We present observations of a population of Ly \alpha 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 \lesssim t _ { \textrm { \scriptsize { Q } } } \lesssim 20 Myr .
Furthermore , we find that the ionizing QSO emission must have an opening angle \theta \sim 30 \arcdeg or larger relative to the line of sight .