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Indirect WIMP detection

The Sun can potentially serve as an enormous WIMP detector. WIMPs streaming through the galactic halo would be gravitationally focused into the Sun, where they would be captured through collisions with atoms in the Sun's center [49]. Neutralinos are their own anti-particles; thus, the neutralinos in the Sun would annihilate each other. When neutralinos annihilate, they will produce high energy neutrinos that are potentially detectable in terrestrial experiments [59]. These few GeV neutrinos are much more energetic than the MeV solar neutrinos produced through solar nucleosynthesis. There is also the possibility of detecting WIMPs in the halo through their annihilation into protons and anti-protons, into electrons and positrons and into 's. The predicted rates for these processes are unfortunately rather low [21].

There have been several experiments that have looked for WIMP annihilations in the Sun. Currently, there are limits from the Kamionkande, Frejus, and MACRO experiments. In the coming years, we can look forward to more sensitive searches by the DUMAND, AMANDA and NESTOR experiments. While these searches are worthwhile, Kamionkowski et al. [38] have argued that direct experimental searches may be a more effective technique than searches for neutrinos from annihilations of SUSY relics in the Sun. However, for the rarer models with predominantly spin interactions, the converse is most likely true They conclude that for most of parameter space, 1 kg of direct detector is equivalent to 10 -10 m of indirect detector.

Dave Spergel
Wed Mar 6 14:02:15 EST 1996