Forecasts of cosmological constraints from HI intensity mapping with FAST, BINGO & SKA-I.

We forecast the cosmological constraints of the neutral hydrogen (HI) intensity mapping (IM) technique with radio telescopes by assuming 1-year of observational time. The current and future radio telescopes we consider here are FAST (Five hundred meter Aperture Spherical Telescope), BINGO (Baryon acoustic oscillations In Neutral Gas Observations), and SKA-I (Square Kilometre Array phase I) single-dish experiment. We also forecast the combined constraints of the three radio telescopes with Planck. We find that, the $1 \sigma$ errors of $(w_{0}, w_{a})$ for BINGO, FAST and SKA-I with respect to the fiducial values are respectively, $(0.9293, 3.5792), (0.4083, 1.5878), (0.3158, 0.4622)$. This is equivalent to $(56.04\%, 55.64\%)$ and $(66.02\%, 87.09\%)$ improvements in constraining $(w_{0}, w_{a})$ for FAST and SKA-I relative to BINGO. Simulations further show that SKA-I will put more stringent constraints than both FAST and BINGO when each of the experiment is combined with Planck measurement. For the $9$ cosmological parameters in consideration, we find that, there is a trade-off between SKA-I and FAST in constraining cosmological parameters, with each experiment being more superior in constraining a particular set of parameters.