Axion-like Universal Gravitational Wave Interpretation of Pulsar Timing Array Data

Abstract

Formation of cosmological solitons is generically accompanied by production of gravitational waves (GWs), with a universal GW background expected at frequency scales below that of non-linear dynamics. Beginning with a general phenomenological description of GWs associated with soliton formation, we demonstrate that universal GW background from axion-like particle (ALP) solitonic oscillons provides a viable interpretation to the recent NANOGrav 15 year pulsar timing array data, which does not suffer from the overproduction of primordial black holes. We show that pulsar timing array data displays preference for models where formed solitons do not strongly interact or cluster. Coincidence observations with Nancy Roman telescope will allow to discriminate between distinct scenarios of cosmological solitons.

9 pages, 2 figures; v2: figure updated, expanded discussion on observations, conclusion unchanged. Matches publication

Cited by in corpus (4)

• Simultaneously probing the sound speed and equation of state of the early Universe with pulsar timing arrays
• Realisation of the ultra-slow roll phase in Galileon inflation and PBH overproduction
• Large fluctuations and Primordial Black Holes
• Obviating PBH overproduction for SIGWs generated by Pulsar Timing Arrays in loop corrected EFT of bounce