2020/06/30 by Garima Chauhan, Claudia del P. Lagos, Adam R. H. Stevens +3 · 1 citation
Physics and Astronomy · #astro-ph.GA
paper · pdf · doi:10.1093/mnras/staa2251
Accepted for publication in MNRAS
arxiv created 2020/07/28 · arxiv updated 2020/08/12
We use SHARK, a semi-analytic galaxy formation model, to investigate the physical processes involved in dictating the shape, scatter and evolution of the HI-halo mass relation at 0≤ z ≤ 2. We compare SHARK with HI clustering and spectral stacking of the HI-halo mass relation derived from observations finding excellent agreement with the former and a deficiency of HI in SHARK at M\rm vir≈ 1012-13 M\odot in the latter, but otherwise great agreement below and above that mass threshold. In SHARK, we find that the HI mass increases with the halo mass up to a critical mass of ≈ 1011.8 M\odot; between ∼ 1011.8-1013M\odot, the scatter in the relation increases by 0.7 dex and the HI mass decreases with the halo mass on average; at M\rm vir ≥ 1013 M\odot, the HI content continues to increase with halo mass. We find that the critical halo mass of ≈ 1012 M\odot is largely set by feedback from Active Galactic Nuclei (AGN), and the exact shape and scatter of the HI-halo mass relation around that mass is extremely sensitive to how AGN feedback is modelled, with other physical processes playing a less significant role. We determine the main secondary parameters responsible for the scatter of the HI-halo mass relation, namely the halo spin parameter at M\rm vir≤ 1011.8 M\odot, and the fractional contribution from substructure to the total halo mass for M\rm vir≥ 1013 M\odot. The scatter at 1011.8<M\rm vir<1013 M\odot is best described by the black-hole-to-stellar mass ratio of the central galaxy, reflecting the AGN feedback relevance. We present a numerical model to populate dark matter-only simulations with HI at 0≤ z ≤ 2 based solely on halo parameters that are measurable in such simulations.