On the dark energy rest frame and the CMB

TL;DR

This paper explores the possibility that dark energy has a distinct rest frame, which could induce anisotropies in the universe and alter the CMB temperature fluctuations, especially the dipole and quadrupole moments.

Contribution

It introduces the concept of dark energy velocity as a free parameter, suggesting it can define a preferred frame and impact CMB anisotropies, a novel perspective in cosmology.

Findings

Dark energy velocity can create a preferred cosmological frame.

Dark energy motion affects CMB dipole and quadrupole.

Potential observational signatures of dark energy's rest frame.

Abstract

Dark energy is usually parametrized as a perfect fluid with negative pressure and a certain equation of state. Besides, it is supposed to interact very weakly with the rest of the components of the universe and, as a consequence, there is no reason to expect it to have the same large-scale rest frame as matter and radiation. Thus, apart from its equation of state $w$ and its energy density $\Omega_{DE}$ one should also consider its velocity as a free parameter to be determined by observations. This velocity defines a cosmological preferred frame, so the universe becomes anisotropic and, therefore, the CMB temperature fluctuations will be affected, modifying mainly the dipole and the quadrupole.