TAPIR Seminar

In person: 370 Cahill. To Join via Zoom: 864 8902 5566

ABSTRACT: Recent advancements in cosmological observations have provided an unprecedented opportunity to investigate the distribution of baryons relative to the underlying matter. In this talk, I will present pioneering work that uses a photometric survey (DESI imaging, DR10) to probe the stacked kinematic Sunyaev-Zel'dovich (kSZ) effect around luminous red galaxies (LRGs) and infer the distribution of baryons. Due to the large number of galaxies comprising the DESI imaging survey, this is also the highest signal-to-noise stacked kSZ measurement to date. Our analysis reveals a surprising amount of baryonic feedback, which significantly exceeds predictions from state-of-the-art hydrodynamical simulations such as IllustrisTNG. Therefore, of particular relevance to the astrophysical community is the potential to recalibrate large hydrodynamical simulations and bridge the gap between theory and observations. In addition, our finding bears important implications for the effect of baryons on the matter power spectrum and can thus help resolve hotly debated disparities between weak lensing surveys and cosmic microwave background (CMB) experiments such as "Lensing is low" and the "Low S8" tensions. Our measurement marks a critical step toward comprehending the complex interplay between baryons and the underlying matter.