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arXiv · 2501.10504

(H)ALPing the 511 keV line: A thermal DM interpretation of the 511 keV emission

Mohammad Aghaie·Pedro De la Torre Luque·Alessandro Dondarini·Daniele Gaggero·Giulio Marino·Paolo Panci
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Abstract

We propose a novel framework where MeV-scale Dirac Dark Matter annihilates into axion-like particles, providing a natural explanation for the 511 keV gamma-ray line observed in the Galactic Center. The relic abundance is determined by p-wave annihilation into two axion-like particles, while s-wave annihilation into three axion-like particles, decaying into $e^+ e^-$ pairs, accounts for the line intensity. Remarkably, this model, assuming a standard Navarro-Frenk-White profile, reproduces the observed emission morphology, satisfies in-flight annihilation and cosmological bounds, and achieves the correct relic density, offering a compelling resolution to this longstanding anomaly.

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Mohammad Aghaie, Pedro De la Torre Luque, Alessandro Dondarini, Daniele Gaggero, Giulio Marino, Paolo Panci. 2026-03-18. (H)ALPing the 511 keV line: A thermal DM interpretation of the 511 keV emission. https://arxiv.org/abs/2501.10504

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