MeV dark matter decay forecasts for the COSI mission
Abstract
The decay of dark matter (DM) is a generic prediction of many particle physics models, producing distinctive monochromatic signatures in environments such as the Galactic halo. Searches for decaying DM in the elusive 'MeV gap' have remained conspicuously under-explored, despite well-motivated models including axion-like particles, sterile neutrinos, and hidden-sector scenarios predicting signatures in this energy range. The upcoming Compton Spectrometer and Imager (COSI) telescope will help bridge this gap. Designed to probe this energy band with high spectral resolution, low background, and wide field of view, COSI is well-suited for DM line searches at the MeV scale. In this work, we make projections for COSI's 2-year sensitivity for DM decay in the Milky Way halo using dedicated all-sky simulations incorporating COSI's predicted instrument response. We conclude that COSI will improve the sensitivity to the DM lifetime by more than an order of magnitude over the DM mass range 0.4 to 10 MeV.
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BibTeX
@misc{anthonypetersen2026dark,
title = {{MeV dark matter decay forecasts for the COSI mission}},
author = {Robin Anthony-Petersen and Orion Ning and Yu Watanabe and Benjamin R Safdi and Maíra Dutra and Francesca Calore and Savitri Gallego and William Guan and Christopher M Karwin and Alexander Kusenko and Israel Martinez-Castellanos and Shigeki Matsumoto and Michela Negro and Uwe Oberlack and Field R Rogers and Thomas Siegert and Tadayuki Takahashi and Haoyu Xie and Hiroki Yoneda and Andreas Zoglauer and Steven E Boggs and Dieter H Hartmann and Carolyn A Kierans and John A Tomsick},
howpublished = {HAL},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.17217},
eprint = {2610.17217},
archivePrefix = {arXiv},
url = {https://hal.science/hal-05842349v1},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - MeV dark matter decay forecasts for the COSI mission
AU - Robin Anthony-Petersen
AU - Orion Ning
AU - Yu Watanabe
AU - Benjamin R Safdi
AU - Maíra Dutra
AU - Francesca Calore
AU - Savitri Gallego
AU - William Guan
AU - Christopher M Karwin
AU - Alexander Kusenko
AU - Israel Martinez-Castellanos
AU - Shigeki Matsumoto
AU - Michela Negro
AU - Uwe Oberlack
AU - Field R Rogers
AU - Thomas Siegert
AU - Tadayuki Takahashi
AU - Haoyu Xie
AU - Hiroki Yoneda
AU - Andreas Zoglauer
AU - Steven E Boggs
AU - Dieter H Hartmann
AU - Carolyn A Kierans
AU - John A Tomsick
PY - 2026
DA - 2026/10/12
PB - HAL
DO - 10.48550/arxiv.2610.17217
UR - https://hal.science/hal-05842349v1
AB - The decay of dark matter (DM) is a generic prediction of many particle physics models, producing distinctive monochromatic signatures in environments such as the Galactic halo. Searches for decaying DM in the elusive 'MeV gap' have remained conspicuously under-explored, despite well-motivated models including axion-like particles, sterile neutrinos, and hidden-sector scenarios predicting signatures in this energy range. The upcoming Compton Spectrometer and Imager (COSI) telescope will help bridge this gap. Designed to probe this energy band with high spectral resolution, low background, and wide field of view, COSI is well-suited for DM line searches at the MeV scale. In this work, we make projections for COSI's 2-year sensitivity for DM decay in the Milky Way halo using dedicated all-sky simulations incorporating COSI's predicted instrument response. We conclude that COSI will improve the sensitivity to the DM lifetime by more than an order of magnitude over the DM mass range 0.4 to 10 MeV.
ER -