Implications of SARAS3 data for Coulomb-like interacting dark matter
Abstract
The 21-cm signal from cosmic dawn is a potentially sensitive probe of interactions between dark matter (DM) and baryons. We investigate the implications of the SARAS3 non-detection in the 55.5-84.4 MHz band for Coulomb-like interacting DM (IDM). In contrast to earlier constraint analyses that focused primarily on baryon cooling, we model the interaction self-consistently by including both excess cooling of the gas and the suppression of structure formation, which delays the onset of star formation and hence suppresses the Lyα, X-ray, and ionizing backgrounds at early times. We perform a joint Bayesian fit of a global 21-cm signal model and a flexible foreground model to the SARAS3 antenna temperature, and find that the signal parameters remain weakly constrained after marginalizing over the foregrounds. The null result is nonetheless informative: the data disfavour deep absorption features within the observed band, with the strongest bound at z = 23.6 (ν≈ 57.7 MHz), where T21 ≳ −277.6 mK at 3σ. Comparing the IDM and standard cold dark matter scenarios, we find no statistically significant preference for IDM (Bayes factor B ≈ 1.7). While we do not constrain the strength of baryon-DM interactions, the SARAS3 non-detection places a meaningful upper bound on the amplitude of the global 21-cm signal in this class of models.
Versions
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BibTeX
@misc{mittal2026implications,
title = {{Implications of SARAS3 data for Coulomb-like interacting dark matter}},
author = {Shikhar Mittal and Prakhar Bansal and Harry Bevins and Saurabh Singh},
howpublished = {arXiv},
year = {2026},
month = aug,
doi = {10.48550/arxiv.2605.00991},
eprint = {2605.00991},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2605.00991},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Implications of SARAS3 data for Coulomb-like interacting dark matter
AU - Shikhar Mittal
AU - Prakhar Bansal
AU - Harry Bevins
AU - Saurabh Singh
PY - 2026
DA - 2026/08/29
PB - arXiv
DO - 10.48550/arxiv.2605.00991
UR - https://arxiv.org/abs/2605.00991
AB - The 21-cm signal from cosmic dawn is a potentially sensitive probe of interactions between dark matter (DM) and baryons. We investigate the implications of the SARAS3 non-detection in the 55.5-84.4 MHz band for Coulomb-like interacting DM (IDM). In contrast to earlier constraint analyses that focused primarily on baryon cooling, we model the interaction self-consistently by including both excess cooling of the gas and the suppression of structure formation, which delays the onset of star formation and hence suppresses the Lyα, X-ray, and ionizing backgrounds at early times. We perform a joint Bayesian fit of a global 21-cm signal model and a flexible foreground model to the SARAS3 antenna temperature, and find that the signal parameters remain weakly constrained after marginalizing over the foregrounds. The null result is nonetheless informative: the data disfavour deep absorption features within the observed band, with the strongest bound at z = 23.6 (ν≈ 57.7 MHz), where T_21 ≳ −277.6 mK at 3σ. Comparing the IDM and standard cold dark matter scenarios, we find no statistically significant preference for IDM (Bayes factor B ≈ 1.7). While we do not constrain the strength of baryon-DM interactions, the SARAS3 non-detection places a meaningful upper bound on the amplitude of the global 21-cm signal in this class of models.
ER -