On the Threshold of the Reionization Epoch
On the Threshold of the Reionization Epoch
Discovery of the cosmic reionization epoch would represent a significant milestone in cosmology. We present Keck spectroscopy of the quasar SDSS 1044-0125, at z = 5.73. The spectrum shows a dramatic increase in the optical depth at observed wavelengths λ ≳ 7550 Å, corresponding to zabs ≳ 5.2. Only a …