A Dark Matter Superfluid

TL;DR

This paper proposes a unified framework where dark matter forms a superfluid in galaxies, explaining MOND-like behavior, while in clusters it exists in a mixed phase, aligning with cosmological observations.

Contribution

It introduces a superfluid dark matter model that unifies galactic MOND phenomena with LambdaCDM cosmology, highlighting phase transitions and potential laboratory analogues.

Findings

Dark matter forms a superfluid in galaxies, mediating MOND-like forces.

In clusters, dark matter exists in a mixed superfluid-normal phase.

Superfluid properties resemble those of cold atom systems.

Abstract

In this talk we present a novel framework that unifies the stunning success of MOND on galactic scales with the triumph of the LambdaCDM model on cosmological scales. This is achieved through the rich and well-studied physics of superfluidity. The dark matter and MOND components have a common origin, representing different phases of a single underlying substance. In galaxies, dark matter thermalizes and condenses to form a superfluid phase. The superfluid phonons couple to baryonic matter particles and mediate a MOND-like force. Our framework naturally distinguishes between galaxies (where MOND is successful) and galaxy clusters (where MOND is not): dark matter has a higher temperature in clusters, and hence is in a mixture of superfluid and normal phase. The rich and well-studied physics of superfluidity leads to a number of striking observational signatures, which we briefly discuss. Remarkably the critical temperature and equation of state of the dark matter superfluid are similar to those of known cold atom systems. Identifying a precise cold atom analogue would give important insights on the microphysical interactions underlying DM superfluidity. Tantalizingly, it might open the possibility of simulating the properties and dynamics of galaxies in laboratory experiments.