Constraining the z ≈ 1 neutral hydrogen (HI) distribution
Abstract
We constrain the z ≈ 1 HI distribution by jointly modeling two independent, existing observations of the 21-cm signal, the HI density parameter ΩHI measured using uGMRT by stacking the 21-cm emission from blue, star-forming galaxies, and the 21-cm autocorrelation power spectrum (PS) measured using CHIME. We assign HI to the dark matter halos in a cosmological simulation using an HI mass-halo mass (HIHM) relation with three free parameters whose values we estimate by performing a joint Bayesian inference comparing the simulated ΩHI and 21-cm PS with the measurements. We use the inferred HIHM posterior to simulate the HI distribution and predict the z ≈ 1 HI mass function (HIMF). We find that the HIMF remains nearly constant at low HI masses ( ≲ 3.6 × 109 M⊙), and it declines rapidly for larger HI masses. Around ∼ 90 percent of the total HI gas is contained in the mass range MHI ∈ [2 × 109, 4 × 1011] M⊙. Our estimates predict a larger abundance of high mass HI galaxies than predicted by earlier observations and hydrodynamical simulations. We expect these results to be useful in understanding galaxy evolution and star formation.
Versions
Related
- Cosmology beyond standard sirens: cross-correlation of gravitational waves and neutral hydrogen intensity mapping
- Constraining the Planetary Obliquity Distribution of Warm Jupiters
- Constraining the Delay Time Distribution of the r- and s-Process from Stellar Ages at Solar Metallicity
- A Direct Detection of Neutral Hydrogen Intensity Mapping on Mpc Scales at z ≈ 0.32 and z ≈ 0.44
- Constraining the Delay Time Distribution of the r - and s -process from Stellar Ages at Solar Metallicity
BibTeX
@misc{chhabra2026constraining,
title = {{Constraining the $z \approx 1$ neutral hydrogen (HI) distribution}},
author = {Minal Chhabra and Raghunath Ghara and Somnath Bharadwaj},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2607.24412},
eprint = {2607.24412},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2607.24412},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - Constraining the z ≈ 1 neutral hydrogen (HI) distribution
AU - Minal Chhabra
AU - Raghunath Ghara
AU - Somnath Bharadwaj
PY - 2026
DA - 2026/09/29
PB - arXiv
DO - 10.48550/arxiv.2607.24412
UR - https://arxiv.org/abs/2607.24412
AB - We constrain the z ≈ 1 HI distribution by jointly modeling two independent, existing observations of the 21-cm signal, the HI density parameter Ω_HI measured using uGMRT by stacking the 21-cm emission from blue, star-forming galaxies, and the 21-cm autocorrelation power spectrum (PS) measured using CHIME. We assign HI to the dark matter halos in a cosmological simulation using an HI mass-halo mass (HIHM) relation with three free parameters whose values we estimate by performing a joint Bayesian inference comparing the simulated Ω_HI and 21-cm PS with the measurements. We use the inferred HIHM posterior to simulate the HI distribution and predict the z ≈ 1 HI mass function (HIMF). We find that the HIMF remains nearly constant at low HI masses ( ≲ 3.6 × 10^9 M_⊙), and it declines rapidly for larger HI masses. Around ∼ 90 percent of the total HI gas is contained in the mass range M_HI ∈ [2 × 10^9, 4 × 10^11] M_⊙. Our estimates predict a larger abundance of high mass HI galaxies than predicted by earlier observations and hydrodynamical simulations. We expect these results to be useful in understanding galaxy evolution and star formation.
ER -