Substructure Boosts to Dark Matter Annihilation from Sommerfeld Enhancement

Abstract

The recently introduced Sommerfeld enhancement of the dark matter annihilation cross section has important implications for the detection of dark matter annihilation in subhalos in the Galactic halo. In addition to the boost to the dark matter annihilation cross section from the high densities of these subhalos with respect to the main halo, an additional boost caused by the Sommerfeld enhancement results from the fact that they are kinematically colder than the Galactic halo. If we further believe the generic prediction of CDM that in each subhalo there is an abundance of substructure which is approximately self-similar to that of the Galactic halo, then I show that additional boosts coming from the density enhancements of these small substructures and their small velocity dispersions enhance the dark matter annihilation cross section even further. I find that very large boost factors ($10^5$ to $10^9$) are obtained in a large class of models. The implications of these boost factors for the detection of dark matter annihilation from dwarf Spheroidal galaxies in the Galactic halo are such that, generically, they outshine the background gamma-ray flux and are detectable by the Fermi Gamma-ray Space Telescope.

PRD in press

References in corpus (16)

• Observation of an anomalous positron abundance in the cosmic radiation
• A Theory of Dark Matter
• A new measurement of the antiproton-to-proton flux ratio up to 100 GeV in the cosmic radiation
• The redshift dependence of the structure of massive LCDM halos
• The Luminosity Function of the Milky Way Satellites
• Cosmic-ray positron fraction measurement from 1 to 30 GeV with AMS-01
• Gamma-ray and radio tests of the e+e- excess from DM annihilations
• Minimal Dark Matter predictions for galactic positrons, anti-protons, photons
• Evidence Of Dark Matter Annihilations In The WMAP Haze
• Pre-launch estimates for GLAST sensitivity to Dark Matter annihilation signals
• TeV gamma-rays and the largest masses and annihilation cross sections of neutralino dark matter
• Gamma-ray continuum emission from the inner Galactic region as observed with INTEGRAL/SPI
• Dark Matter Annihilation in Substructures Revised
• Upper limit for gamma-ray emission above 140 GeV from the dwarf spheroidal galaxy Draco
• Circular velocity profiles of dark matter haloes
• Dark Matter annihilation in Draco: new considerations of the expected gamma flux

Cited by in corpus (5)

• CMB Constraints on WIMP Annihilation: Energy Absorption During the Recombination Epoch
• Dark matter interpretation of recent electron and positron data
• Inverse Compton constraints on the Dark Matter e+e- excesses
• Nonabelian dark matter: models and constraints
• Mirage in the Sky: Non-thermal Dark Matter, Gravitino Problem, and Cosmic Ray Anomalies