Synergistic tests of inflation

Abstract: We investigate the possibility of utilising 21cm intensity mapping, optical galaxy, and Cosmic Microwave Background (CMB) surveys to constrain the power spectrum of primordial fluctuations predicted by single-field slow-roll inflation models. Implementing a Fisher forecast analysis, we derive constraints on the spectral tilt parameter $n_{\rm s}$ and its first and second runnings $(\alpha_{\rm s},\beta_{\rm s})$. We show that 21cm intensity mapping surveys with instruments like the Square Kilometre Array, CHIME, and HIRAX, can be powerful probes of the primordial features. We combine our forecasts with the ones derived for a COrE-like CMB survey, as well as for a Stage IV optical galaxy survey similar to Euclid. The synergies between different surveys can be exploited to rule out a large fraction of the available inflationary models.