Unified Superfluid Dark Sector

TL;DR

This paper introduces a unified dark sector model where dark matter superfluid dynamics naturally produce late-time cosmic acceleration, eliminating the need for dark energy and matching observed expansion and structure growth.

Contribution

It proposes a novel two-state dark matter superfluid model that explains cosmic acceleration without dark energy, extending the superfluid dark matter framework.

Findings

The model predicts a different growth rate of cosmic structures compared to $\\Lambda$CDM.

It reproduces the observed late-time acceleration of the universe.

The expansion history aligns with current cosmological observations.

Abstract

In this talk I present a new model of a unified dark sector, where late-time cosmic acceleration emerges from the dark matter (DM) superfluid framework. We will start by reviewing the dark matter superfluid model and show how it describes the dynamics of DM in large and small scales. Then we will show that if the superfluid consists of a mixture of two distinguishable states with a small energy gap, such as the ground state and an excited state of DM, interacting through a contact interaction a new dynamics of late-time accelerated expansion emerges in this system, without the need of dark energy, coming from a universe containing only this two-state DM superfluid. I will show the expansion history and growth of linear perturbations, and show that the difference in the predicted growth rate in comparison to $\Lambda$CDM is significant at late times.