Resolving small-scale dark matter structures using multisource indirect detection

The extragalactic dark matter (DM) annihilation signal depends on the product of the clumping factor, and the velocity-weighted annihilation cross section, Ïv. This clumping factor degeneracy can be broken by comparing DM annihilation signals from multiple sources. In particular, one can constrain the minimum DM halo mass, Mmin, which depends on the mass of the DM particles and the kinetic decoupling temperature, by comparing observations of individual DM sources to the diffuse DM annihilation signal. We demonstrate this with careful semianalytic treatments of the DM contribution to the diffuse isotropic gamma-ray background (IGRB) and compare it with two recent hints of DM from the Galactic center, namely, 130 GeV DM annihilating dominantly in the channel and (10-30) GeV DM annihilating in the channels. We show that, even in the most conservative analysis, the Fermi IGRB measurement already provides interesting sensitivity. A more detailed analysis of the IGRB, with new Fermi IGRB measurements and modeling of astrophysical backgrounds, may be able to probe values of Mmin up to for the 130 GeV candidate and 10-6M for the light DM candidates. Increasing the substructure content of halos by a reasonable amount would further improve these constraints.