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Main Authors: Chen, Kai-Feng, Neyer, Meredith, Hewitt, Jacqueline N., Smith, Aaron, Vogelsberger, Mark
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2510.07374
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author Chen, Kai-Feng
Neyer, Meredith
Hewitt, Jacqueline N.
Smith, Aaron
Vogelsberger, Mark
author_facet Chen, Kai-Feng
Neyer, Meredith
Hewitt, Jacqueline N.
Smith, Aaron
Vogelsberger, Mark
contents Observations of the redshifted 21-cm line during the Epoch of Reionization will open a new window to probe the intergalactic medium during the formation of the first stars, galaxies, and black holes. A particularly promising route to an initial detection is to cross-correlate tomographic 21-cm maps with spectroscopically confirmed Lyman-$α$ emitters (LAEs). High-redshift LAEs preferentially reside in ionized bubbles that are strongly anticorrelated with the surrounding neutral regions traced by 21-cm observations. In this work, we study the prospect of detecting such a cross-correlation signal by stacking 21-cm image cubes around LAEs using a current-generation 21-cm instrument -- the Hydrogen Epoch of Reionization Array (HERA). Our forecast adopts a realistic mapping pipeline to generate foreground-free 21-cm image cubes. The statistical properties of these images, arising from the complex instrumental response, are carefully accounted for. We further introduce a physically motivated signal template calibrated on the THESAN radiation-hydrodynamic simulations, which connects the cross-correlation amplitude to the global neutral fraction. Our results show that a sample of ~50 spectroscopically confirmed LAEs is sufficient to begin constraining the reionization history. These results represent an important preparatory step toward joint analyses of 21-cm experiments with upcoming wide-area, high-redshift galaxy surveys from Euclid and the Nancy Grace Roman Space Telescope.
format Preprint
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institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Stacking 21-cm Maps around Lyman-$α$ Emitters during Reionization: Prospects for a Cross-correlation Detection with the Hydrogen Epoch of Reionization Array
Chen, Kai-Feng
Neyer, Meredith
Hewitt, Jacqueline N.
Smith, Aaron
Vogelsberger, Mark
Cosmology and Nongalactic Astrophysics
Astrophysics of Galaxies
Observations of the redshifted 21-cm line during the Epoch of Reionization will open a new window to probe the intergalactic medium during the formation of the first stars, galaxies, and black holes. A particularly promising route to an initial detection is to cross-correlate tomographic 21-cm maps with spectroscopically confirmed Lyman-$α$ emitters (LAEs). High-redshift LAEs preferentially reside in ionized bubbles that are strongly anticorrelated with the surrounding neutral regions traced by 21-cm observations. In this work, we study the prospect of detecting such a cross-correlation signal by stacking 21-cm image cubes around LAEs using a current-generation 21-cm instrument -- the Hydrogen Epoch of Reionization Array (HERA). Our forecast adopts a realistic mapping pipeline to generate foreground-free 21-cm image cubes. The statistical properties of these images, arising from the complex instrumental response, are carefully accounted for. We further introduce a physically motivated signal template calibrated on the THESAN radiation-hydrodynamic simulations, which connects the cross-correlation amplitude to the global neutral fraction. Our results show that a sample of ~50 spectroscopically confirmed LAEs is sufficient to begin constraining the reionization history. These results represent an important preparatory step toward joint analyses of 21-cm experiments with upcoming wide-area, high-redshift galaxy surveys from Euclid and the Nancy Grace Roman Space Telescope.
title Stacking 21-cm Maps around Lyman-$α$ Emitters during Reionization: Prospects for a Cross-correlation Detection with the Hydrogen Epoch of Reionization Array
topic Cosmology and Nongalactic Astrophysics
Astrophysics of Galaxies
url https://arxiv.org/abs/2510.07374