Detectability of a subdominant density component of cold dark matter

Here we examine the detectability of collisionless dark matter candidates that may constitute not all but only a subdominant component of galactic cold dark matter. We show that current axion searches are not suited for a subdominant component, while direct WIMP searches would not be severely affected by the reduced density. In fact, the direct detection rates of neutralinos stay almost constant even if neutralinos constitute 1% of the halo dark matter. Only for lower densities do the rates decrease with density. Even neutralinos accounting for only 10 of the local dark halo density are within proposed future discovery limits. We comment also on indirect WIMP searches. Claims for the need of collisional cold dark matter [1] as the main form of dark matter in the Universe have led us to consider the observability of collisionless cold dark matter (CCDM) when it is merely a subdominant component of the cold dark matter (CDM). Namely, if the previously favored CDM candidates, such as axions or Weakly Interacting Massive Particles (WIMPs), constitute only a fraction, say 1% or less, of the local dark matter density, would these particles still be observable in the current and proposed direct and indirect