Jurek tells us about the prospects for constraining axion (aka ultralight aka fuzzy) dark matter with future 21cm intensity mapping survey such as SKA and HIRAX.
Axion models arising from specific energy scales predict that an axion with a given mass will only provide a certain fraction of the total dark matter. It seems plausible that with SKA we will be able to detect ultralight dark matter even if it arises from a GUT scale axion model. An observational noise model for SKA was included to make this claim, but as of yet no theoretical uncertainty is included in the calculation.
Cosmology Talks 