  We use morphological information of X-ray selected AGN hosts to set limits on
the fraction of the accretion density of the Universe at z~1 that is not likely
to be associated with major mergers. Deep X-ray observations are combined with
high resolution optical data from the Hubble Space Telescope in the AEGIS,
GOODS North and GOODS South fields to explore the morphological breakdown of
X-ray sources in the redshift interval 0.5<z<1.3. The sample is split into
disks, early-type bulge dominated galaxies, peculiar systems and point-sources
in which the nuclear source outshines the host galaxy. The X-ray luminosity
function and luminosity density of AGN at z~1 are then calculated as a function
of morphological type. We find that disk-dominated hosts contribute 30\pm9 per
cent to the total AGN space density and 23\pm6 per cent to the luminosity
density at z~1. We argue that AGN in disk galaxies are most likely fueled not
by major merger events but by minor interactions or internal instabilities. We
find evidence that these mechanisms may be more efficient in producing luminous
AGN (L_X>1e44 erg/s) compared to predictions for the stochastic fueling of
massive black holes in disk galaxies.
