# A Robust BAO Extractor

## TL;DR

This paper introduces a fast, analytical method to extract and model the nonlinear evolution of Baryonic Acoustic Oscillations (BAO) from power spectra, applicable to simulations and real data without fitting parameters.

## Contribution

A novel BAO extractor operator that accurately models nonlinear effects across all scales without requiring fitted parameters from simulations.

## Key findings

- UV effects are irrelevant for the oscillating part's evolution.
- The method accurately reproduces BAO evolution down to redshift zero.
- The approach eliminates the need for fitting functions or nuisance parameters.

## Abstract

We define a procedure to extract the oscillating part of a given nonlinear Power Spectrum, and derive an equation describing its evolution including the leading effects at all scales. The intermediate scales are taken into account by standard perturbation theory, the long range (IR) displacements are included by using consistency relations, and the effect of small (UV) scales is included via effective coefficients computed in simulations. We show that the UV effects are irrelevant in the evolution of the oscillating part, while they play a crucial role in reproducing the smooth component. Our "extractor" operator can be applied to simulations and real data in order to extract the Baryonic Acoustic Oscillations (BAO) without any fitting function and nuisance parameter. We conclude that the nonlinear evolution of BAO can be accurately reproduced at all scales down to $z=0$ by our fast analytical method, without any need of extra parameters fitted from simulations.