Primordial plasma: influence of non-ideality on equilibrium radiation
The asymptotic behavior of the equilibrium radiation in Maxwellian plasma is studied for the low--frequency region. It is shown, that the equilibrium radiation can essentially deviate from the Planck law even for a weakly non-ideal plasma. The deviation from the Planck distribution is described by the transverse dielectric permittivity which takes into account both frequency and spatial dispersion. The influence of plasma non-ideality increases with the non-ideality parameter in the dielectric permittivity. The spectral energy distribution of the equilibrium radiation essentially changes in the region of observable frequencies. At asymptotically low frequencies, the equilibrium radiation begins to exhibit power behavior instead the logarithmic one. The results indicate that the spectral energy distribution of radiation could be different then the Planck one in the primordial plasma of the early Universe.