Gravitational Waves from Primordial Black Holes formed by Null Energy Condition Violation during Inflation

TL;DR

This paper explores how a temporary violation of the null energy condition during inflation can generate primordial black holes and a complex gravitational wave spectrum, offering new ways to test early universe physics with future GW observations.

Contribution

It extends previous models by calculating gravitational wave signals from PBH formation, ringdown, and mergers, revealing a multi-component GW spectrum linked to NEC violation.

Findings

Multi-component GW spectrum from PBHs includes primordial, scalar-induced, ringdown, and merger signals.

Correlated GW signatures across frequencies can constrain NEC violation during inflation.

Future GW observations can test the proposed NEC violation scenario.

Abstract

A transient violation of the null energy condition (NEC) during inflation provides a novel mechanism for producing primordial black holes (PBHs) and stochastic gravitational wave (GW) backgrounds. In this work, we extend previous studies by computing the GW contributions from both the ringdown phase of PBH formation and subsequent binary mergers. Our results show that this scenario produces a rich, multi-component GW spectrum consisting of primordial GWs, scalar-induced GWs, and GW emissions from PBH ringdown and binary mergers. We demonstrate that these correlated signatures across different frequency bands provide a novel and powerful avenue to probe or constrain NEC violation during inflation through future multi-band GW observations.