Dark radiation from a unified dark fluid model

TL;DR

This paper proposes a unified dark fluid model where dark matter interacts with dark radiation, explaining the evolution of dark radiation's effective number without common issues like blowup or late-time interaction problems.

Contribution

The model provides a novel unified framework for dark matter and dark radiation interactions, explaining their evolution without typical drawbacks.

Findings

Successfully explains the evolution of ΔN_eff

Avoids blowup of dark radiation density

Ensures interaction vanishes at late times

Abstract

We present a unified dark fluid model to describe the possible evolutionary behavior of $\Delta N_\mathrm{eff}$ in dark radiation. This model can be viewed as an interacting model for the dark sectors, in which dark matter interacts with dark radiation. We show that the evolution of $\Delta N_\mathrm{eff}$ can be nicely explained without some drawbacks, such as the blowup of $\Delta N_\mathrm{eff}$ and the non-vanishing interaction at the late time.