Recovering Density Fields inside Quasar Proximity Zones at $z\sim 6$

TL;DR

This paper explores methods to accurately recover the matter density fluctuations within quasar proximity zones at high redshift, using synthetic spectra to understand the potential and limitations of this approach.

Contribution

It introduces a novel approach to reconstruct the density field inside quasar proximity zones at z~6 using simulations, accounting for systematics like continuum fitting.

Findings

Density can be recovered accurately with small scatter under ideal conditions.

Systematics such as continuum fitting impact the accuracy of density recovery.

Analysis of proximity zones can constrain quasar properties and environments.

Abstract

The matter density field at $z\sim 6$ is very challenging to probe. One of the traditional probes of the low density IGM that works successfully at lower redshifts is the Lyman-alpha forest in quasar spectra. However, at the end of reionization, the residual neutral hydrogen usually creates saturated absorption, thus much of the information about the gas density is lost. Luckily, in a quasar proximity zone, the ionizing radiation is exceptionally intense, thus creating a large region with non-zero transmitted flux. In this study we use the synthetic spectra from simulations to investigate how to recover the density fluctuations inside the quasar proximity zones. We show that, under ideal conditions, the density can be recovered accurately with a small scatter. We also discuss how systematics such as the quasar continuum fitting and reionization models affect the results. This study shows that by analyzing the absorption features inside quasar proximity zones we can potentially constrain quasar properties and the environments they reside in.