Domain Wall Model in the Galactic Bose-Einstein Condensate Halo

TL;DR

This paper explores the theoretical possibility of domain walls in galactic Bose-Einstein condensate dark matter halos and assesses their negligible impact on gravitational interactions and galaxy rotation curves.

Contribution

It introduces a model of domain walls as topological defects in Bose-Einstein condensate dark matter halos and evaluates their observational effects.

Findings

Effects of domain walls are too small to detect with current methods.

Gravitational gradient near domain walls is approximately 10^{-31} m/s^2 per meter.

Velocity correction due to domain walls is about 10^{-8} of the standard rotation velocity.

Abstract

We assume that the galactical dark matter halo, considered composed of an axionlike particles Bose-Einstein condensate \cite{pir12}, can present topological defects, namely domain walls, arising as the dark soliton solution for the Gross-Pitaevskii equation in a self-graviting potential. We investigate the influence that such substructures would have in the gravitational interactions within a galaxy. We find that, for the simple domain wall model proposed, the effects are too small to be identified, either by means of a local measurement of the gradient of the gravitational field or by analysing galaxy rotation curves. In the first case, the gradient of the gravitational field in the vicinity of the domain wall would be $10^{-31}\; (m/s^2)/m$. In the second case, the ratio of the tangential velocity correction of a star due to the presence of the domain wall to the velocity in the spherical symmetric case would be $10^{-8}$.