Title: Solving big-scale problems with small-scale physics
Abstract:
Recent advancements in cosmological observations have provided an unprecedented opportunity to investigate the distribution of gas relative to the underlying dark matter, allowing us to tackle a number of interesting problems in cosmology and also build a complete, multi-scale picture of galaxy formation and evolution. In this talk, I will present pioneering work that uses the photometric survey of the Dark Energy Spectroscopic Instrument (DESI) to probe the stacked kinematic Sunyaev-Zel'dovich (kSZ) effect and infer the distribution of gas in the Universe. Our analysis reveals a surprising amount of baryonic feedback, which significantly exceeds predictions from state-of-the-art hydrodynamical simulations such as IllustrisTNG. As making measurements of the gas at low densities and low temperatures has been challenging until now, our measurement provides an important and viable path towards calibrating large hydrodynamical simulations and bridging 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 inconsistencies in cosmology such as the "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.
Speaker:
Boryana Hadzhiyska (University of California, Berkeley and Lawrence Berkeley National Laboratory)
