Condensation of Galactic Cold Dark Matter

TL;DR

This paper models galactic dark matter halos as Bose-Einstein condensates, showing that quantum pressure can produce finite-density cores and predicting ultra-light particle masses around 10^-24 eV.

Contribution

It introduces a quantum-pressure-inclusive model for dark matter halos, addressing the cusp problem and estimating ultra-light dark matter particle mass.

Findings

Quantum pressure yields finite-density cores in halos.

Predicted dark matter particle mass around 10^-24 eV.

Density perturbation equations derived for the condensate model.

Abstract

We consider the steady-state regime describing the density profile of a dark matter halo, if dark matter is treated as a Bose-Einstein condensate. We first solve the fluid equation for "canonical" cold dark matter, obtaining a class of density profiles which includes the Navarro-Frenk-White profile, and which diverge at the halo core. We then solve numerically the equation obtained when an additional "quantum pressure" term is included in the computation of the density profile. The solution to this latter case is finite at the halo core, possibly avoiding the "cuspy halo problem" present in some cold dark matter theories. Within the model proposed, we predict the mass of the cold dark matter particle to be of the order of M_chi c2 = 10^-24 eV, which is of the same order of magnitude as that predicted in ultra-light scalar cold dark matter models. Finally, we derive the differential equation describing perturbations in the density and the pressure of the dark matter fluid.