# The Reconstructed Power Spectrum in the Zeldovich Approximation

## TL;DR

This paper develops an analytical model for density reconstruction using the Zeldovich approximation, accurately fitting real and redshift-space data and improving understanding of BAO signal sharpening.

## Contribution

It introduces a comprehensive Zeldovich-based model including counterterms and bias terms up to quadratic order, fitting data across various scales and space configurations.

## Key findings

- Sub-percent agreement with N-body data in real and redshift space
- Effective modeling of BAO signal sharpening after reconstruction
- Comparison with existing models highlights improvements and higher bias effects.

## Abstract

Density-reconstruction sharpens the baryon acoustic oscillations signal by undoing some of the smoothing incurred by nonlinear structure formation. In this paper we present an analytical model for reconstruction based on the Zeldovich approximation, which for the first time includes a complete set of counterterms and bias terms up to quadratic order and can fit real and redshift-space data pre- and post-reconstruction data in both Fourier and configuration space over a wide range of scales. We compare our model to n-body data at $z = 0$ from the {\tt DarkSky} simulation \cite{skillman14}, finding sub-percent agreement in both real space and in the redshift-space power spectrum monopole out to $k = 0.4\ h$ Mpc$^{-1}$, and out to $k = 0.2\ h$ Mpc$^{-1}$ in the quadrupole, with comparable agreement in configuration space. We compare our model with several popular existing alternatives, updating existing theoretical results for exponential damping in wiggle/no-wiggle splits of the BAO signal and discuss the usually-ignored effect of higher bias contributions on the reconstructed signal. In the appendices, we re-derive the former within our formalism, present exploratory results on higher-order corrections due to nonlinearities inherent to reconstruction, and present numerical techniques with which to calculate the redshift-space power spectrum of biased tracers within the Zeldovich approximation.