NANOGrav spectral index γ=3 from melting domain walls

0581915 - FZÚ 2024 RIV US eng J - Článek v odborném periodiku
Babichev, E. - Gorbunov, D. - Ramazanov, Sabir - Samanta, Rome - Vikman, Alexander
NANOGrav spectral index γ=3 from melting domain walls.
Physical Review D. Roč. 108, č. 12 (2023), č. článku 123529. ISSN 2470-0010. E-ISSN 2470-0029
Grant CEP: GA MŠMT EF15_003/0000437; GA MŠMT(CZ) EF20_079/0017754; GA ČR(CZ) GA20-28525S
Grant ostatní: OP VVV - CoGraDS(XE) CZ.02.1.01/0.0/0.0/15_003/0000437; OP VVV - MSCA-IF IV FZU(XE) CZ.02.2.69/0.0/0.0/20_079/0017754
Institucionální podpora: RVO:68378271
Klíčová slova: domain walls * gravitational waves * cosmology of theories beyond the SM * NANOGrav
Obor OECD: Particles and field physics
Impakt faktor: 5, rok: 2022
Způsob publikování: Open access

We discuss cosmic domain walls described by a tension red-shifting with the expansion of the Universe. These melting domain walls emit gravitational waves with the low-frequency spectral shape $Omega_{gw}propto f^{2}$ corresponding to the spectral index $gamma=3$ favoured by the recent NANOGrav 15 yrs data. We discuss a concrete high-energy physics scenario leading to such a melting domain wall network in the early Universe. This scenario involves a feebly coupled scalar field, which can serve as a promising dark matter candidate. We identify parameters of the model matching the gravitational wave characteristics observed in the NANOGrav data. The dark matter mass is pushed to the ultra-light range below $10^{-11}-10^{-12}, ext{eV}$ which is accessible through planned observations thanks to the effects of superradiance of rotating black holes.
Trvalý link: https://hdl.handle.net/11104/0350066