# Bochum 2015 – wissenschaftliches Programm

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# P: Fachverband Plasmaphysik

## P 10: Theory and Modelling I

### P 10.5: Vortrag

### Dienstag, 3. März 2015, 11:45–12:00, HZO 50

**Quasilinear theory of spontaneously emitted field fluctuations and the genesis of cosmological magnetic fields** — •Ulrich Kolberg and Reinhard Schlickeiser — Institut für Theoretische Physik, Lehrstuhl IV: Weltraum- und Astrophysik, Ruhr-Universität Bochum

Any fully-ionized collisionless plasma with finite random particle velocities contains electric and magnetic field fluctuations. The fluctuations can be of three different types: weakly damped, weakly propagating or aperiodic. The kinetics of these fluctuations in general unmagetized plasmas, governed by the competition of spontaneous emission, absorption and stimulated emission processes, is investigated, extending the well-known results for weakly damped fluctuations. The generalized Kirchhoff radiation law for both collective and non-collective fluctuations is derived, which in stationary plasmas provides the equilibrium energy densities of electromagnetic fluctuations by the ratio of the respective spontaneous emission coefficient and the true absorption coefficient. As an illustrative example the equilibrium energy densities of aperiodic transverse collective electric and magnetic fluctuations in an isotropic thermal electron-proton plasmas of density *n*_{e} is calculated as |δ *B*|=√(δ *B*)^{2}=2.8(*n*_{e}*m*_{e}*c*^{2})^{1/2}*g*^{1/2}β_{e}^{7/4} and
|δ *E*|=√(δ *E*)^{2}=3.2(*n*_{e}*m*_{e}*c*^{2})^{1/2}*g*^{1/3}β_{e}^{2}, where *g* and β_{e} denote the plasma parameter and the thermal electron velocity in units of the speed of light, respectively. For densities and temperatures of the reionized early intergalactic medium
|δ *B*|=6· 10^{−18}G and |δ *E*|=2· 10^{−16}G result.