Abstract
Abstract Low mass galaxies in the Local Group are dominated by dark matter and comprise the well studied “dwarf Spheroidal" (dSph) class, with typical masses of 109−10M⊙ and also the equally numerous “ultra faint dwarfs" (UFD), discovered recently, that are distinctly smaller and denser with masses of only 107−8M⊙. This bimodality amongst low mass galaxies contrasts with the scale free continuity expected for galaxies formed under gravity, as in the standard Cold Dark Matter (CDM) model for heavy particles. Within each dwarf class we find the core radius Rc is inversely related to velocity dispersion σ, quite the opposite of standard expectations, but indicative of dark matter in a Bose-Einstein state, where the Uncertainty Principle requires Rc × σ is fixed by Planks constant, h. The corresponding boson mass, mb = h/Rcσ, differs by one order of magnitude between the UDF and dSph classes, with 10−21.4eV and 10−20.3eV respectively. Two boson species is reinforced by parallel relations seen between the central density and radius of UDF and dSph dwarfs respectively, which both match the steep prediction, ρc ∝ Rc−4, for soliton cores in the ground state. Furthermore, soliton cores accurately fit the stellar profiles of UDF and dSph dwarfs where prominent, dense cores appear surrounded by low density halos, as predicted by our simulations. Multiple bosons may point to a String Theory interpretation for dark matter, where a discrete mass spectrum of axions is generically predicted to span many decades in mass, offering a unifying "Axiverse" interpretation for the physical "diversity" of dark matter dominated dwarf galaxies.