# Data Analysis for Precision 21 cm Cosmology

## TL;DR

This paper reviews the latest data analysis techniques in 21 cm cosmology, emphasizing the importance of software algorithms alongside hardware for successful large-scale universe surveys.

## Contribution

It provides a comprehensive, pedagogical overview of current data analysis methods used in 21 cm cosmology, from calibration to parameter estimation.

## Key findings

- Advances in calibration techniques improve data accuracy.
- Foreground subtraction methods are crucial for signal isolation.
- Pipeline steps are essential for extracting cosmological information.

## Abstract

The redshifted 21 cm line is an emerging tool in cosmology, in principle permitting three-dimensional surveys of our Universe that reach unprecedentedly large volumes, previously inaccessible length scales, and hitherto unexplored epochs of our cosmic timeline. Large radio telescopes have been constructed for this purpose, and in recent years there has been considerable progress in transforming 21 cm cosmology from a field of considerable theoretical promise to one of observational reality. Increasingly, practitioners in the field are coming to the realization that the success of observational 21cm cosmology will hinge on software algorithms and analysis pipelines just as much as it does on careful hardware design and telescope construction. This review provides a pedagogical introduction to state-of-the-art ideas in 21 cm data analysis, covering a wide variety of steps in a typical analysis pipeline, from calibration to foreground subtraction to mapmaking to power spectrum estimation to parameter estimation.