Hypothetical form of cold dark matter proposed to solve the cuspy halo problem
Fuzzy cold dark matter is a hypothetical form of cold dark matter proposed to solve the cuspy halo problem. It would consist of extremely light scalar particles with masses on the order of eV; so a Compton wavelength on the order of 1 light year. Fuzzy cold dark matter halos in dwarf galaxies would manifest wave behavior on astrophysical scales, and the cusps would be avoided through the Heisenberg uncertainty principle.[1]
The wave behavior leads to interference patterns, spherical soliton cores in dark matter halo centers,[2] and cylindrical soliton-like cores in dark matter cosmic web filaments.[3]
New research (2023) has uncovered evidence that fuzzy dark matter, specifically ultralight axions, may better fit gravitational lens data than WIMP dark matter.[6]