL;DR

This study uses hydrodynamic and dark matter simulations to assess how baryons and super-cluster regions influence the matter power spectrum and weak lensing signals, with implications for the Super-CLASS survey's ability to detect cosmic shear.

Contribution

It provides new insights into the combined effects of baryonic physics and super-cluster selection on matter and shear power spectra, relevant for cosmological surveys.

Findings

Super-cluster regions have at least twice the matter power spectrum power of random regions.

Baryonic effects are weaker than selection effects on most scales.

Super-CLASS could detect cosmic shear with a significance of approximately 2.7 sigma.

Abstract

We use a combination of full hydrodynamic and dark matter only simulations to investigate the effect that baryonic physics and selecting super-cluster regions have on the matter power spectrum, by re-simulating a sample of super-cluster sub-volumes. On large scales we find that the matter power spectrum measured from our super-cluster sample has at least twice as much power as that measured from our random sample. Our investigation of the effect of baryonic physics on the matter power spectrum is found to be in agreement with previous studies and is weaker than the selection effect over the majority of scales. In addition, we investigate the effect of targeting a cosmologically non-representative, super-cluster region of the sky on the weak lensing shear power spectrum. We do this by generating shear and convergence maps using a line of sight integration technique, which intercepts our random and super-cluster sub-volumes. We find the convergence power spectrum measured from our super-cluster sample has a larger amplitude than that measured from the random sample at all scales. We frame our results within the context of the Super-CLuster Assisted Shear Survey (Super-CLASS), which aims to measure the cosmic shear signal in the radio band by targeting a region of the sky that contains five Abell clusters. Assuming the Super-CLASS survey will have a source density of 1.5 galaxies/arcmin$^2$, we forecast a detection significance of $2.7^{+1.5}_{-1.2}$, which indicates that in the absence of systematics the Super-CLASS project could make a cosmic shear detection with radio data alone.