The Spectrum of Gravitational Waves from Annihilating Domain Walls
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arXiv
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| Autores principales: | , , |
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| Formato: | Preprint |
| Publicado: |
2025
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| _version_ | 1866908453393399808 |
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| author | Notari, Alessio Rompineve, Fabrizio Torrenti, Francisco |
| author_facet | Notari, Alessio Rompineve, Fabrizio Torrenti, Francisco |
| contents | Networks of cosmic domain walls can form in the early Universe as a consequence of the spontaneous breaking of discrete symmetries. We study the production of a cosmological background of gravitational waves (GWs) from such networks, when they annihilate due to a small explicit symmetry breaking term. Averaging over several 3+1-dimensional high-resolution lattice field simulations, we obtain a GW spectrum with the following characteristics: (1) a broad asymmetric peak, roughly located at frequency (at the time of emission) $f\sim 2 H_{\rm gw}$, where $H_{\rm gw}$ is the Hubble rate at the end of GW production, shortly after annihilation, (2) a doubly broken power law spectrum $\propto k^{-n}$, with initial slope $n \sim 0.5$ after the main peak and $n \sim 1.8$ at high $f$, while the low frequency region $f<f_p$ agrees with the causality behavior $\sim k^3$. Additionally, extending previous results, we find that GW production continues to be efficient until a value of the Hubble scale $H_{\text gw}$ that is roughly an order of magnitude smaller than the naive estimate $σH = ΔV$, where $σ$ is the wall tension and $ΔV$ the size of the symmetry breaking term, thereby leading to a $O(100)$ larger GW signal. We find such results to be robust when changing the shape of the scalar field potential or including a time-dependent symmetry breaking term. Our findings have important implications for GW searches, especially in light of the reported evidence for a stochastic GW background in Pulsar Timing Array data. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2504_03636 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | The Spectrum of Gravitational Waves from Annihilating Domain Walls Notari, Alessio Rompineve, Fabrizio Torrenti, Francisco Cosmology and Nongalactic Astrophysics High Energy Physics - Phenomenology Networks of cosmic domain walls can form in the early Universe as a consequence of the spontaneous breaking of discrete symmetries. We study the production of a cosmological background of gravitational waves (GWs) from such networks, when they annihilate due to a small explicit symmetry breaking term. Averaging over several 3+1-dimensional high-resolution lattice field simulations, we obtain a GW spectrum with the following characteristics: (1) a broad asymmetric peak, roughly located at frequency (at the time of emission) $f\sim 2 H_{\rm gw}$, where $H_{\rm gw}$ is the Hubble rate at the end of GW production, shortly after annihilation, (2) a doubly broken power law spectrum $\propto k^{-n}$, with initial slope $n \sim 0.5$ after the main peak and $n \sim 1.8$ at high $f$, while the low frequency region $f<f_p$ agrees with the causality behavior $\sim k^3$. Additionally, extending previous results, we find that GW production continues to be efficient until a value of the Hubble scale $H_{\text gw}$ that is roughly an order of magnitude smaller than the naive estimate $σH = ΔV$, where $σ$ is the wall tension and $ΔV$ the size of the symmetry breaking term, thereby leading to a $O(100)$ larger GW signal. We find such results to be robust when changing the shape of the scalar field potential or including a time-dependent symmetry breaking term. Our findings have important implications for GW searches, especially in light of the reported evidence for a stochastic GW background in Pulsar Timing Array data. |
| title | The Spectrum of Gravitational Waves from Annihilating Domain Walls |
| topic | Cosmology and Nongalactic Astrophysics High Energy Physics - Phenomenology |
| url | https://arxiv.org/abs/2504.03636 |