Galactic cold dark matter as a Bose-Einstein condensate of WISPs

TL;DR

This paper models galactic dark matter as a Bose-Einstein condensate of WISPs, deriving density profiles and constraining particle properties using galaxy data, suggesting ultra-light bosons as dark matter candidates.

Contribution

It introduces a novel BEC-based model for galactic dark matter with specific particle property constraints derived from observational data.

Findings

Dark matter particles likely have masses between 10^{-6} and 10^{-4} eV.

Lower bound for scattering length is approximately 10^{-14} fm.

Model fits well with data from spiral and LSB galaxies.

Abstract

We propose here the dark matter content of galaxies as a cold bosonic fluid composed of Weakly Interacting Slim Particles (WISPs), represented by spin-0 axion-like particles and spin-1 hidden bosons, thermalized in the Bose-Einstein condensation state and bounded by their self-gravitational potential. We analyze two zero-momentum configurations: the polar phases in which spin alignment of two neighbouring particles is anti-parallel and the ferromagnetic phases in which every particle spin is aligned in the same direction. Using the mean field approximation we derive the Gross-Pitaevskii equations for both cases, and, supposing the dark matter to be a polytropic fluid, we describe the particles density profile as Thomas-Fermi distributions characterized by the halo radii and in terms of the scattering lengths and mass of each particle. By comparing this model with data obtained from 42 spiral galaxies and 19 Low Surface Brightness (LSB) galaxies, we constrain the dark matter particle mass to the range $10^{-6}-10^{-4} eV$ and we find the lower bound for the scattering length to be of the order $10^{-14} fm$.