Forecast for weighing neutrinos in cosmology with SKA

We investigate what role the SKA neutral hydrogen (HI) intensity mapping (IM) and galaxy sky surveys will play in weighing neutrinos in cosmology. We use the simulated data of the baryon acoustic oscillation (BAO) measurements from the HI surveys based on SKA1 (IM) and SKA2 (galaxy) 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(m) and H-0. Compared to the current observation, the SKA1 data can improve the constraints on omega(m) by about 33%, and on H-0 by about 36%; the SKA2 data can improve the constraints on omega(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 n-ary sumation m(v). Compared to the current observation, the SKA1 data can improve the constraints on n-ary sumation m(v) by about 4%, 3%, and 10%, for the NH, IH, and DH cases, respectively; the SKA2 data can improve the constraints on n-ary sumation m(v) by about 7%, 7%, and 16%, for the NH, IH, and DH cases, respectively.