Axion string source modeling
Year: 2024
Type: article
Abstract: In this paper, we investigate the effect of the string radius of curvature R Gaussian on the massive and massless scalar radiation emitted from collisions of traveling waves propagating along an axion (global cosmic) string. We construct initial conditions for two colliding Gaussians and perform parameter scans over their amplitude A and standard deviation σ d . We show that these collisions emit isotropic bursts of massless radiation and that the energy emitted via this channel obeys a power law ∼ ∝ A γ , where the coefficient γ depends on the regime of A / δ and δ is the string width. Massive radiation is exponentially suppressed ∼ ∝ e − ζ R Gaussian in the quasilinear regime σ d ≫ δ and exhibits power-law decay ∼ ∝ R Gaussian − γ ′ in the nonlinear regime σ d ≲ 2 δ , with different ζ and γ ′ in different regimes of R Gaussian . In this nonlinear regime, massive particle radiation can comprise up to 50% of the total energy emitted. Drawing on a known parallel between axion radiation from global strings and gravitational radiation from Abelian-Higgs strings, this suggests that massive particle radiation may become significant with respect to the massless (gravitational) channel for such nonlinear burst signals. For all configurations studied, we obtain a spectral index q ≳ 1 for the axion radiation, where q → 1 as A increases; i.e., a higher proportion of radiation is emitted in high-frequency modes. Published by the American Physical Society 2024
Institution: University of Cambridge
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: hybrid
Funders: Intel Corporation, Department for Business, Energy and Industrial Strategy, UK Government, University of Cambridge, European Cooperation in Science and Technology, Engineering and Physical Sciences Research Council, Science and Technology Facilities Council, Fundação para a Ciência e a Tecnologia, Homerton College, University of Cambridge
Awards: G1525616127, G1736745720, G1771230537, G1827715697, G1854719645, G2073976794, REVEALING THE STRUCTURE OF THE UNIVERSE: GRAVITATIONAL WAVES, COSMOLOGY AND EXOPLANETS, G3047881983, G3149743720, G3563244976, G3641108176, G3680780005, G3682537941, G3911511115, Revealing the Structure of the Universe: From Extreme Gravity to Exoplanets, G4022262583, DiRAC 2.5 Operations 2017-2020, G5660267321, G5997058474, G6181174915, G6537386148, G6802598382, G6955735330, G7108246583, Sondas astrofísicas da física fundamental, G7447190122, G7573294876, G7629755209, G7702914472, G7937591081, G8150249736, G8695159654, G878803593
OpenAlex ID: W4401514148