Extracting H I astrophysics from interferometric intensity mapping
Abstract
We present a new halo model of neutral hydrogen (H I) calibrated to galaxy formation simulations at redshifts z ∼ 0.1 and z ∼ 1.0 that we employ to investigate the constraining power of interferometric H I intensity mapping on H I astrophysics. We demonstrate that constraints on the small-scale H I power spectrum can break the degeneracy between the H I density $\Omega _{\rm H\, \small {I}}$ and the H I bias $b_{\rm H\, \small {I}}$ . For z ∼ 0.1, we forecast that an accurate measurement of $\Omega _{\rm H\, \small {I}}$ up to 6 per cent level precision and the large-scale H I bias $b_{\rm H\, \small {I}}^0$ up to 1 per cent 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 H I shot noise in the halo model framework in which a scatter of the relation between the H I mass of galaxies and their host halo mass is taken into account. Furthermore, given the number density of H I galaxies above a certain H I mass threshold, future surveys will also be able to constrain the H I mass function using only the H I shot noise. This will lead to constraints at the 10 per cent level using the standard Schechter function. This technique will potentially provide a new way of measuring the H I mass function, independent from existing methods. We predict that the SKA will be able to further improve the low-redshift constraints by a factor of 3, as well as pioneering measurements of H I astrophysics at higher redshifts.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- April 2021
- DOI:
- 10.1093/mnras/stab386
- arXiv:
- arXiv:2010.07985
- Bibcode:
- 2021MNRAS.502.5259C
- Keywords:
-
- techniques: interferometric;
- large-scale structure of Universe;
- radio lines: general;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- 19 pages, 11 figures and 6 tables. Updated to match the published version in MNRAS. For the computational tool used in this paper see arXiv:2009.14066 and https://halomod.readthedocs.io/en/latest/examples/extension.html