Probing the Epoch of Reionization with the Lyman Alpha Forest at z~4-5
  The inhomogeneous cosmological reionization process leaves tangible imprints
in the intergalactic medium down to z=4-5. The Lyman-alpha forest flux power
spectrum provides a potentially powerful probe of the epoch of reionization.
With the existing SDSS I/II quasar sample we show that two cosmological
reionization scenarios, one completing reionization at z=6 and the other at
z=9, can be distinguished at ~7 sigma level by utilizing Lyman alpha forest
absorption spectra at z=4.5+-0.5, in the absence of other physical processes
that may also affect the Lyman alpha flux power spectrum. The redshift range
z=4-5 may provide the best window, because there is still enough transmitted
flux and quasars to measure precise statistics of the flux fluctuations, and
the IGM still retains a significant amount of memory of reionization.
