Looking at the NANOGrav Signal Through the Anthropic Window of Axion-Like Particles

Abstract

We explore the inflationary dynamics leading to formation of closed domain walls in course of evolution of an axion like particle (ALP) field whose Peccei-Quinn-like phase transition occurred well before inflationary epoch. Evolving after inflation, the domain walls may leave their imprint in stochastic gravitational waves background, in the frequency range accessible for the pulsar timing array measurements. We derive the characteristic strain power spectrum produced by the distribution of the closed domain walls and relate it with the recently reported NANOGrav signal excess. We found that the slope of the frequency dependence of the characteristic strain spectrum generated by the domain walls is very well centered inside the range of the slopes in the signal reported by the NANOGrav. Analyzing the inflationary dynamics of the ALP field, in consistency with the isocurvature constraint, we revealed those combinations of the parameters where the signal from the inflationary induced ALPs domain walls could saturate the amplitude of the NANOGrav excess. The evolution of big enough closed domain walls may incur in formation of wormholes with the walls escaping into baby universes. We studied the conditions, when closed walls escaped into baby universes could leave a detectable imprint in the stochastic gravitational waves background.

39 pages, 3 figures, the version accepted for publication in Physical Review D

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Cited by in corpus (35)

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• NANOGrav Signal from the End of Inflation and the LIGO Mass and Heavier Primordial Black Holes
• Probing the equation of state of the early Universe with pulsar timing arrays
• Gravitational Waves from Domain Walls in Pulsar Timing Array Datasets
• Gravitational Waves from SMBH Binaries in Light of the NANOGrav 15-Year Data
• The Detected Stochastic Gravitational Waves and Subsolar-Mass Primordial Black Holes
• Nano-Hertz gravitational waves from collapsing domain walls associated with freeze-in dark matter in light of pulsar timing array observations
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• Stability of domain wall network with initial inflationary fluctuations, and its implications for cosmic birefringence
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• Simultaneously probing the sound speed and equation of state of the early Universe with pulsar timing arrays
• Exploring the NANOGrav Signal and Planet-mass Primordial Black Holes through Higgs Inflation
• Probing the speed of scalar-induced gravitational waves with pulsar timing arrays
• Friction on ALP domain walls and gravitational waves
• Pulsar timing array observations as possible hints for nonsingular cosmology
• NANOGrav hints for first-order confinement-deconfinement phase transition in different QCD-matter scenarios
• Heavy QCD axion model in light of pulsar timing arrays
• Pulsar Timing Residual induced by Wideband Ultralight Dark Matter with Spin 0, 1, 2
• Classification of Abelian domain walls
• Enhanced curvature perturbations from spherical domain walls nucleated during inflation
• Collapsing domain walls beyond $Z_2$
• Cosmological Consequences of Domain Walls Biased by Quantum Gravity
• On mass spectra of primordial black holes
• Connecting Inflation to the NANOGrav 15-year Data Set via Massive Gravity
• Cosmological scaling of precursor domain walls
• Primordial Black Holes from Spatially Varying Cosmological Constant Induced by Field Fluctuations in Extra Dimensions
• Do we understand the internal spaces of second quantized fermion and boson fields, with gravity included? Relation with strings theories
• Interaction of domain walls with scalar particles in the early Universe
• Quark mass matrices inspired by a numerical relation
• Proceedings to the 27th Workshop "What Comes Beyond the Standard Models" Bled, July 8-17, 2024