Earth-mass dark halos are torn into dark mini-streams by stars

Abstract

The promising neutralino dark matter particles generically condense into numerous earth-mass dark halos with smaller substructures suppressed by free streaming\cite{berezinsky}. The recent {\it Letter to Nature}\cite{moore} claims that these 0.01pc-sized dense halos emerged at redshifts 60--26 are rarely destructed inside galaxies, hence the nearest halos at about 0.1pc from Earth are bright in annihilation-powered gamma-rays, but are inaccessible to direct detections. However, most mini-halos reaching solar neighbourhood should experience strong impulses by individual stars in the Galactic disk and bulge, and have been torn into pc-long tidal streams over a Hubble time with only modest overdensity, reducing indirect annihilation signals. Sweeping across the solar system per century, mini-streams leave directional and temporal signatures for direct searches of neutralinos.

Submitted to nature, 4 pages, no figures; more robust estimations of star density in disk and bulge are made. Text is shortened to fit Nature limit