Recent Gravitational Wave Observation by Pulsar Timing Arrays and Primordial Black Holes: The Importance of Non-Gaussianities
Gabriele Franciolini, Antonio J. Iovino, Ville Vaskonen, Hardi Veermäe
Abstract
We study whether the signal seen by pulsar timing arrays (PTAs) may originate from gravitational waves (GWs) induced by large primordial perturbations. Such perturbations may be accompanied by a sizable primordial black hole (PBH) abundance. We improve existing analyses and show that PBH overproduction disfavors Gaussian scenarios for scalar-induced GWs at 2σ and single-field inflationary scenarios, accounting for non-Gaussianity, at 3σ as the explanation of the most constraining NANOGrav 15-year data. This tension can be relaxed in models where non-Gaussianities suppress the PBH abundance. On the flip side, the PTA data does not constrain the abundance of PBHs.
Topics & Concepts
PhysicsPrimordial black holeAstrophysicsGravitational wavePulsarCosmologySkyBinary black holeAbundance (ecology)AstronomyBiologyFisheryCosmology and Gravitation TheoriesPulsars and Gravitational Waves ResearchRadio Astronomy Observations and Technology