The presence of the Gunn-Peterson trough in quasar spectra determines the lower redshift bound for the occurrence of this process, after which the universe becomes transparent to photons.
Hu and White worked out this process's namesake damping envelope, which interpolates between small and large angular scales as a function of optical depth and the horizon size. The effect of this process on the CMB power spectrum is to suppress it by a constant factor at small angular scales while leaving the larger angular scales unchanged. The presence of the Gunn-Peterson trough in quasar spectra determines the lower redshift bound for the occurrence of this process, after which the universe becomes transparent to photons. This process, lasting from redshift of about 11 to about 6.5, commenced with the formation of the first quasars and followed the so-called Dark Ages. For 10 points, identify this process during the evolution of the universe when radiation caused the intergalactic medium to stop being neutral.
Hu and White worked out this process's namesake damping envelope, which interpolates between small and large angular scales as a function of optical depth and the horizon size.
epoch of reionization [prompt on "ionization"]