The 130 GeV gamma-ray line and Sommerfeld enhancements

Abstract

Recently, possible indications of line spectral features in the Fermi-LAT photon spectrum towards the galactic center have been reported. If the distinct line features arise from dark matter (DM) annihilation into $\gamma X(X=\gamma ,Z^{0}or{h}^0)$, the corresponding annihilation cross-section is unnaturally large for typical loop-induced radiative processes. On the other hand, it is still too small to be responsible for the observed DM relic density. We show that the mechanism of Sommerfeld enhancement with scalar force-carrier can provide a simple solution to these puzzles. The possibly large Sommerfeld enhancement of the cross-section for s-wave DM annihilation can significantly reduce the required effective couplings between DM and charged particles in typical loop diagrams. The DM particles necessarily annihilate into scalar force-carriers through tree-level p-wave process, which can dominate the total DM annihilation cross-section at freeze out, resulting in the correct thermal relic density, but has subdominant contributions to the DM annihilation today due to velocity suppression. We perform detailed analysis on the effects of p-wave Sommerfeld enhancement on freeze out. The results show that with the constraints from the thermal relic density, the required effective couplings can be reduced by an order of magnitude.

21 pages, 16 figures; added references; version to appear in JCAP

References in corpus (11)

• Observation of an anomalous positron abundance in the cosmic radiation
• A Theory of Dark Matter
• Measurement of the Cosmic Ray e+ plus e- spectrum from 20 GeV to 1 TeV with the Fermi Large Area Telescope
• Cosmology and Astrophysics of Minimal Dark Matter
• A Tentative Gamma-Ray Line from Dark Matter Annihilation at the Fermi Large Area Telescope
• Relic densities including Sommerfeld enhancements in the MSSM
• Fermi 130 GeV gamma-ray excess and dark matter annihilation in sub-haloes and in the Galactic centre
• Two Lines or Not Two Lines? That is the Question of Gamma Ray Spectra
• Searching for the continuum spectrum photons correlated to the 130 GeV gamma-ray line
• Dipole-interacting Fermionic Dark Matter in positron, antiproton, and gamma-ray channels
• The Dark Knight Falters

Cited by in corpus (26)

• Beyond Collisionless Dark Matter: Particle Physics Dynamics for Dark Matter Halo Structure
• Teasing bits of information out of the CMB energy spectrum
• Distinguishing different scenarios of early energy release with spectral distortions of the cosmic microwave background
• Green's function of the cosmological thermalization problem
• The synergy between CMB spectral distortions and anisotropies
• The Collisional Penrose Process
• Strongly first order phase transition in the singlet fermionic dark matter model after LUX
• Non-relativistic pair annihilation of nearly mass degenerate neutralinos and charginos II. P-wave and next-to-next-to-leading order S-wave coefficients
• Sommerfeld enhancements with vector, scalar and pseudoscalar force-carriers
• Antiprotons from dark matter annihilation through light mediators and a possible excess in AMS-02 $\bar{p}/p$ data
• W-WIMP Annihilation as a Source of the Fermi Bubbles
• Light mediators in dark matter direct detections
• Long-range self-interacting dark matter in the Sun
• Simulation study of performance of the Very Large Area gamma-ray Space Telescope
• Search for gamma-ray line signals around the black hole at the galactic center with DAMPE observation
• Constraints on the Sommerfeld-enhanced dark matter annihilation from the gamma rays of subhalos and dwarf galaxies
• X-ray lines and self-interacting dark matter
• Consistent explanation for the cosmic-ray positron excess in $p$-wave Breit-Wigner enhanced dark matter annihilation
• Gamma Rays from Bino-like Dark Matter in the MSSM
• Relic Density of Asymmetric Dark Matter with Sommerfeld enhancement
• Consistent explanation for the cosmic-ray positron excess in p-wave Sommerfeld-enhanced dark matter annihilation
• Gamma-ray effects of dark forces in dark matter clumps
• Velocity-dependent self-interacting dark matter from thermal freeze-out and tests in direct detections
• Sommerfeld Enhancements for Asymmetric Dark Matter
• 130GeV gamma-ray line through axion conversion
• Dark Matter Recoupling