# Halo nonlinear reconstruction

## TL;DR

This paper demonstrates that applying nonlinear reconstruction to simulated halo fields significantly enhances the scale at which linear signals can be recovered, promising improved BAO measurements in low-redshift surveys.

## Contribution

The study extends nonlinear reconstruction techniques to halo fields, showing improved scale recovery at low redshift and dense halo samples, with implications for BAO analysis.

## Key findings

- Improved the linear signal scale to $k\gtrsim0.36\ h\mathrm{Mpc}^{-1}$ for halo density $2.77\times 10^{-2}$ $(h^{-1} \mathrm{Mpc})^{-3}$.
- Achieved a factor of 2.29 improvement in scale, or 12 times more linear modes.
- The method's effectiveness decreases at higher redshift or lower halo density.

## Abstract

We apply the nonlinear reconstruction method to simulated halo fields. For halo number density $2.77\times 10^{-2}$ $(h^{-1} {\rm Mpc})^{-3}$ at $z=0$, corresponding to the SDSS main sample density, we find the scale where the noise saturates the linear signal is improved to $k\gtrsim0.36\ h {\rm Mpc}^{-1}$, a factor of $2.29$ improvement in scale, or $12$ in number of linear modes. The improvement is less for higher redshift or lower halo density. We expect this to substantially improve the BAO accuracy of dense, low redshift surveys, including the SDSS main sample, 6dFGS and 21cm intensity mapping initiatives.