Tracking the origin of black holes with the stochastic gravitational wave background popcorn signal

TL;DR

This paper investigates how the statistical properties of the stochastic gravitational wave background can distinguish between primordial black holes and stellar-origin black holes, focusing on the duty cycle differences detectable by ground-based detectors.

Contribution

It introduces a method to differentiate primordial from astrophysical black holes by analyzing the duty cycle of their gravitational wave background.

Findings

Primordial black hole background has a higher duty cycle than stellar black hole background.

Differences in mass function and merger rate influence the background's statistical regime.

Potential to identify black hole origins through stochastic background analysis.

Abstract

Unresolved sources of gravitational waves (GWs) produced by the merger of a binary of black holes at cosmological distances combine into a stochastic background. Such a background is in the continuous or popcorn regime, depending on whether the GW rate is high enough so that two or more events overlap in the same frequency band. These two regimes respectively correspond to large and small values of the so-called {\it duty cycle}. We study the detection regime of the background in models of Primordial Black Holes (PBHs) and compare it to the one produced by black holes of stellar origin. Focusing on ground-based detectors, we show that the duty cycle of the PBH-origin background is larger than that of astrophysical black holes because of differences in their mass function and the merger rate. Our study opens up the possibility to learn about the primordial or astrophysical nature of black hole populations by examining the statistical properties of the stochastic background.