Probing baryonic feedback with the kinematic Sunyaev–Zeldovich Effect
Lurdes Ondaro Mallea (Institute of Astronomy, Cambridge)
Wednesday 20/05/2026 @ 14:00, Sala Antonio Sollima (IV piano Battiferro)
Understanding how baryons trace the underlying dark matter distribution remains one of the main challenges in precision cosmology. As next-generation surveys such as Euclid Consortium, Vera C. Rubin Observatory, and Simons Observatory reach percent-level precision, baryonic feedback has become a major source of uncertainty in large-scale structure analyses. Recent high signal-to-noise measurements of the kinematic Sunyaev-Zeldovich (kSZ) effect now provide a powerful way to probe diffuse baryons directly. These measurements appear to imply very strong baryonic feedback, somewhat in tension with previous X-ray observations. However, it remains 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 stacked kSZ measurements using realistic mock observations from the FLAMINGO simulations. I will show that baryonic feedback produces significant modifications not only to the gas distribution but also to the velocity field. I will further identify the physical mechanisms that contribute to the kSZ signal and therefore need to be included in a successful model. In particular, I will discuss the impact of satellite galaxies and non-linearities in the velocity field, both in idealized and more realistic scenarios. Accounting for these effects will be essential, given the precision of upcoming measurements, to extract reliable information about the gas distribution and constrain the strength of baryonic feedback in the Universe.