Analytic Prediction of Baryonic Effects from the EFT of Large Scale Structures

TL;DR

This paper develops an effective field theory framework to analytically predict baryonic effects on large-scale structure, matching simulations with high accuracy and enabling better understanding of baryonic physics in cosmology.

Contribution

It introduces a formalism to predict baryonic effects on the matter power spectrum using EFT, incorporating star-formation physics and long-wavelength displacements.

Findings

Predicted baryonic effects as a $k^2 P(k)$ correction with parameters linked to star-formation physics.

Achieved percent-level agreement with simulations up to high wavenumbers.

Provided a new analytical approach to understand and interface baryonic physics with cosmological data.

Abstract

The large scale structures of the universe will likely be the next leading source of cosmological information. It is therefore crucial to understand their behavior. The Effective Field Theory of Large Scale Structures provides a consistent way to perturbatively predict the clustering of dark matter at large distances. The fact that baryons move distances comparable to dark matter allows us to infer that baryons at large distances can be described in a similar formalism: the backreaction of short-distance non-linearities and of star-formation physics at long distances can be encapsulated in an effective stress tensor, characterized by a few parameters. The functional form of baryonic effects can therefore be predicted. In the power spectrum the leading contribution goes as $\propto k^2 P(k)$, with $P(k)$ being the linear power spectrum and with the numerical prefactor depending on the details of the star-formation physics. We also perform the resummation of the contribution of the long-wavelength displacements, allowing us to consistently predict the effect of the relative motion of baryons and dark matter. We compare our predictions with simulations that contain several implementations of baryonic physics, finding percent agreement up to relatively high wavenumbers such as $k\simeq 0.3\,h\, Mpc^{-1}$ or $k\simeq 0.6\, h\, Mpc^{-1}$, depending on the order of the calculation. Our results open a novel way to understand baryonic effects analytically, as well as to interface with simulations.