# Effects of baryons on weak lensing peak statistics

## TL;DR

This study examines how baryonic feedback, especially from AGN, impacts weak lensing peak statistics in convergence maps, highlighting the importance of smoothing scale choices for future surveys like DES and Euclid.

## Contribution

It provides a detailed analysis of baryonic effects on weak lensing peaks using simulations and the baryonic correction model, emphasizing the dependence on smoothing scale.

## Key findings

- Baryonic effects significantly depend on the smoothing scale applied.
- A smoothing of 8 arcmin suffices for DES-like surveys to mitigate baryonic impact.
- A smoothing of 16 arcmin is needed for Euclid-like surveys to control baryonic suppression.

## Abstract

Upcoming weak-lensing surveys have the potential to become leading cosmological probes provided all systematic effects are under control. Recently, the ejection of gas due to feedback energy from active galactic nuclei (AGN) has been identified as major source of uncertainty, challenging the success of future weak-lensing probes in terms of cosmology. In this paper we investigate the effects of baryons on the number of weak-lensing peaks in the convergence field. Our analysis is based on full-sky convergence maps constructed via light-cones from $N$-body simulations, and we rely on the baryonic correction model of Schneider et al. (2019) to model the baryonic effects on the density field. As a result we find that the baryonic effects strongly depend on the Gaussian smoothing applied to the convergence map. For a DES-like survey setup, a smoothing of $\theta_k\gtrsim8$ arcmin is sufficient to keep the baryon signal below the expected statistical error. Smaller smoothing scales lead to a significant suppression of high peaks (with signal-to-noise above 2), while lower peaks are not affected. The situation is more severe for a Euclid-like setup, where a smoothing of $\theta_k\gtrsim16$ arcmin is required to keep the baryonic suppression signal below the statistical error. Smaller smoothing scales require a full modelling of baryonic effects since both low and high peaks are strongly affected by baryonic feedback.