# Forecast for weighing neutrinos in cosmology with SKA

## TL;DR

This paper explores how SKA HI intensity mapping surveys can improve cosmological parameter constraints, especially on neutrino mass, when combined with current observations, highlighting significant improvements in matter density and Hubble constant estimates.

## Contribution

It demonstrates that SKA1 and SKA2 surveys can substantially enhance constraints on cosmological parameters, particularly on matter density and Hubble constant, with modest improvements on neutrino mass bounds.

## Key findings

- SKA surveys significantly improve constraints on Ω_m and H_0.
- SKA1 and SKA2 data improve neutrino mass constraints modestly.
- Constraints on neutrino mass vary slightly across mass hierarchies.

## Abstract

We investigate what role the SKA neutral hydrogen (HI) intensity mapping (IM) sky survey observation will play in weighing neutrinos in cosmology. We use the simulated data of the baryon acoustic oscillation (BAO) measurements from the HI IM survey based on SKA1 and SKA2 to do the analysis. For the current observations, we use the Planck 2015 cosmic microwave background (CMB) anisotropies observation, the optical BAO measurements, the type Ia supernovae (SN) observation (Pantheon compilation), and the latest $H_0$ measurement. We consider three mass ordering cases for massive neutrinos, i.e., the normal hierarchy (NH), inverted hierarchy (IH), and degenerate hierarchy (DH) cases. It is found that the SKA observation can significantly improve the constraints on $\Omega_{\rm m}$ and $H_0$. Compared to the current observation, the SKA1 data can improve the constraints on $\Omega_{\rm m}$ by about 33%, and on $H_0$ by about 36%; the SKA2 data can improve the constraints on $\Omega_{\rm m}$ by about 58%, and on $H_0$ by about 66%. It is also found that the SKA observation can only slightly improve the constraints on $\sum m_\nu$. Compared to the current observation, the SKA1 data can improve the constraints on $\sum m_\nu$ by about 4%, 3%, and 10%, for the NH, IH, and DH cases, respectively; the SKA2 data can improve the constraints on $\sum m_\nu$ by about 7%, 7%, and 16%, for the NH, IH, and DH cases, respectively.