Dark Matter from quasi-de Sitter Horizons

TL;DR

This paper proposes a mechanism where dark matter particles are produced by the cosmic horizon during a quasi-de Sitter phase, with their mass range depending on the universe's equation of state and temperature at radiation domination.

Contribution

It introduces a horizon-based production mechanism for dark matter in a post-inflationary accelerated universe, linking particle mass to cosmological parameters.

Findings

Dark matter mass range from 10 keV to near Planck scale.

Production depends on the equation of state and horizon temperature.

Mechanism explains observed cosmological abundance.

Abstract

Assuming that (1) the universe underwent a post-inflationary accelerated expansion phase driven by a fluid with equation of state $P=w\rho$ and $-1<w<-1/3$, that (2) the cosmic horizon in an accelerating, quasi-de Sitter universe has a temperature inversely proportional to the proper size of the horizon, and that (3) we are static observers, we calculate the frozen-in density of a stable particle of mass $m$ produced by the cosmic horizon that does not undergo any number-changing processes in the late universe. We find that, as a function of the equation of state and the temperature when radiation domination starts and the quasi-de Sitter phase ends, the mass of the dark matter producing the observed cosmological abundance via this mechanism ranges from 10 keV up to close to the Planck scale.