Cosmology with Intensity Mapping via Statistics Beyond the Power Spectrum in the SKAO Era
astro-ph.CO
Submitted: 2026-06-29
Updated: 2026-10-01
Comments: Published in Advancing Astrophysics with the SKA II (AASKAII), 2026 (arXiv:2606.20366). Report-no:AASKAII/Majumdar01. Advancing Astrophysics with the SKA II (AASKAII) outlines the transformative scientific advances that will be enabled by the SKA telescopes
License: http://creativecommons.org/licenses/by-nc-sa/4.0/
The gist: The cosmological distribution of neutral hydrogen (HI) during the post-reionization era is highly non-Gaussian due to the underlying non-linear structure formation, complex galaxy biasing, and
Terminology
Abstract
The cosmological distribution of neutral hydrogen (HI) during the post-reionization era is highly non-Gaussian due to the underlying non-linear structure formation, complex galaxy biasing, and potential primordial non-Gaussianity. One needs higher-order (beyond two-point) statistics to maximally extract the non-Gaussian information out of the 21-cm intensity maps. This chapter summarizes the potential of several higher-order statistics, including voxel intensity distribution, emission line stacking, probability density functions, 1-norm, bispectrum, and various marked statistics. Additionally, image-based morphological descriptors, such as the Largest Cluster Statistic, local dimensions, and Minkowski functionals, etc., can potentially characterize the morphology and geometry of the cosmic web encoded in the 21-cm intensity maps. This chapter presents forecasts of the detectability of these higher-order statistics in the context of the future SKAO observations. These forecasts incorporate instrumental noise, observational effects, and, in some cases, foreground removal in their analyses. With its unprecedented sensitivity, the future SKAO 21-cm observations will enable us to measure these higher-order statistics more precisely, possibly helping to break degeneracies between astrophysical and cosmological parameters, and maximizing the science outcome from these surveys.
Sources
- BINGO: a single dish approach to 21cm intensity mapping
- Breaking the intensity-bias degeneracy in line intensity mapping
- Probing the HI distribution at small scales using 21-cm Intensity Mapping at large scales
- Inflation and Early Dark Energy with a Stage II Hydrogen Intensity Mapping Experiment
- Cosmology from the Highly-Redshifted 21 cm Line
- Line-Intensity Mapping: 2017 Status Report
- SimBIG: Field-level Simulation-Based Inference of Galaxy Clustering
- Hybrid Summary Statistics
- Robust Morphological Measures for Large-Scale Structure in the Universe
- The HI intensity mapping power spectrum: insights from recent measurements
- Tracing Signatures of Modified Gravity in Redshift-Space Galaxy Bispectrum Multipoles: Prospects for Euclid
- Cosmological forecast from the full-sky angular power spectrum and bispectrum of 21cm intensity mapping
- Starobinsky in Stereo: SKA-CMB Synergy in SBI
- Large Scale Structure and the Cosmic Web
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