Aberration features in directional dark matter detection
  The motion of the Earth around the Sun causes an annual change in the
magnitude and direction of the arrival velocity of dark matter particles on
Earth, in a way analogous to aberration of stellar light. In directional
detectors, aberration of weakly interacting massive particles (WIMPs) modulates
the pattern of nuclear recoil directions in a way that depends on the orbital
velocity of the Earth and the local galactic distribution of WIMP velocities.
Knowing the former, WIMP aberration can give information on the latter, besides
being a curious way of confirming the revolution of the Earth and the
extraterrestrial provenance of WIMPs. While observing the full aberration
pattern requires extremely large exposures, we claim that the annual variation
of the mean recoil direction or of the event counts over specific solid angles
may be detectable with moderately large exposures. For example, integrated
counts over Galactic hemispheres separated by planes perpendicular to Earth's
orbit would modulate annually, resulting in Galactic Hemisphere Annual
Modulations (GHAM) with amplitudes larger than the usual non-directional annual
modulation.
