STRENGTH OF THE SPONTANEOUSLY EMITTED COLLECTIVE APERIODIC MAGNETIC FIELD FLUCTUATIONS IN THE REIONIZED EARLY INTERGALACTIC MEDIUM

Nonmagnetized, fully ionized plasmas spontaneously emit aperiodic turbulent magnetic field fluctuations. Its fluctuation intensities are dominated by the contribution from a recently discovered collective, damped mode, which modifies the earlier estimate of the total magnetic field strength in a thermal nonrelativistic electron-proton plasma to vertical bar delta B vertical bar = 24 beta(1/4)(e) (gn(e)m(e)c(2))(1/2) G, where g denotes the plasma parameter and beta(e) the thermal electron velocity in units of the speed of light, in the case of no collisional damping. Accounting for simultaneous viscous damping reduces the estimate to vertical bar delta B vertical bar(eq) = 2305g(n(e)m(e)c(2))(1/2) G, depending only on the plasma parameter g and the electron density n(e). For the unmagnetized intergalactic medium, immediately after the reionization onset the field strengths from this mechanism are about 6.8 x 10(-13) G for no collisional damping and 1.5 x 10(-16) G for viscous damping. Maximum spatial scales of 10(15) cm of the emitted aperiodic fluctuations in cosmic voids are possible.