Dark matter axions and caustic rings

Contents: 1. The strong CP problem 2. Dark matter axions 3. The cavity detector of galactic halo axions 4. Caustic rings in the density distribution of cold dark matter halosComment: 12 pages, Latex, one eps figure, talk at the Workshop "Beyond the Desert '97" at Castle Ringberg, Tegernsee, Germany, June 8-14, 199

The Search for Dark Matter Axions

Axions solve the Strong CP Problem and are a cold dark matter candidate. The combined constraints from accelerator searches, stellar evolution limits and cosmology suggest that the axion mass is in the range $3 \cdot 10^{-3} > m_a > 10^{-6}$ eV. The lower bound can, however, be relaxed in a number of ways. I discuss the constraint on axion models from the absence of isocurvature perturbations. Dark matter axions can be searched for on Earth by stimulating their conversion to microwave photons in an electromagnetic cavity permeated by a magnetic field. Using this technique, limits on the local halo density have been obtained by the Axion Dark Matter eXperiment.Comment: 10 pages, invited talk at the 41st Rencontre de Moriond on Electroweak Interactions and Unified Theories, La Thuile, Italy, March 11-18, 2006. Three references were adde

Dark matter axions '96

Contents: 1. The strong CP problem 2. Dark matter axions 3. The cavity detector of galactic halo axions 4. The phase space structure of cold dark matter halosComment: 12 pages, 2 figures, Latex, invited talk at the APCTP Inauguration Conference in Seoul, Korea, June 4-10, 1996 and at the Workshop on Aspects of Dark Matter in Astro- and Particle Physics in Heidelberg, Germany, Sept. 16-20, 199

Velocity peaks and caustic rings

The late infall of cold dark matter onto an isolated galaxy produces flows with definite local velocity vectors throughout the galactic halo. It also produces caustic rings, which are places in the halo where the dark matter density is very large. The self-similar model of halo formation predicts that the caustic ring radii $a_n$ follow the approximate law $a_n \simeq 1/n$. I interpret bumps in the rotation curves of NGC 3198 and of our own galaxy as due to caustic rings of dark matter. In this model of our halo the annual modulation effect in direct searches for WIMPs has the opposite sign from that predicted by the isothermal sphere model.Comment: 8 pages, 1 figure, to appear in the Proceedings of the 2d International Workshop on the Identification of Dark Matter, Buxton, England, Sept. 7-11, 199