Positron Signal from the Early Universe

TL;DR

This paper proposes that early universe bursts could produce positrons leading to detectable X-ray signals today, offering a new way to observe and confirm explosive events in the universe's infancy.

Contribution

It introduces the idea that early universe bursts can produce observable positron annihilation signals, linking high-redshift events to present-day X-ray observations.

Findings

Observable X-ray photons originate at red-shift z≈200-300.

Positrons are absent in standard early universe models at these red-shifts.

Detection of these X-rays would support the existence of early universe bursts.

Abstract

Bursts from the very early universe may lead to a detectable signal via the production of positrons, whose annihilation gives an observable X-ray signal. Using the absorption parameters for the annihilation photons of 511 keV, it is found that observable photons would originate at a red-shift around $z\approx$ 200-300, resulting in soft X-rays of energy $\sim$ 2-3 keV at present. Positrons are expected to be absent at these times or red-shifts in the standard picture of the early universe. Detection of the X-rays would thus provide dramatic support for the hypothesis of the bursts, explosive events at very early times. We urge the search for such a signal.