Probing primordial non-Gaussianity with 21 cm fluctuations from minihalos

We investigate future constraints on primordial local-type non-Gaussianity from 21 cm angular power spectrum from minihalos. We particularly focus on the trispectrum of primordial curvature perturbations which are characterized by the non-linearity parameters $\tau_{\rm NL}$ and $g_{\rm NL}$. We show that future measurements of minihalo 21 cm angular power spectrum can probe these non-linearity parameters with an unprecedented precision of $\tau_{\rm NL}\sim30$ and $g_{\rm NL}\sim2\times10^3$ for Square Kilometre Array (SKA) and $\tau_{\rm NL}\sim0.6$ and $g_{\rm NL}\sim8\times10^2$ for Fast Fourier Transform Telescope (FFTT). These levels of sensitivity would give significant implications for models of the inflationary Universe and the origin of cosmic density fluctuations.