Year: 2026
Type: preprint
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.
Source: arXiv (Cornell University)
Authors: Anthony-Petersen, Robin, Ning, Orion, Watanabe, Yu, Safdi, Benjamin R., Dutra, Maíra, Calore, Francesca, Gallego, Savitri, Guan, William, Karwin, Christopher M., Kusenko, Alexander, Martinez-Castellanos, Israel, Matsumoto, Shigeki, Negro, Michela, Oberlack, Uwe, Rogers, Field R., Siegert, Thomas, Takahashi, Tadayuki, Xie, Haoyu, Yoneda, Hiroki, Zoglauer, Andreas, Boggs, Steven E., Hartmann, Dieter H., Kierans, Carolyn A., Tomsick, John A.
Institutions: Space Sciences Laboratory, University of California, Berkeley, Lawrence Berkeley National Laboratory, University of California, Los Angeles, Goddard Space Flight Center, Southeastern Universities Research Association, Centre National de la Recherche Scientifique, Laboratoire d'Annecy de Physique Théorique, Johannes Gutenberg University Mainz, Harvard University, Clemson University, Kavli Institute for the Physics and Mathematics of the Universe, The University of Tokyo, University of Maryland, College Park, Louisiana State University, University of Würzburg, University of California San Diego
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7221785642