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arXiv · 2607.17141

Unveiling dark energy properties with high-sensitivity cross-correlations of neutral hydrogen intensity mapping and galaxy surveys

Alessandro Marins·Chang Feng·Filipe B. Abdalla
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Abstract

The redshifted 21 cm line from the hyperfine structure of neutral hydrogen atoms is a promising tracer for the three-dimensional evolution of our universe. Its broad spatial and temporal coverage is crucial for understanding the complex nature of dark matter and dark energy. However, it is very challenging to directly detect the 21 cm signal due to the existence of radio foreground contaminants that are orders of magnitude brighter. Therefore, mitigating the foreground contamination becomes an indispensable task for detecting the 21 cm signal, which is also expected to be correlated with the dark-matter-dominated large-scale structure. The cross-correlations between the neutral hydrogen intensity mapping and galaxy surveys in the future can not only confirm a detection of the 21 cm signal but can also be a complementary probe for 21 cm cosmology. To meet the precision requirements for cosmological studies, it is important to investigate the complex features of the estimated cross-correlations using numerical simulations. In this work, we simulate the low-redshift HI observations and narrow-band optical surveys in the future and obtain the foreground- and bias-mitigated HI-galaxy cross-power spectra, with which we perform a Bayesian analysis to infer cosmological parameters of dynamical dark energy model. The method developed in this work will be important for cosmological studies with the 21 cm intensity mapping.

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Alessandro Marins, Chang Feng, Filipe B. Abdalla. 2026-07-19. Unveiling dark energy properties with high-sensitivity cross-correlations of neutral hydrogen intensity mapping and galaxy surveys. https://arxiv.org/abs/2607.17141

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