Archive for May 22, 2018

Is Dark Matter a Superfluid?

Posted in The Universe and Stuff with tags , , , , , , on May 22, 2018 by telescoper

In between marking exams and project reports I’ve been doing a little bit of reading in preparation for a talk that I’m due to give next week, which prompted me to share this talk by Justin Khoury of the University of Pennsylvania, which is about framework that unifies the claimed success of Modified Newtonian Dynamics (MOND) on galactic scales with the that of the standard ΛCDM model on cosmological scales. This is achieved through the 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. This 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 observational signatures, discussed in the talk.

The idea that dark matter might be in the form of a superfluid is not new (see e.g. this paper) but there has been a recent surge of interest driven largely by Khoury and collaborators. If you want to find out more, can find a review paper about this model here.