Properties of QSO Metal Line Absorption Systems at High Redshifts:
  Nature and Evolution of the Absorbers and New Evidence on Escape of Ionizing
  Radiation from Galaxies
  Using Voigt-profile-fitting procedures on Keck HIRES spectra of nine QSOs we
identify 1099 CIV absorber components clumped in 201 systems outside the Lyman
forest over 1.6 < z < 4.4. With associated SiIV, CII, SiII and NV where
available we investigate bulk statistical and ionization properties of the
components and systems and find no significant change in redshift for CIV and
SiIV while CII, SiII and NV change substantially. The CIV components exhibit
strong clustering but no clustering is detected for systems on scales from 150
km/s out to 50000 km/s. We conclude the clustering is due entirely to the
peculiar velocities of gas present in the circumgalactic media of galaxies.
Using specific combinations of ionic ratios we compare our observations with
model ionization predictions for absorbers exposed to the metagalactic ionizing
radiation background augmented by proximity radiation from their associated
galaxies and find the generally accepted means of radiative escape by
transparent channels from the internal star-forming sites is spectrally not
viable for our stronger absorbers. We develop an active scenario based on
runaway stars with resulting changes in the efflux of radiation that naturally
enable the needed spectral convergence and in turn provide empirical indicators
of morphological evolution in the associated galaxies. Together with a
coexisting population of relatively compact galaxies indicated by the weaker
absorbers in our sample the collective escape of radiation is sufficient to
maintain the IGM ionized over the full range 1.9 < z < 4.4.
