HI galaxy simulations for the SKA: number counts and bias

TL;DR

This paper discusses the expected capabilities of SKA1 and SKA2 HI galaxy surveys, including galaxy counts and clustering bias, based on simulations, to inform cosmological forecasts.

Contribution

It provides detailed predictions of galaxy number densities and bias for SKA1 and SKA2 HI surveys, based on simulations and survey specifications.

Findings

SKA1 can detect about 5 million galaxies over 5,000 deg$^2$ up to z~0.8

SKA2 can detect about 1 billion galaxies over 30,000 deg$^2$ up to z~2.5

Survey predictions are used for cosmological forecasting

Abstract

This chapter describes the assumed specifications and sensitivities for HI galaxy surveys with SKA1 and SKA2. It addresses the expected galaxy number densities based on available simulations as well as the clustering bias over the underlying dark matter. It is shown that a SKA1 HI galaxy survey should be able to find around $5\times 10^6$ galaxies over 5,000 deg$^2$ (up to $z\sim 0.8$), while SKA2 should find $\sim 10^9$ galaxies over 30,000 deg$^2$ (up to $z\sim 2.5$). The numbers presented here have been used throughout the cosmology chapters for forecasting.