Models of this process are constrained by an optical depth derived from the large-scale E-mode polarization power spectra of the CMB. Studying this process is the chief goal of the HERA instrument, which is a precursor to the Square Kilometer Array. One approach to studying the sources of energy for this process (15[1])relies on high-redshift analogs of Haro 11 and Tololo-1247-232, which emit photons in the LyC (“lye-C”) region. The main evidence that this process was completed around a redshift (15[1])of (*) six is that quasar (“KWAY-zar”) spectra at greater redshifts display Gunn–Peterson (-5[1])troughs. (10[1])This process began at the end of the cosmic (10[1])dark ages (10[1]-5[1])as small HII (“H-two”) regions (10[1])formed, and eventually grew to permeate the entire universe. For 10 points, name this cosmological process that occurred approximately a billion years after the Big Bang as UV light caused neutral hydrogen to lose electrons. ■END■ (10[1]0[5])