Baryonic feedback is a leading contaminant in studying dark matter and cosmology using cosmic shear. This has meant omitting much of the data during cosmological inference, or forward-modeling the spatial distribution of gas around dark matter halos using analytical or hydrodynamical models for baryonic feedback, which introduces nuisance parameters and model dependence. We propose a novel method of ``baryon nulling'' using cross-correlations between shear maps and fast radio burst (FRB) dispersion measures. By directly subtracting the dark matter--dispersion measure cross-correlation, the sensitivity of our nulled power spectra to feedback effects can be significantly reduced without any explicit feedback modeling. Using the FLAMINGO suite of hydrodynamic simulations, whose power spectra span a wide yet realistic range of feedback variations, we demonstrate that our method reduces sensitivity to feedback modeling at k≈1 Mpc−1 by about an order of magnitude. This points toward a strong synergy between the next generation of sensitive FRB surveys such as CHORD and the DSA-2000, and cosmic shear surveys such as Rubin, Euclid, and Roman.
@article{arxiv.2509.19514,
title = {Nulling baryonic feedback in weak lensing surveys using cross-correlations with fast radio bursts},
author = {Calvin Leung and Josh Borrow and Kiyoshi W. Masui and Shion Andrew and Kai-Feng Chen and Joop Schaye and Matthieu Schaller},
journal= {arXiv preprint arXiv:2509.19514},
year = {2025}
}