  We use a wide-field (0.9 square degree) X-ray sample with optical and GALEX
ultraviolet observations to measure the contribution of Active Galactic Nuclei
(AGNs) to the ionizing flux as a function of redshift. Our analysis shows that
the AGN contribution to the metagalactic ionizing background peaks around z=2.
The measured values of the ionizing background from the AGNs are lower than
previous estimates and confirm that ionization from AGNs is insufficient to
maintain the observed ionization of the intergalactic medium (IGM) at z>3. We
show that only sources with broad lines in their optical spectra have
detectable ionizing flux and that the ionizing flux seen in an AGN is not
correlated with its X-ray color. We also use the GALEX observations of the
GOODS-N region to place a 2-sigma upper limit of 0.008 on the average
ionization fraction fnu(700 A)/fnu(1500 A) for 626 UV selected galaxies in the
redshift range z=0.9-1.4. We then use this limit to estimate an upper bound to
the galaxy contribution in the redshift range z=0-5. If the z~1.15 ionization
fraction is appropriate for higher redshift galaxies, then contributions from
the galaxy population are also too low to account for the IGM ionization at the
highest redshifts (z>4).
