Strong Constraints on Line Signals from Dark Matter Annihilation in a Nearby Subhalo
Abstract
We present a dedicated search for monochromatic gamma-ray emission from a recently proposed nearby dark matter subhalo candidate. Using nearly 15 years of Fermi-LAT Pass 8 data, we perform a sliding-window search for gamma-ray lines between 10 and 300 GeV. We do not find any statistically significant evidence for a line signal. The largest excess occurs at Eγ≃ 28 GeV with a local significance of 2.5σ. We therefore derive 95% confidence level upper limits on the annihilation cross section for χχ→ γγ. Under the assumed NFW subhalo model, the resulting constraints are stronger than existing Galactic Center line limits over much of the explored mass range. We further translate these line constraints into bounds on well-motivated WIMP models, such as Higgs-portal and Wino dark matter scenarios, restricting previously open parameter regions consistent with thermal freeze-out as well as models associated with dark matter interpretations of the Galactic Center Excess.
Related
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BibTeX
@misc{perez2026strong,
title = {{Strong Constraints on Line Signals from Dark Matter Annihilation in a Nearby Subhalo}},
author = {Asier Salces Pérez and Thong T. Q. Nguyen and Pedro De la Torre Luque and Tim Linden},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.03016},
eprint = {2609.03016},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.03016},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Strong Constraints on Line Signals from Dark Matter Annihilation in a Nearby Subhalo
AU - Asier Salces Pérez
AU - Thong T. Q. Nguyen
AU - Pedro De la Torre Luque
AU - Tim Linden
PY - 2026
DA - 2026/09/04
PB - arXiv
DO - 10.48550/arxiv.2609.03016
UR - https://arxiv.org/abs/2609.03016
AB - We present a dedicated search for monochromatic gamma-ray emission from a recently proposed nearby dark matter subhalo candidate. Using nearly 15 years of Fermi-LAT Pass 8 data, we perform a sliding-window search for gamma-ray lines between 10 and 300 GeV. We do not find any statistically significant evidence for a line signal. The largest excess occurs at E_γ≃ 28 GeV with a local significance of 2.5σ. We therefore derive 95% confidence level upper limits on the annihilation cross section for χχ→ γγ. Under the assumed NFW subhalo model, the resulting constraints are stronger than existing Galactic Center line limits over much of the explored mass range. We further translate these line constraints into bounds on well-motivated WIMP models, such as Higgs-portal and Wino dark matter scenarios, restricting previously open parameter regions consistent with thermal freeze-out as well as models associated with dark matter interpretations of the Galactic Center Excess.
ER -