2025/11/17 by Jiajun Zhang, Huanyuan Shan, Zhang, Jiajun +1
Physics and Astronomy · #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #Electrical and Electromagnetic Research #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena #Radio Astronomy Observations and Technology
paper · pdf · doi:10.48550/arxiv.2511.13370
openalex publication_date 2025/11/17 · openalex created_date 2025/11/19 · openalex updated_date 2026/07/28
The Epoch of Reionization (EoR) is a unique phase in cosmic history, marked by the ionization of neutral hydrogen by the first luminous sources. The global neutral hydrogen fraction (xHI) is a key observable for probing this era. This paper presents a novel, statistically robust method to extract the evolution of xHI from the challenging noise-dominated data from the Square Kilometre Array (SKA) Data Challenge 3b. Our approach is based on a key physical insight: the pixel value distribution in SKA intensity maps is a mixture of signals from ionized and neutral regions. We model this distribution as a superposition of two Gaussian components-one fixed at zero representing noise and ionized bubbles, and a second, offset Gaussian tracing the neutral hydrogen signal. We perform this decomposition on data grouped into three redshift bins. The double-Gaussian model provides an excellent fit to the pixel histogram data. The derived xHI values show a clear decreasing trend across the three redshift bins, consistent with a progressing reionization process. And the results are consistent with the provided simulation data. This method offers a powerful, model-independent, and fully interpretable way for measuring xHI from 21 cm data, demonstrating significant potential for application to future SKA observations.