Synchrotron radiation from instabilities in the early universe

Abstract

The post recombination era before the start of re-ionization is observationally quite challenging. Due to the lownumber density of charge carriers in the plasma during this period, electromagnetic signatures are difficult to predict. We discuss a scenario where charge separation instabilities are generated in a magnetized plasma in this era. Such instabilities will generate strong electric fields in the plasma. Any charged particle passing through these regions of electromagnetic fields, will emit synchrotron radiation. We calculate the strength of the electric field generated for a given magnetic field and obtain the synchrotron radiation spectrum for charged electrons moving through such electromagnetic fields.We find that the critical frequency of the emitted radiation is of the order of 1010 MHz.