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High-Resolution Simulation on Structure Formation with Extremely Light Bosonic Dark Matter

An alternative bosonic dark matter model is examined in detail via high-resolution simulations. These bosons have particle mass of order $10^{-22}eV$ and are non-interacting. If they do exist and can account for structure formation, these bosons must be condensed into the Bose-Einstein state and described by a coherent wave function. This matter, also known as Fuzzy Dark Matter (Hu, Barkana & Gruzinov 2000),, is speculated to be able, first, to eliminate the sub-galactic halos to solve the problem of over-abundance of dwarf galaxies, and, second, to produce flat halo cores in galaxies suggested by some observations. Our simulation results show that although this extremely light bosonic dark matter indeed suppresses low-mass halos, it can, to the contrary of expectation, yield singular halo cores. The density profile of the singular halo is almost identical to the halo profile of Navarro, Frenk & White (1997). Such a profile seems to be universal, in that it can be produced via either accretion or merger.