Search for very high energy gamma rays from WIMP annihilations near the Sun with the Milagro detector

The neutralino, the lightest stable supersymmetric particle, is a strong theoretical candidate for the missing astronomical “dark matter”. A profusion of such neutralinos can accumulate near the Sun when they lose energy upon scattering and are gravitationally captured. Pair-annihilations of those neutralinos may produce very high-energy (VHE, above 100 GeV) gamma rays. Milagro is an air shower array which uses the water Cherenkov technique to detect extensive-air showers and is capable of observing VHE gamma rays from the direction of the Sun with an angular resolution of $0.75°$. Analysis of Milagro data with an exposure to the Sun of 1165 hours presents the first attempt to detect TeV gamma rays produced by annihilating neutralinos captured by the Solar system and shows no statistically significant signal. Resulting limits that can be set on the gamma-ray flux due to near-Solar neutralino annihilations and on the neutralino cross-section are presented.