Revisiting evolution of domain walls and their gravitational radiation with CosmoLattice

Abstract

Employing the publicly available CosmoLattice code, we conduct numerical simulations of a domain wall network and the resulting gravitational waves (GWs) in a radiation-dominated Universe in the $Z_2$-symmetric scalar field model. In particular, the domain wall evolution is investigated in detail both before and after reaching the scaling regime, using the combination of numerical and theoretical methods. We demonstrate that the total area of closed walls is negligible compared to that of a single long wall stretching throughout the simulation box. Therefore, the closed walls are unlikely to have a significant impact on the overall network evolution. This is in contrast with the case of cosmic strings, where formation of loops is crucial for maintaining the system in the scaling regime. To obtain the GW spectrum, we develop a technique that separates physical effects from numerical artefacts arising due to finite box size and non-zero lattice spacing. Our results on the GW spectrum agree well with Refs. [29, 30], which use different codes. Notably, we observe a peak at the Hubble scale, an exponential falloff at scales shorter than the wall width, and a plateau/bump at intermediate scales. We also study sensitivity of obtained results on the choice of initial conditions. We find that different types of initial conditions lead to qualitatively similar domain wall evolution in the scaling regime, but with important variations translating into different intensities of GWs.

32 pages, 9 figures; typos fixed, gravitational wave spectral indices are slightly updated; matches version accepted in JCAP

References in corpus (23)

• The NANOGrav 15-year Data Set: Evidence for a Gravitational-Wave Background
• Laser Interferometer Space Antenna
• Search for an isotropic gravitational-wave background with the Parkes Pulsar Timing Array
• Searching for the nano-Hertz stochastic gravitational wave background with the Chinese Pulsar Timing Array Data Release I
• The second data release from the European Pulsar Timing Array III. Search for gravitational wave signals
• The NANOGrav 15-year Data Set: Search for Signals from New Physics
• The NANOGrav 15-year Data Set: Constraints on Supermassive Black Hole Binaries from the Gravitational Wave Background
• Axion cosmology with long-lived domain walls
• CosmoLattice
• Causal gravitational waves as a probe of free streaming particles and the expansion of the Universe
• NANOGrav spectral index $\gamma =3$ from melting domain walls
• Gravitational shine of dark domain walls
• Beyond freeze-in: Dark Matter via inverse phase transition and gravitational wave signal
• Friction on ALP domain walls and gravitational waves
• Stability of domain walls in models with asymmetric potentials
• Primordial Black Holes from Axion Domain Wall Collapse
• Stretching and Kibble scaling regimes for Hubble-damped defect networks
• Domain wall annihilation -- a QFT perspective
• Stability of domain walls with inflationary fluctuations under potential bias, and gravitational wave signatures
• Present and future of CosmoLattice
• Dynamics of Long-lived Axion Domain Walls and Its Cosmological Implications
• Cosmic Simulations of Axion String-Wall Networks: Probing Dark Matter and Gravitational Waves for Discovery
• Solving the domain wall problem with first-order phase transition

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• Caustic formation in DBI models: Wave propagation on planar domain walls
• Gravitational Wave Mountains: current-carrying domain walls