In this talk I begin by reviewing how dark matter axions may form condensates, and the relation to classical field theory. I review how such condensates are spatially localized clumps, as they are organized by gravitation and self-interactions, discussing both the ground state and finite angular momentum states, which may populate the galaxy. I then discuss the exotic possibility of parametric resonance of these axion clumps into electromagnetic waves, after mergers, which may leave an astrophysical signature. I also discuss using ultra-light axions to resolve the core-cusp problem at the center of galaxies. Finally, I discuss the rate of decoherence of dark matter axions that are in non-trivial quantum states.
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Meeting ID: 940 6192 8497