Constraining baryonic feedback and cosmology with weak-lensing, X-ray, and kinematic Sunyaev-Zeldovich observations

TL;DR

This paper uses combined weak-lensing, X-ray, and kSZ data to constrain baryonic feedback effects, revealing stronger feedback than simulations predict and reducing the tension between weak-lensing and Planck cosmological measurements.

Contribution

It introduces a seven-parameter baryonic feedback model constrained by multiple observations, improving understanding of feedback effects and their impact on cosmological parameters.

Findings

Baryonic feedback stronger than most simulations predict.

Significant suppression of matter power spectrum at small scales.

Reduced tension in $oldsymbol{ m extSigma_8}$ between weak-lensing and Planck data.

Abstract

Modern weak-lensing observations are becoming increasingly sensitive to baryonic feedback processes which are still poorly understood. So far, this challenge has been faced either by imposing scale-cuts in the data or by modelling baryonic effects with simple, one-parameter models. In this paper, we rely on a more general, seven-parameter prescription of baryonic feedback effects, which is primarily motivated by observations and has been shown to agree with a plethora of hydrodynamical simulations. By combining weak-lensing data from the Kilo-Degree Survey (KiDS-1000) with observations of gas around galaxy clusters, we are able to constrain baryonic parameters and learn more about feedback and cosmology. In particular, we use cluster gas fractions from X-ray data and gas profiles from kinematic Sunyaev-Zeldovich (kSZ) observations to provide evidence for baryonic feedback that is stronger than predicted by most hydrodynamical simulations. In terms of the matter power spectrum, we report a beyond-percent effect at wave-modes above $k\sim 0.1-0.45$ h/Mpc and a maximum suppression of $12-33$ percent at $k\sim7$ h/Mpc (68 percent confidence level). Regarding the combined parameter $\Sigma_8=\sigma_8(\Omega_m/0.3)^{0.58}$, we find the known tension with the Planck satellite data to be reduced from 3.8 to 2.9 $\sigma$ once baryonic effects are fully included in the analysis pipeline. The tension is further decreased to 2.6 $\sigma$ when the weak-lensing data is combined with X-ray and kSZ observations. We conclude that, while baryonic feedback effects become more important in modern weak-lensing surveys, they are unlikely to act as the main culprit for the observed $\Sigma_8$-tension.