Three problems of superfluid dark matter and their solution

TL;DR

This paper identifies tensions in superfluid dark matter models related to phonon roles and proposes a split-field model to resolve these issues, improving stability and revisiting galaxy core estimates.

Contribution

It introduces a novel two-field model for superfluid dark matter that separates phonon roles, addressing stability and tension problems in previous models.

Findings

Split-field model resolves phonon role tensions.

Enhanced stability of superfluid dark matter.

Revised estimates for galaxy superfluid core sizes.

Abstract

In superfluid dark matter (SFDM), the phonon field plays a double role: It carries the superfluid's energy density and it mediates the MOND-like phonon force. We show that these two roles are in tension with each other on galactic scales: A MOND-like phonon force is in tension with a superfluid in equilibrium and with a significant superfluid energy density. To avoid these tensions, we propose a model where the two roles are split between two different fields. This also allows us to solve a stability problem in a more elegant way than standard SFDM. We argue that the standard estimates for the size of a galaxy's superfluid core need to be revisited.