  We present an analysis of galaxy and QSO absorption line pairs toward 24 QSOs
at redshifts between z~0.2 and 1 in an effort to establish the relationship
between galaxies and absorption lines in physical proximity to QSOs. We
demonstrate the existence of a galaxy proximity effect, in that galaxies in the
vicinities of QSOs do not show the same incidence and extent of gaseous
envelopes as galaxies far from QSOs. We show that the galaxy proximity effect
exists to galaxy-QSO velocity separations of ~ 3000 km/s, much larger than the
size of a typical cluster (~ 1000 km/s), i.e. it is more comparable to the
scale of the sphere of influence of QSO ionizing radiation rather than the
scale of galaxy-QSO clustering. This indicates that the QSO ionizing radiation
rather than some dynamical effect from the cluster environment is responsible
for the galaxy proximity effect. We combine previous findings that (1) many or
most Lya absorption lines arise in extended galaxy envelopes, and (2) galaxies
cluster around QSOs to show that the magnitude of the Lya forest proximity
effect is underestimated. Consequently, determinations of the UV ionizing
background intensity using the proximity effect are likely overestimated. We
use the galaxy-QSO cross-correlation function measured from our data to
estimate the magnitude of this overestimate and find that it could be as high
as a factor of 20 at z<1. This can have strong implications for models of the
origin and evolution of the ionizing background, and may indicate that QSOs
produce sufficient ionizing flux at all redshifts to account for the entire
background radiation field.
