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

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 reproduces the observed emission morphology, satisfies in-flight annihilation and cosmological bounds, and achieves the correct relic density, assuming a contracted Navarro-Frenk-White profile similar to the one that reproduces the Fermi-LAT Galactic Center Excess, offering a compelling resolution to this longstanding anomaly.