Resolving Small-Scale Dark Matter Structures Using Multi-Source Indirect Detection

The extragalactic dark matter (DM) annihilation signal depends on the product of the clumping factor, $\langle \delta^{2} \rangle $, and the velocity-weighted annihilation cross section, $\sigma v$. It is important to determine the clumping factor as it depends on the minimum DM halo mass, $M_{\rm min}$, or equivalently the kinetic decoupling temperature of DM. In this work, we demonstrate how to break the ``clumping factor--$\sigma v$'' degeneracy by comparing the Isotropic Gamma Ray Background with tentative DM signals from the Galactic Center. We obtain interesting limits on $M_{\rm min}$ and $\sigma v$. Potential improvements in near future are discussed, which will have significant implications for the tentative DM signals.