## CPC Seminar: Baryonic effects in the Effective Field Theory of Large-Scale Structure and an analytic recipe for lensing in CMB-S4

• May 10, 2021, 2:00 pm US/Central
• Matthew Lewandowski, Northwestern

Abstract: Upcoming Large-Scale Structure surveys will likely become the next leading sources of cosmological information, making it crucial to have a precise understanding of the influence of baryons on cosmological observables. The Effective Field Theory of Large-Scale Structure (EFTofLSS) provides a consistent way to predict the clustering of dark matter and baryons on large scales, where their leading corrections in perturbation theory are given by a simple and calculable functional form even after the onset of baryonic processes. In this talk, I discuss theoretical developments in the perturbation theory of the two-fluid-like system, including a discussion of a new linear counterterm proportional to the relative velocity of the fluids.  I will discuss how the EFTofLSS at two-loop order can accurately account for the details of baryonic processes on large scales by comparing our results to a hydrodynamical N-body simulation at many redshifts.  We find that the counterterms associated with the leading corrections to dark matter and baryons start to differ between redshifts z ≈ 3 and z ≈ 2, signaling the onset of star-formation physics.  We then use these fits to compute the lensing power spectrum, show that the understanding of baryonic processes will be important for analyzing CMB-S4 data, and show that the two-loop EFTofLSS accurately captures these effects for $\ell \lesssim 2000$.