In this talk, I shall review the most peculiar aspects of
cosmology in the radio band, with a special focus on the Square
Kilometre Array (SKA) radio-telescope and its pathfinders. I shall
present the main radio probes that can be exploited for late-time
cosmology: continuum and 21-cm line galaxy surveys, neutral hydrogen
intensity mapping, and even weak lensing cosmic shear at radio
frequencies. Moreover, I shall also discuss the added value of multi-
wavelength synergies, presenting some show-case example of the power of
radio-optical cross-correlations to test the fundaments of the
concordance cosmological model, such as the nature of dark matter and
dark energy, or tests of inflation and gravity.
Local contact: V. Pettorino
SAP