Galactic halo models and particle dark-matter detection
Rates for detection of weakly interacting massive-particle (WIMP) dark matter are usually carried out assuming the Milky Way halo is an isothermal sphere. However, it is possible that our halo is not precisely spherical; it may have some bulk rotation; and the radial profile may differ from that of an isothermal sphere. In this paper, we calculate detection rates in observationally consistent alternative halo models that produce the same halo contributions to the local and asymptotic rotation speeds to investigate the effects of the theoretical uncertainty of the WIMP spatial and velocity distribution. We use self-consistent models to take into account the effects of various mass distributions on the local velocity distribution. The local halo density may be increased up to a factor of 2 by flattening or by an alternative radial profile (which may also decrease the density slightly). However, changes in the WIMP velocity distribution in these models produce only negligible changes in the WIMP detection rate. Reasonable bulk rotations lead to only an O(10%) effect on event rates. We also show how the nuclear recoil spectrum in a direct-detection experiment could provide information on the shape and rotation of the halo.
Additional Information© 1998 The American Physical Society Received 14 October 1997 We thank M. Weil for useful discussions. M.K. was supported by the D.O.E grant number DEFG02-92-ER 40699, NASA NAG5-3091, and the Alfred P. Sloan Foundation. A.K. was supported by the Columbia Rabi Scholars Program which is funded in full by the Kann Rasmussen Foundation.
Published - KAMprd98b.pdf