Enhancement of second-order gravitational waves at Q-ball decay

Abstract

The recent observation of ${}^4$He favors a large lepton asymmetry at the big bang nucleosynthesis. If Q-balls with a lepton charge decay after the electroweak phase transition, such a large lepton asymmetry can be generated without producing too large baryon asymmetry. In this scenario, Q-balls dominate the universe before the decay and induces the sharp transition from the early matter-dominated era to the radiation-dominated era. In this transition, the gravitational waves (GWs) are enhanced through a second-order effect of the scalar perturbations. We evaluate the density of the produced GWs and show that pulsar timing array observations can probe this scenario depending on the amplitude of the scalar perturbations.

16 pages, 4 figures

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Cited by in corpus (9)

• Enhancement of gravitational waves at Q-ball decay including non-linear density perturbations
• Unraveling the early universe's equation of state and primordial black hole production with PTA, BBN, and CMB observations
• Axion Poltergeist
• Using Gravitational Wave Signals to Disentangle Early Matter Dominated Epochs
• Big-Bang Nucleosynthesis on a bubble universe nucleated in Kerr-AdS${}_5$ Black Hole
• Gravitational Wave Mountains: current-carrying domain walls
• Charge distribution of the gauge-mediation type Q ball
• $\delta n$ formalism: A new formulation for the probability density of the curvature perturbation
• Bispectrum of induced gravitational waves in the poltergeist mechanism