The galactic 511 keV line from electroweak scale WIMPs

Abstract

We consider possible mechanisms via which electroweak scale WIMPs χ^0 could provide the source of the INTEGRAL/SPI 511 keV photon flux from the galactic centre. We consider scenarios where the WIMP spectrum contains near-degeneracies, with MeV-scale splitting, and focus on three possible production mechanisms for galactic positrons: (i) collisional excitation of the WIMP to a nearby charged state, χ^0 + χ^0 -> χ^+ + χ^-, with the subsequent decay producing positrons; (ii) capture of the WIMP by nuclei in the galactic interstellar medium, χ^0 + N -> e^+ + (χ^- N); and (iii) the decay of a nearby long-lived state surviving from the Big Bang, χ^0_2 -> χ_1^0 + e^+ + e^-. We find that process (i) requires a cross-section which is significantly larger than the unitarity bound, process (ii) is allowed by unitarity, but is impractical due to terrestrial bounds on the χ-N cross-section, while process (iii) is viable and we construct a simple model realization with singlet dark matter fields interacting with the Standard Model via the Higgs sector.

16 pages, 3 figures

References in corpus (10)

• Gauge Singlet Scalars as Cold Dark Matter
• Exciting Dark Matter and the INTEGRAL/SPI 511 keV signal
• Particle physics catalysis of thermal Big Bang Nucleosynthesis
• Stau-catalyzed ${}^6$Li Production in Big-Bang Nucleosynthesis
• Primordial Lithium Abundance in Catalyzed Big Bang Nucleosynthesis
• Width of the 511 KeV Line from the Bulge of the Galaxy
• 511 KeV photons from superconducting cosmic strings
• 511 keV line and diffuse gamma rays from moduli
• MeV Right-handed Neutrinos and Dark Matter
• Difficulties for Compact Composite Object Dark Matter

Cited by in corpus (20)

• Secluded WIMP Dark Matter
• First results from DAMA/LIBRA and the combined results with DAMA/NaI
• CMB Constraints on WIMP Annihilation: Energy Absorption During the Recombination Epoch
• The DAMA/LIBRA apparatus
• Dark Matter from R^2-gravity
• Kinetic Mixing as the Origin of Light Dark Scales
• Investigating electron interacting dark matter
• Direct Detection of Multi-component Secluded WIMPs
• Nonabelian dark matter: models and constraints
• High Energy Positrons and the WMAP Haze from Exciting Dark Matter
• Breaking the Dark Force
• Sterile neutrino dark matter in $B-L$ extension of the standard model and galactic 511 keV line
• Circumscribing Late Dark Matter Decays Model Independently
• Galactic 511 keV line from MeV millicharged dark matter
• PAMELA, DAMA, INTEGRAL and Signatures of Metastable Excited WIMPs
• Diffuse MeV Gamma-rays and Galactic 511 keV Line from Decaying WIMP Dark Matter
• Diffuse cosmic gamma-rays at 1-20 MeV: A trace of the dark matter?
• Resonant scattering and recombination of pseudo-degenerate WIMPs
• On the Origin of the 511 keV Emission in the Galactic Centre
• Predictions of the causal entropic principle for environmental conditions of the universe