# Investigating Cluster Astrophysics and Cosmology with Cross-Correlation of the Thermal Sunyaev-Zel'dovich Effect and Weak Lensing

## TL;DR

This paper uses measurements of the thermal Sunyaev-Zel'dovich effect and weak lensing to constrain galaxy cluster physics and cosmological parameters, revealing tensions that can be alleviated by modeling galaxy-halo relations.

## Contribution

It provides new constraints on the non-thermal pressure fraction and matter fluctuation amplitude by combining tSZ and weak lensing data with semi-analytic models.

## Key findings

- tSZ power spectrum prefers higher σ₈ (~0.85) and larger non-thermal pressure (~0.2-0.3)
- tSZ-WL cross-correlation prefers lower σ₈ (~0.6) and smaller non-thermal pressure (~0.05)
- Adjusting the stellar-mass-halo-mass relation slope reconciles the data, favoring σ₈ ~0.7 and α₀ ~0.2

## Abstract

Recent detections of the cross-correlation of the thermal Sunyaev-Zel'dovich (tSZ) effect and weak gravitational lensing (WL) enable unique studies of cluster astrophysics and cosmology. In this work, we present constraints on the amplitude of the non-thermal pressure fraction in galaxy clusters, $\alpha_0$, and the amplitude of the matter power spectrum, $\sigma_8$, using measurements of the tSZ power spectrum from Planck, and the tSZ-WL cross-correlation from Planck and the Red Cluster Sequence Lensing Survey. We fit the data to a semi-analytic model with the covariance matrix using $N$-body simulations. We find that the tSZ power spectrum alone prefers $\sigma_8 \sim 0.85$ and a large fraction of non-thermal pressure ($\alpha_0 \sim 0.2$-$0.3$). The tSZ-WL cross-correlation on the other hand prefers a significantly lower $\sigma_8 \sim 0.6$, and low $\alpha_0 \sim 0.05$. We show that this tension can be mitigated by allowing for a steep slope in the stellar-mass-halo-mass relation, which would cause a reduction of the gas in low-mass halos. In such a model, the combined data prefer $\sigma_8 \sim 0.7$ and $\alpha_0 \sim 0.2$, consistent with predictions from hydrodynamical simulations.