Cosmological Standard Timers from Unstable Primordial Relics

TL;DR

This paper explores the concept of using unstable primordial relics, like primordial black hole bubbles, as cosmic timers to trace the Universe's evolution through their time-varying properties and mass functions.

Contribution

It introduces the novel idea of standard timers from primordial relics and demonstrates their potential using primordial black hole bubbles and Hawking radiation analysis.

Findings

Primordial black hole bubbles can act as standard timers.

Mass functions can calibrate the evolution of these timers.

The inverse problem of Hawking radiation helps analyze their properties.

Abstract

In this article we study a hypothetical possibility of tracking the evolution of our Universe by introducing a series of the so-called standard timers. Any unstable primordial relics generated in the very early Universe may serve as the standard timers, as they can evolve through the whole cosmological background until their end while their certain time-varying properties could be a possible timer by recording the amount of physical time elapsed since the very early moments. Accordingly, if one could observe these quantities at different redshifts, then a redshift-time relation of the cosmic history can be attained. To illustrate such a hypothetical possibility, we consider the primordial black hole bubbles as a concrete example and analyze the mass function inside a redshifted bubble by investigating the inverse problem of Hawking radiation. To complete the analyses theoretically, the mass distribution can serve as a calibration of the standard timers.