Neutral hydrogen in the post-reionization universe

TL;DR

This paper presents a data-driven halo model for neutral hydrogen distribution from redshift 0 to 5, integrating diverse observational data to improve understanding of cosmic evolution and aid future surveys.

Contribution

It introduces a comprehensive halo model fitted to multiple observational datasets, enabling detailed study of HI evolution and clustering across a broad redshift range.

Findings

Best-fitting parameters for HI distribution derived from diverse data

Model accurately describes HI abundance and clustering from z=0 to 5

Framework useful for forecasting and extending to other line transitions

Abstract

The evolution of neutral hydrogen (HI) across redshifts is a powerful probe of cosmology, large scale structure in the universe and the intergalactic medium. Using a data-driven halo model to describe the distribution of HI in the post-reionization universe ($z \sim $ 5 to 0), we obtain the best-fitting parameters from a rich sample of observational data: low redshift 21-cm emission line studies, intermediate redshift intensity mapping experiments, and higher redshift Damped Lyman Alpha (DLA) observations. Our model describes the abundance and clustering of neutral hydrogen across redshifts 0 - 5, and is useful for investigating different aspects of galaxy evolution and for comparison with hydrodynamical simulations. The framework can be applied for forecasting future observations with neutral hydrogen, and extended to the case of intensity mapping with molecular and other line transitions at intermediate redshifts.