21-cm Constraints on S-wave Dark Matter Annihilation with Subhalo-enhanced Effects
Abstract
Observations of the 21-cm signal can probe energy injection into the intergalactic medium arising from dark matter annihilation during cosmic dawn and reionization. For s-wave annihilation, the annihilation rate depends on the squared dark matter density, making the 21-cm signal sensitive to dark matter halo substructure. In this work, we extend the numerical method of DM21cm to address spatially inhomogeneous s-wave annihilation including subhalo effects, using semi-analytical treatment of SASHIMI-C. Our numerical results show that the projected HERA limit for the γγ annihilation channel is stronger than the Leo~T bound within the dark matter mass range of mχ≤ 3 keV, whereas the projected HERA limit for the e+e- annihilation channel is the strongest among the existing bounds for mχ∼ 0.1--1 GeV.
Related
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BibTeX
@misc{xu202621cm,
title = {{21-cm Constraints on S-wave Dark Matter Annihilation with Subhalo-enhanced Effects}},
author = {Zixuan Xu and Sibo Zheng},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.21479},
eprint = {2609.21479},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.21479},
}
RIS
TY - UNPB
TI - 21-cm Constraints on S-wave Dark Matter Annihilation with Subhalo-enhanced Effects
AU - Zixuan Xu
AU - Sibo Zheng
PY - 2026
DA - 2026/09/18
PB - arXiv
DO - 10.48550/arxiv.2609.21479
UR - https://arxiv.org/abs/2609.21479
AB - Observations of the 21-cm signal can probe energy injection into the intergalactic medium arising from dark matter annihilation during cosmic dawn and reionization. For s-wave annihilation, the annihilation rate depends on the squared dark matter density, making the 21-cm signal sensitive to dark matter halo substructure. In this work, we extend the numerical method of DM21cm to address spatially inhomogeneous s-wave annihilation including subhalo effects, using semi-analytical treatment of SASHIMI-C. Our numerical results show that the projected HERA limit for the γγ annihilation channel is stronger than the Leo~T bound within the dark matter mass range of m_χ≤ 3 keV, whereas the projected HERA limit for the e^+e^- annihilation channel is the strongest among the existing bounds for m_χ∼ 0.1--1 GeV.
ER -