Effects of gravitational confinement on bosonic asymmetric dark matter in stars

TL;DR

This paper investigates how gravitational confinement within neutron stars influences the formation of Bose-Einstein condensates of bosonic asymmetric dark matter, leading to significantly improved constraints on dark matter properties.

Contribution

It introduces the effect of gravitational confinement on BEC transition temperature, strengthening bounds on dark matter-nucleon cross sections for certain mass ranges.

Findings

Gravitational confinement shifts BEC transition temperature.

Bounds on dark matter cross section are improved by an order of magnitude.

Results are relevant for dark matter particles in the 5-15 GeV mass range.

Abstract

Considering the existence of old neutron stars puts strong limits on the dark matter/nucleon cross section for bosonic asymmetric dark matter. Key to these bounds is formation of a Bose-Einstein condensate (BEC) of the asymmetric dark matter particles. We consider the effects of the host neutron star's gravitational field on the BEC transition. We find this substantially shifts the transition temperature and so strengthens the bounds on cross section. In particular, for the well-motivated mass range of ~5-15 GeV, we improve previous bounds by an order of magnitude.