Clumpy Neutralino Dark Matter
L. Bergstrom, J. Edsjo, P. Gondolo, P. Ullio
TL;DR
This paper investigates how a clumpy Milky Way dark matter halo would impact indirect detection signals from neutralino annihilation. Using a phenomenological framework with clump fraction $f$, typical clump mass $M_{cl}$, and density contrast $\delta$, the authors show that signal enhancements in many-clump regimes scale with the product $f\delta$, enabling bounds on clumpiness from gamma-ray and antiproton data. They explore MSSM neutralino parameter space, finding that current gamma-ray and antiproton observations place robust constraints on clumpiness, while neutrino signals from the Earth and Sun are less affected. They also outline parameter regions where future gamma-ray lines, positrons, and diffuse neutrinos from halo annihilations could yield detectable signals, especially if clumpiness concentrates toward the Galactic center.
Abstract
We investigate the possibility to detect neutralino dark matter in a scenario in which the galactic dark halo is clumpy. We find that under customary assumptions on various astrophysical parameters, the antiproton and continuum gamma-ray signals from neutralino annihilation in the halo put the strongest limits on the clumpiness of a neutralino halo. We argue that indirect detection through neutrinos from the Earth and the Sun should not be much affected by clumpiness. We identify situations in parameter space where the gamma-ray line, positron and diffuse neutrino signals from annihilations in the halo may provide interesting signals in upcoming detectors.