@article{af12da4dd7b24e92b76f45135f0f599d,

title = "Nano-Hz Gravitational-Wave Signature from Axion Dark Matter",

abstract = "We calculate the accurate spectrum of the stochastic gravitational-wave background from U(1) gauge fields produced by axion dark matter. The explosive production of gauge fields soon invalidates the applicability of the linear analysis and one needs nonlinear schemes. We make use of numerical lattice simulations to properly follow the nonlinear dynamics such as backreaction and rescattering which gives important contributions to the emission of gravitational waves. It turns out that the axion with the decay constant f1016 GeV and the mass m10-14 eV which gives the correct dark matter abundance predicts the circularly polarized gravitational-wave signature detectable by SKA. We also show that the resulting gravitational-wave spectrum has a potential to explain NANOGrav 12.5 yr data.",

author = "Naoya Kitajima and Jiro Soda and Yuko Urakawa",

note = "Funding Information: We thank Wolfram Ratzinger and Pedro Schwaller for helpful comments. N. K. is supported by JSPS KAKENHI Grants No. JP18H01243, No. JP19K14708, and No. 20H01894. N. K. and Y. U. are supported by JSPS KAKENHI Grant No. JP19H01894. J. S. was in part supported by JSPS KAKENHI Grants No. JP17H02894 and No. JP20H01902. Y. U. is also supported by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)—Project No. 315477589—TRR 211. The authors thank Yukawa Institute for Theoretical Physics at Kyoto University. Discussions during the YITP workshop YITP-T-19-02 on “Resonant instabilities in cosmology” were useful to complete this work. Publisher Copyright: {\textcopyright} 2021 American Physical Society. ",

year = "2021",

month = mar,

day = "26",

doi = "10.1103/PhysRevLett.126.121301",

language = "English",

volume = "126",

journal = "Physical Review Letters",

issn = "0031-9007",

publisher = "American Physical Society",

number = "12",

}