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Résumé |
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 paper, we extend the two-
fluid-like system up to two-loop order in perturbation theory. Along the way, we
show that a new linear counterterm proportional to the relative velocity of the
fluids could generically be present, but we show that its effects are expected to
be small in our universe. Regardless, we show how to consistently perform
perturbation theory in the presence of this new term. We find that the EFTofLSS at
two-loop order can accurately account for the details of baryonic processes on
large scales. We compare our results to a hydrodynamical N-body simulation at many
redshifts and 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 ℓ ≲ 2000. Our results are also
potentially
of interest for current and future weak lensing surveys. |
