  We present observations of a population of Lya emitters (LAEs) exhibiting
fluorescent emission via the reprocessing of ionizing radiation from nearby
hyperluminous QSOs. These LAEs are part of a survey at redshifts 2.5 < z < 2.9
combining narrow-band photometric selection and spectroscopic follow-up to
characterize the emission mechanisms, physical properties, and
three-dimensional locations of the emitters with respect to their nearby
hyperluminous QSOs. These data allow us to probe the radiation field, and thus
the radiative history, of the QSOs, and we determine that most of the 8 QSOs in
our sample have been active and of comparable luminosity for a time 1 Myr < t_Q
< 20 Myr. Furthermore, we find that the ionizing QSO emission must have an
opening angle theta ~ 30 deg or larger relative to the line of sight.
