Experimental Constraints on the Axion Dark Matter Halo Density

Most of the mass of the Milky Way galaxy is contributed by its halo, presumably in the form of non-interacting cold dark matter. The axion is a compelling cold dark matter candidate. We report results from a search which probes the local galactic halo axion density using the Sikivie RF cavity technique. Candidates over the frequency range 550$$ \(\le\) f $\le$$$ 810 MHz (2.3$$ \(\mu\)eV $\le$$$ m\(_{a}\) \(\le\) 3.4 \(\mu\)eV) were investigated. The absence of a signal suggests that KSVZ axions contribute no more than 0.45 GeV/cm\(^3\) of mass density to the local dark matter halo over this mass range.