HI and cosmological constraints from intensity mapping, optical, and CMB surveys

TL;DR

This paper forecasts how upcoming intensity mapping, optical, and CMB surveys can precisely measure neutral hydrogen distribution and cosmological parameters, especially if foregrounds are well-controlled, enabling insights into the universe's structure and expansion.

Contribution

It presents new forecasts for constraints on HI and cosmology from near-term and future surveys, emphasizing the potential of cross-correlation techniques to mitigate systematics.

Findings

Surveys can measure HI density and bias with high precision.

Cross-correlation improves control over foregrounds and systematics.

SKA Phase 1 can detect the late-time ISW effect with high significance.

Abstract

We forecast constraints on neutral hydrogen (HI) and cosmological parameters using near-term intensity mapping surveys with instruments such as BINGO, MeerKAT, and the SKA, and Stage III and IV optical galaxy surveys. If foregrounds and systematic effects can be controlled - a problem which becomes much easier in cross-correlation - these surveys will provide exquisite measurements of the HI density and bias, as well as measurements of the growth of structure, the angular diameter distance, and the Hubble rate, over a wide range of redshift. We also investigate the possibility of detecting the late time ISW effect using the Planck satellite and forthcoming intensity mapping surveys, finding that a large sky survey with Phase 1 of the SKA can achieve a near optimal detection.