Forecasts on Primordial non-Gaussianity from 21 cm Intensity Mapping
  experiments
  We forecast ability of dedicated 21 cm intensity mapping experiments to
constraint primordial non-Gaussianity using power spectrum and bispectrum. We
model the signal including the non-linear biasing expansion using a generalized
halo model approach. We consider the importance of foreground filtering scale
and of the foreground wedge. We find that the current generation intensity
mapping experiments like CHIME do not posses sufficient sensitivity to be
competitive with the existing limits. On the other hand, upcoming experiments
like HIRAX can improve the current constraints and the proposed PUMA experiment
can substantially improve them, reaching sensitivities below $\sigma (f_{\rm
NL})<5$ for equilateral and orthogonal configurations and $\sigma( f_{\rm NL})
< 1$ for the local shape if good foreground control is achieved.
