Efficiency of dynamos from an autonomous generation of chiral asymmetry
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arXiv
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| Formato: | Preprint |
| Publicado: |
2024
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| _version_ | 1866929456174596096 |
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| author | Schober, Jennifer Rogachevskii, Igor Brandenburg, Axel |
| author_facet | Schober, Jennifer Rogachevskii, Igor Brandenburg, Axel |
| contents | At high energies, the dynamics of a plasma with charged fermions can be described in terms of chiral magnetohydrodynamics. Using direct numerical simulations, we demonstrate that chiral magnetic waves (CMWs) can produce a chiral asymmetry $μ_5 = μ_\mathrm{L} - μ_\mathrm{R}$ from a spatially fluctuating (inhomogeneous) chemical potential $μ= μ_\mathrm{L} + μ_\mathrm{R}$, where $μ_\mathrm{L}$ and $μ_\mathrm{R}$ are the chemical potentials of left- and right-handed electrically charged fermions, respectively. If the frequency of the CMW is less than or comparable to the characteristic growth rate of the chiral dynamo instability, the magnetic field can be amplified on small spatial scales. The growth rate of this small-scale chiral dynamo instability is determined by the spatial maximum value of $μ_5$ fluctuations. Therefore, the magnetic field amplification occurs during periods when $μ_5$ reaches temporal maxima during the CMW. If the small-scale chiral dynamo instability leads to a magnetic field strength that exceeds a critical value, which depends on the resistivity and the initial value of $μ$, magnetically dominated turbulence is produced. Turbulence gives rise to a large-scale dynamo instability, which we find to be caused by the magnetic alpha effect. Our results have consequences for the dynamics of certain high-energy plasmas, such as the early Universe. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2404_07845 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Efficiency of dynamos from an autonomous generation of chiral asymmetry Schober, Jennifer Rogachevskii, Igor Brandenburg, Axel Plasma Physics Cosmology and Nongalactic Astrophysics High Energy Physics - Phenomenology At high energies, the dynamics of a plasma with charged fermions can be described in terms of chiral magnetohydrodynamics. Using direct numerical simulations, we demonstrate that chiral magnetic waves (CMWs) can produce a chiral asymmetry $μ_5 = μ_\mathrm{L} - μ_\mathrm{R}$ from a spatially fluctuating (inhomogeneous) chemical potential $μ= μ_\mathrm{L} + μ_\mathrm{R}$, where $μ_\mathrm{L}$ and $μ_\mathrm{R}$ are the chemical potentials of left- and right-handed electrically charged fermions, respectively. If the frequency of the CMW is less than or comparable to the characteristic growth rate of the chiral dynamo instability, the magnetic field can be amplified on small spatial scales. The growth rate of this small-scale chiral dynamo instability is determined by the spatial maximum value of $μ_5$ fluctuations. Therefore, the magnetic field amplification occurs during periods when $μ_5$ reaches temporal maxima during the CMW. If the small-scale chiral dynamo instability leads to a magnetic field strength that exceeds a critical value, which depends on the resistivity and the initial value of $μ$, magnetically dominated turbulence is produced. Turbulence gives rise to a large-scale dynamo instability, which we find to be caused by the magnetic alpha effect. Our results have consequences for the dynamics of certain high-energy plasmas, such as the early Universe. |
| title | Efficiency of dynamos from an autonomous generation of chiral asymmetry |
| topic | Plasma Physics Cosmology and Nongalactic Astrophysics High Energy Physics - Phenomenology |
| url | https://arxiv.org/abs/2404.07845 |