Tidal streams of the Sagittarius dwarf spheroidal galaxy (Sgr) may be
showering dark matter onto the solar system and contributing approx (0.3--23)%
of the local density of our Galactic Halo. If the Sagittarius galaxy contains
WIMP dark matter, the extra contribution from the stream gives rise to a
step-like feature in the energy recoil spectrum in direct dark matter
detection. For our best estimate of stream velocity (300 km/sec) and direction
(the plane containing the Sgr dwarf and its debris), the count rate is maximum
on June 28 and minimum on December 27 (for most recoil energies), and the
location of the step oscillates yearly with a phase opposite to that of the
count rate. In the CDMS experiment, for 60 GeV WIMPs, the location of the step
oscillates between 35 and 42 keV, and for the most favorable stream density,
the stream should be detectable at the 11 sigma level in four years of data
with 10 keV energy bins. Planned large detectors like XENON, CryoArray and the
directional detector DRIFT may also be able to identify the Sgr stream.Comment: 26 pages, 4 figure