Popcorn in the sky: Identifying primordial black holes in the gravitational-wave background

TL;DR

This paper proposes using the duty cycle of the gravitational-wave background to identify primordial black holes, offering a new method to distinguish them from other sources in upcoming GW observations.

Contribution

It introduces a novel approach to differentiate PBH signals in the GWB by analyzing the duty cycle, considering realistic PBH populations and their contributions.

Findings

Duty cycle varies with frequency, duration, and amplitude of signals.

Distinct duty cycle signatures can differentiate PBHs from other GW sources.

Analysis tools for duty cycle extraction are proposed for future GW data.

Abstract

Primordial black holes (PBHs) are possible sources of a gravitational-wave background (GWB), detectable with the next observing runs of LIGO--Virgo--KAGRA. In case of a detection, it will be crucial to distinguish the possible sources of this GWB. One under-explored possibility is to exploit the duty cycle that quantifies the number of sources present in the time domain signal, which can be very different depending on the nature and population of the sources. We compute the duty cycle for a realistic population of PBH binaries, isolating the shot-noise, popcorn and continuous contributions to the GWB. We identify the dependence of the duty cycle on the signal frequency, duration and amplitude as a crucial metric for distinguishing PBHs from other sources in the GWB and constraining PBH models. Our work motivates the development of specific analysis tools to extract these observables, in order to unlock new cosmological insights with upcoming GW data.