Electromagnetic characteristics of the dynamics of a self-gravitating quasineutral plasma

The relativistic expressions for the electromagnetic fields, four-current, and charge density at a general hydrodynamical state of a quasineutral plasma with a vanishing four-vorticity are derived. These expressions are analyzed for the gravitational collapse of a spherically symmetric electron-proton plasma to a singularity. The asymptotic behavior of the electromagnetic effects near the center is discussed analytically in the Newtonian and the relativistic cases. Numerical and analytical results are presented for self-similar adiabatic-collapse solutions in both cases. It is found that the black hole has a typical ''charge over mass'' ratio at its apparent horizon during the relativistic collapse. This ratio is much smaller than unity, consistent with the plasma quasineutrality. Nevertheless conditions are specified under which the electron self-similar flow into the apparent horizon is determined mainly by the black hole's charge rather than by gravitation