Investigating cluster astrophysics and cosmology with cross-correlation of the thermal Sunyaev–Zel'dovich effect and weak lensing

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, α0, and the amplitude of the matter power spectrum, σ8, 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 σ8 ∼ 0.85 and a large fraction of non-thermal pressure (α0 ∼ 0.2–0.3). The tSZ–WL cross-correlation on the other hand prefers a significantly lower σ8 ∼ 0.6 and low α0 ∼ 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 haloes. In such a model, the combined data prefer σ8 ∼ 0.7 and α0 ∼ 0.2, consistent with predictions from hydrodynamical simulations.