Signals of the cosmological reionization in the radio sky through C and
  O fine structure lines
  We study the excitation of fine structure levels of C I, C II and O I by
ultraviolet (UV) photons around strong UV sources which are also ionizing
sources of the cosmological reionization at redshift of $\sim 10$. The
evolutions of ionized regions around a point source are calculated by solving
rate equations for non-equilibrium chemistry. Signals of UV photons through the
fine structure lines are considered to be stronger at locations of more
abundant chemical species of C I, C II and O I. Such environments would be
realized where strong fluxes of non-ionizing UV line photons available for the
pumping up of fine structure levels exist, and simultaneously ionizing UV
photons are effectively shielded by dense H I regions. Signals from H I regions
of moderately large densities induced by redshifted UV photons emitted at the
point sources are found to be dominantly large over those of others. We discuss
the detectability of the signals, and show that signals from idealized
environments will be possibly detected by radio observations with
next-generation arrays to come after the Atacama Large Millimeter/submillimeter
Array (ALMA).
