Year: 2021
Type: article
Abstract: The NANOGrav collaboration has recently observed first evidence of a gravitational wave background (GWB) in pulsar timing data. Here we explore the possibility that this GWB is due to new physics, and show that the signal can be well fit also with peaked spectra like the ones expected from phase transitions (PTs) or from the dynamics of axion like particles (ALPs) in the early universe. We find that a good fit to the data is obtained for a very strong PT at temperatures around 1~MeV to 10~MeV. For the ALP explanation the best fit is obtained for a decay constant of F \approx 5\times 10^{17} F ≈ 5 × 10 17 ~GeV and an axion mass of 2\times 10^{-13} 2 × 10 − 13 ~eV. We also illustrate the ability of PTAs to constrain the parameter space of these models, and obtain limits which are already comparable to other cosmological bounds.
Source: SciPost Physics
Authors: Wolfram Ratzinger, Pedro Schwaller
Institution: Johannes Gutenberg University Mainz
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: diamond
Funder: Deutsche Forschungsgemeinschaft
OpenAlex ID: W3089179105