Solar-Mass Primordial Black Holes Explain NANOGrav Hint of Gravitational Waves

TL;DR

This paper proposes that the recent NANOGrav gravitational wave signal could be explained by second-order GWs from the formation of solar-mass primordial black holes, suggesting a new astrophysical origin for the observed background.

Contribution

It introduces the novel idea that primordial black hole formation could account for the NANOGrav gravitational wave hint, linking PBH formation to stochastic GW background detection.

Findings

Primordial black hole formation can produce second-order gravitational waves.

The proposed model explains the NANOGrav signal as originating from PBHs.

Future GW observations can test this hypothesis.

Abstract

The NANOGrav collaboration for the pulsar timing array (PTA) observation recently announced evidence of an isotropic stochastic process, which may be the first detection of the stochastic gravitational-wave (GW) background. We discuss the possibility that the signal is caused by the second-order GWs associated with the formation of solar-mass primordial black holes (PBHs). This possibility can be tested by future interferometer-type GW observations targeting the stochastic GWs from merger events of solar-mass PBHs as well as by updates of PTA observations.