Dark matter superfluid and DBI dark energy

TL;DR

This paper introduces a DBI scalar field model that unifies dark matter superfluid behavior and dark energy, explaining galactic dynamics and cosmic acceleration within a single framework.

Contribution

It proposes a conformally coupled DBI scalar field that explains MOND phenomena and cosmic acceleration, with a natural screening mechanism on galactic scales.

Findings

The DBI scalar field reproduces MOND-like galactic dynamics.

The screening effect explains the coincidence of MOND acceleration with the Hubble scale.

The model unifies dark matter and dark energy phenomena.

Abstract

It was shown recently that, without jeopardizing the success of the $\Lambda$ cold dark matter model on cosmic scales, the modified Newtonian dynamics (MOND) can be derived as an emergent phenomenon when axionlike dark matter particles condense into superfluid on the galactic scales. We propose in this paper a Dirac-Born-Infeld (DBI) scalar field conformally coupled to the matter components. To maintain the success of MOND phenomenon of dark matter superfluid on the galactic scales, the fifth force introduced by the DBI scalar should be screened on the galactic scales. It turns out that the screening effect naturally leads to a simple explanation for a longstanding puzzle that the MOND critical acceleration coincides with present Hubble scale. This galactic coincidence problem is solved, provided that the screened DBI scalar also plays the role of dark energy on the cosmic scales.