KIPAC Seminar: Probing baryonic feedback with stacked kinetic Sunyaev-Zeldovich effect

Abstract: Understanding how baryons trace the underlying matter distribution remains one of the main challenges in precision cosmology. Recent high signal-to-noise measurements of the kinematic Sunyaev-Zeldovich (kSZ) effect now provide a powerful way to probe these diffuse baryons directly, and appear to imply very strong baryonic feedback. However, it is still unclear whether the theoretical modelling used so far is sufficiently detailed to describe the signal accurately. 

In this talk, I will present a comprehensive analysis of mock stacked kSZ measurements on realistic DESI-like galaxy samples based on hydrodynamic simulations that include non-linear physics and complex astrophysical processes. By separating the signal into its different components and isolating the processes that affect the density and velocity fields, I will identify the physical mechanisms that contribute to the kSZ signal and therefore need to be included in an accurate model. In particular, I will discuss the baryonic effects on density and velocity fields, the impact of the satellites in the galaxy sample, non-linear effects in the velocity field, and velocity reconstruction. I will show that at the precision of current data, ignoring satellites in the modeling biases low the inferred halo gas fractions; while with upcoming data, several other higher-order effects will become statistically significant. Accounting for these effects will be essential, given the precision of upcoming measurements, to extract reliable information about the gas distribution and robustly assess the strength of baryonic feedback in the Universe.