The Billion Galaxy Cosmological HI Large Deep Survey

TL;DR

This paper advocates for a large-scale, deep 21-cm HI survey of over a billion galaxies up to redshift 1.5, aiming to advance cosmology and dark energy research using next-generation radio arrays like the SKA.

Contribution

It proposes a comprehensive survey plan for the SKA to observe a vast number of galaxies, enabling new insights into cosmology and galaxy evolution.

Findings

Design of a large-scale HI survey for over a billion galaxies.

Potential to significantly improve understanding of dark energy.

Integration with multi-wavelength surveys for comprehensive science.

Abstract

We outline the case for a comprehensive wide and deep survey ultimately targeted at obtaining 21-cm HI line emission spectroscopic observations of more than a billion galaxies to redshift z=1.5 and greater over half the sky. This survey provides a database of galaxy redshifts, HI gas masses, and galaxy rotation curves that would enable a wide range of science, including fundamental cosmology and studies of Dark Energy. This science requires the next generation of radio arrays, which are being designed under the umbrella of the Square Kilometer Array (SKA) project. We present a science roadmap, extending to 2020 and beyond, that would enable this ambitious survey. We also place this survey in the context of other multi-wavelength surveys.