Atomic hydrogen in z=0 galaxies in the COLIBRE simulations

@misc{oman2026atomic,
  title = {{Atomic hydrogen in $z=0$ galaxies in the COLIBRE simulations}},
  author = {Kyle A. Oman and Ruby J. Wright and Andrea Gebek and Diego Dado and Katherine E. Harborne and Evgenii Chaikin and Carlos S. Frenk and Filip Huško and Claudia D. P. Lagos and Aaron D. Ludlow and Sylvia Ploeckinger and Alexander J. Richings and Matthieu Schaller and Joop Schaye and James W. Trayford},
  howpublished = {arXiv},
  year = {2026},
  month = oct,
  doi = {10.48550/arxiv.2610.18046},
  eprint = {2610.18046},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2610.18046},
  note = {CC BY 4.0},
}

TY  - UNPB
TI  - Atomic hydrogen in z=0 galaxies in the COLIBRE simulations
AU  - Kyle A. Oman
AU  - Ruby J. Wright
AU  - Andrea Gebek
AU  - Diego Dado
AU  - Katherine E. Harborne
AU  - Evgenii Chaikin
AU  - Carlos S. Frenk
AU  - Filip Huško
AU  - Claudia D. P. Lagos
AU  - Aaron D. Ludlow
AU  - Sylvia Ploeckinger
AU  - Alexander J. Richings
AU  - Matthieu Schaller
AU  - Joop Schaye
AU  - James W. Trayford
PY  - 2026
DA  - 2026/10/13
PB  - arXiv
DO  - 10.48550/arxiv.2610.18046
UR  - https://arxiv.org/abs/2610.18046
AB  - We present an overview of the properties of atomic hydrogen (HI) in galaxies at redshift z=0 in the COLIBRE cosmological galaxy formation simulations. COLIBRE directly simulates the multi-phase interstellar medium (ISM) and includes new methods to follow radiative cooling to ≈ 10 K, non-equilibrium chemistry coupled to dust, and dust formation, growth \& destruction. We focus on the (200 cMpc)^3 volume with resolution elements of 2× 10^6 M_⊙. No HI properties informed the calibration of model parameters and yet we find very good agreement with the observed M_⋆-M_HI relation, the HI mass and velocity width functions, the HI mass-size relation, and (baryonic) Tully-Fisher relations, albeit with some mismatches at the extremes of the galaxy population. HI surface density profiles are realistic, except at large radii around massive (M_⋆≳ 10^10 M_⊙) galaxies where we find a population of possibly spurious circumgalactic HI clouds, whose abundances and masses decrease, however, with increasing mass resolution). Using smaller simulations to vary some of the uncertain model parameters, we find that the main scaling relations are at most mildly affected, although this may not extend to detailed HI morphokinematics. Convergence across mass resolution levels a factor of $8$ higher and lower is good: the median HI mass and HI `occupation fraction' as a function of halo mass, and the HI mass function, are remarkably stable, although the highest resolution model overproduces HI sources by a factor of ≈2 at M_HI≳ 3× 10^9 M_⊙. Upturns in the low-mass and low-velocity slopes of the HI mass and velocity width functions with potentially subtle observational signatures are predicted.
ER  -