paper

Ultra-Light Axion Dark Matter and its impacts on dark halo structure in -body simulation

arXiv:1611.00892 · doi:10.3847/1538-4357/aaa485

Abstract

The Ultra-Light Axion (ULA) is a dark matter candidate with mass eV and de Broglie wavelength of order kpc. Such an axion, also called the Fuzzy Dark Matter (FDM), thermalizes via the gravitational force and forms a Bose-Einstein condensate. Recent studies suggested that the quantum pressure from the FDM can significantly affect the structure formation in small scales, thus alleviating the so-called "small-scale crisis". In this paper, we develop a new technique to discretize the quantum pressure and illustrate the interactions among FDM particles in the -body simulation, which accurately simulates the formation of the dark-matter halo and its inner structure in the region outside the softening length. In a self-gravitationally-bound virialized halo, we find a constant density, solitonic core, which is consistent with the theoretical prediction. The existence of the solitonic core reveals the non-linear effect of quantum pressure and impacts the structure formation in the FDM model.

17 pages, 9 figures, Accepted by ApJ, there are minor changes in the published version, main content is the same

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