Exciting dark matter and the INTEGRAL/SPI 511 keV signal

2007/02/28 by Douglas P. Finkbeiner, Neal Weiner · 26 citations
Physics and Astronomy · #Astrophysics #Astrophysics and Cosmic Phenomena #Atomic physics #Bulge #Cosmology #Cosmology and Gravitation Theories #Dark Matter and Cosmic Phenomena #Dark energy #Dark fluid #Dark matter #Excited state #Fermion #Galaxy #Milky Way #Particle physics #Physics #RADIUS #astro-ph #hep-ph

paper · pdf · doi:10.1103/physrevd.76.083519

published as Phys.Rev.D76:083519,2007 · 11 pages; v2 references added; v3 updated model to allow for single excitations and calculation of single excitation cross section; updated halo profiles; references added; conclusions unchanged

arxiv created 2007/05/10 · openalex publication_date 2007/10/22 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05

Abstract

We propose a dark matter candidate with an ``excited state'' 1--2 MeV above the ground state, which may be collisionally excited and deexcites by e⁺e^\ensuremath- pair emission. By converting its kinetic energy into pairs, such a particle could produce a substantial fraction of the 511 keV line observed by the International Gamma-Ray Astrophysics Laboratory/SPI in the inner Milky Way. Only a small fraction of the dark matter candidates have sufficient energy to excite, and that fraction drops sharply with galactocentric radius, naturally yielding a radial cutoff, as observed. Even if the scattering probability in the inner kpc is \ensuremath≪1% per Hubble time, enough power is available to produce the \ensuremath∼3\ifmmode×\else\texttimes\fi10⁴² pairs per second observed in the galactic bulge. We specify the parameters of a pseudo-Dirac fermion designed to explain the positron signal, and find that it annihilates chiefly to e⁺e^\ensuremath- and freezes out with the correct relic density. We discuss possible observational consequences of this model.

Citations

• A Survey of [CLC][ITAL]z[/ITAL][/CLC] ] 5.7 Quasars in the Sloan Digital Sky Survey. II. Discovery of Three Additional Quasars at [CLC][ITAL]z[/ITAL][/CLC] ] 6
• Positron annihilation spectrum from the Galactic Centre region observed by SPI/INTEGRAL
• GRBs and the 511 keV emission of the Galactic bulge
• MeV Dark Matter: Has It Been Detected?
• Dark matter with invisible light from heavy double charged leptons of almost-commutative geometry?
• Review of Particle Physics

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