Extracting HI Astrophysics from Interferometric Intensity Mapping

Understand

We present a new halo model of neutral hydrogen (HI) calibrated to galaxy formation simulations at redshifts $z\sim0.1$ and $z\sim1.0$ that we employ to investigate the constraining power of interferometric HI intensity mapping on HI astrophysics.

• We demonstrate that constraints on the small-scale HI power spectrum can break the degeneracy between the HI density $\Omega_{\rm HI}$ and the HI bias $b_{\rm HI}$.
• For $z\sim0.1$, we forecast that an accurate measurement of $\Omega_{\rm HI}$ up to 6% level precision and the large-scale HI bias $b_{\rm HI}^0$ up to 1% level precision can be achieved using Square Kilometre Array (SKA) pathfinder data from MeerKAT and Australian SKA Pathfinder (ASKAP).
• We also propose a new description of the HI shot noise in the halo model framework in which a scatter of the relation between the HI mass of galaxies and their host halo mass is taken into account.