Growth of Structure in Multi-species Wave Dark Matter

Abstract: We explore the growth of structure in multi-species wave (and particle) dark matter. We derive the evolution of the power spectrum of total density contrasts for an arbitrary number of component species, density fractions, and initial field power spectra. We also derive cross-spectra for density correlations across or within individual species. Our framework includes cold and warm wave dark matter, which can give rise to significant intrinsic Poisson-like density fluctuations along with scale-dependent evolution connected to the free-streaming and Jeans scales. Such dark matter components could be globally or locally misaligned scalar fields as well as multi-component fields with spin $>0$. The framework also includes cold and warm particle dark matter in the appropriate limits.