Constraining baryonic feedback with kinematic Sunyaev Zel'dovich signal

Lurdes Ondaro Mallea

Abstract: The distribution of gas relative to the underlying matter is a major unknown in current cosmology, posing strong challenges to the next generation of large-scale structure surveys, particularly weak lensing studies. With the advent of recent high-quality observations of the kinematic Sunyaev-Zeldovich (kSZ) effect, we can directly measure the gas distribution in the outskirts of haloes for the first time. These measurements, proportional to the momentum field of gas, suggest that the gas is much more extended than dark matter, pointing to strong feedback from supermassive black holes. In this talk, I will show how several baryonic processes shape the density and velocity fields of gas and propose a flexible model for the kSZ signal. Using the state-of-the-art FLAMINGO simulation suite, we find that powerful outflows sourced by feedback events transport gas to the outskirts of haloes, with large outflowing velocities, affecting both density and velocity fields of gas to several Mpc scales. Motivated by these insights, I will present a physically-motivated model that can simultaneously fit the kSZ signal and power spectrum suppression due to baryonic effects of all FLAMINGO variations, at the 20% and 1% levels respectively. Remarkably, the model predicts the correct gas fractions in all halo masses from weak to strong feedback scenarios. This model will be a valuable tool in future kSZ + weak lensing analysis, helping to constrain astrophysical processes such as feedback from supermassive black holes and towards reliable cosmological inference.