21cm Cosmology

Abstract

Abstract.A new generation of radio telescopes with unprecedented capabilities for astronomy and fundamental physics will be in operation over the next few years. With high sensitivities and large fields of view, they are ideal for cosmological applications. We discuss their uses for cosmology focusing on the observational technique of HI intensity mapping, in particular at low redshifts (z < 4). This novel observational window promises to bring new insights for cosmology, in particular on ultra-large scales and at a redshift range that can go beyond the dark energy domination epoch. In terms of standard constraints on the dark energy equation of state, telescopes such as Phase I of the SKA should be able to obtain constrains about as well as a future galaxy redshift surveys. Statistical techniques to deal with foregrounds and calibration issues, as well as possible systematics are also discussed.

Impact of simulated 1/f noise for HI intensity mapping experiments

“…The benefits of HI IM are no bias in galaxy selection, intrinsic knowledge of redshift, and a higher surface brightness relative to galaxy surveys. HI IM has the potential to be one of the most important tools available to understanding the evolution of large-scale structure, as it contains several orders-of-magnitude more information than the CMB (Battye et al 2004;Masui et al 2010;Battye et al 2013;Santos et al 2014Santos et al , 2015Padmanabhan et al 2015;Bull et al 2015;Ma & Scott 2016).…”