Bose-Einstein Condensation of Dark Matter Axions
P. SikivieDepartment of Physics, University of Florida, Gainesville, Florida 32611, USAQiaoli YangDepartment of Physics, University of Florida, Gainesville, Florida 32611, USA
2009en
ABI
Abstract
We show that cold dark matter axions thermalize and form a Bose-Einstein condensate (BEC). We obtain the axion state in a homogeneous and isotropic universe, and derive the equations governing small axion perturbations. Because they form a BEC, axions differ from ordinary cold dark matter in the nonlinear regime of structure formation and upon entering the horizon. Axion BEC provides a mechanism for the production of net overall rotation in dark matter halos, and for the alignment of cosmic microwave anisotropy multipoles.
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