The NANOGrav 15yr Data Set: Search for Signals from New Physics

Authors

• Adeela Afzal, University of Münster
• Gabriella Agazie, University of Wisconsin-Milwaukee
• Akash Anumarlapudi, University of Wisconsin-Milwaukee
• Anne M. Archibald, Newcastle University
• Zaven Arzoumanian, NASA Goddard Space Flight Center
• Paul T. Baker, Widener University
• Bence Bécsy, Oregon State University
• Jose Juan Blanco-Pillado, Universidad del Pais Vasco
• Laura Blecha, University of Florida
• Kimberly K. Boddy, The University of Texas at Austin
• Adam Brazier, Cornell Center for Astrophysics and Planetary Science
• Paul R. Brook, University of Birmingham
• Sarah Burke-Spolaor, West Virginia University
• Rand Burnette, Oregon State University
• Robin Case, Oregon State University
• Maria Charisi, Vanderbilt University
• Shami Chatterjee, Cornell Center for Astrophysics and Planetary Science
• Katerina Chatziioannou, California Institute of Technology
• Belinda D. Cheeseboro, West Virginia University
• Siyuan Chen, Peking University
• Tyler Cohen, New Mexico Institute of Mining and Technology
• James M. Cordes, Cornell Center for Astrophysics and Planetary Science

Document Type

Article

Publication Title

Astrophysical Journal Letters

Department

Physics

ISSN

20418213

Volume

951

Issue

1

DOI

10.3847/2041-8213/acdc91

First Page

1

Last Page

56

Publication Date

6-29-2023

Abstract

The 15 yr pulsar timing data set collected by the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) shows positive evidence for the presence of a low-frequency gravitational-wave (GW) background. In this paper, we investigate potential cosmological interpretations of this signal, specifically cosmic inflation, scalar-induced GWs, first-order phase transitions, cosmic strings, and domain walls. We find that, with the exception of stable cosmic strings of field theory origin, all these models can reproduce the observed signal. When compared to the standard interpretation in terms of inspiraling supermassive black hole binaries (SMBHBs), many cosmological models seem to provide a better fit resulting in Bayes factors in the range from 10 to 100. However, these results strongly depend on modeling assumptions about the cosmic SMBHB population and, at this stage, should not be regarded as evidence for new physics. Furthermore, we identify excluded parameter regions where the predicted GW signal from cosmological sources significantly exceeds the NANOGrav signal. These parameter constraints are independent of the origin of the NANOGrav signal and illustrate how pulsar timing data provide a new way to constrain the parameter space of these models. Finally, we search for deterministic signals produced by models of ultralight dark matter (ULDM) and dark matter substructures in the Milky Way. We find no evidence for either of these signals and thus report updated constraints on these models. In the case of ULDM, these constraints outperform torsion balance and atomic clock constraints for ULDM coupled to electrons, muons, or gluons.

Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 International License.

Recommended Citation

Afzal, Adeela; Agazie, Gabriella; Anumarlapudi, Akash; Archibald, Anne M.; Arzoumanian, Zaven; Baker, Paul T.; Bécsy, Bence; Blanco-Pillado, Jose Juan; Blecha, Laura; Boddy, Kimberly K.; Brazier, Adam; Brook, Paul R.; Burke-Spolaor, Sarah; Burnette, Rand; Case, Robin; Charisi, Maria; Chatterjee, Shami; Chatziioannou, Katerina; Cheeseboro, Belinda D.; Chen, Siyuan; Cohen, Tyler; and Cordes, James M., "The NANOGrav 15yr Data Set: Search for Signals from New Physics" (2023). Pacific Faculty Work. 153.
https://scholarlycommons.pacific.edu/all-faculty/153