Substantial equilibrium charge separation in a self-gravitating plasma, with application to galaxies

Abstract

It is generally thought that equilibrium self-gravitating condensations of plasma must be electrically quasineutral. While this is true in the case of an atomic plasma, there is a realizable type of plasma in which it is not true. If the massive component of a two-component plasma consists of charged macroscopic solid grains for which the charge-to-mass ratio is of order √G , then self-gravitation and thermalization lead to substantial equilibrium charge separation. Within a thermalized gravitational condensation of this plasma, the scale height of the oppositely charged low-mass component is much larger than that of the grains. Consequently, the large-scale charge-to-mass ratio is also of order √G . There is evidence that an understanding of such condensations may be relevant to the understanding of galaxies.