Santos, Mario G.Bull, PhilipAlonso, DavidCamera, StefanoFerreira, Pedro G.Bernardi, GianniMaartens, RoyViel, MatteoVillaescusa-Navarro, FranciscoAbdalla, Filipe B.Jarvis, MattMetcalf, R. BentonPourtsidou, A.Wolz, Laura2015-10-202015-10-202014Santos, M.G. et al. (2014). Cosmology with a SKA HI intensity mapping survey. Paper presented at Advancing Astrophysics with the Square Kilometre Array, Giardini Naxos, Italy. PoS(AASKA14)0191824-8039http://hdl.handle.net/10566/1818Advancing Astrophysics with the Square Kilometre Array June 8-13, 2014 Giardini Naxos, ItalyHI intensity mapping (IM) is a novel technique capable of mapping the large-scale structure of the Universe in three dimensions and delivering exquisite constraints on cosmology, by using HI as a biased tracer of the dark matter density field. This is achieved by measuring the intensity of the redshifted 21cm line over the sky in a range of redshifts without the requirement to resolve individual galaxies. In this chapter, we investigate the potential of SKA1 to deliver HI intensity maps over a broad range of frequencies and a substantial fraction of the sky. By pinning down the baryon acoustic oscillation and redshift space distortion features in the matter power spectrum – thus determining the expansion and growth history of the Universe – these surveys can provide powerful tests of dark energy models and modifications to General Relativity. They can also be used to probe physics on extremely large scales, where precise measurements of spatial curvature and primordial non-Gaussianity can be used to test inflation; on small scales, by measuring the sum of neutrino masses; and at high redshifts where non-standard evolution models can be probed. We discuss the impact of foregrounds as well as various instrumental and survey design parameters on the achievable constraints. In particular we analyse the feasibility of using the SKA1 autocorrelations to probe the large-scale signal.enBased on the open access philosophy proceedings published on PoS can be read free of charge. No subscription nor registration is required of readers. This article can be accessed at http://pos.sissa.it/archive/conferences/215/019/AASKA14_019.pdfHI intensity mapping (IM)Large-scale structure of the universeGalaxiesSquare Kilometre Array (SKA)General RelativityNon-GaussianityConference Paper