Fluorescent Lyman α emission from gas near a QSO at redshift 4.28

We use integral field spectroscopy with the Gemini North Telescope to detect probable fluorescent Lyman alpha (Ly alpha) emission from gas lying close to the luminous QSO PSS 2155+1358 at redshift 4.28. The emission is most likely coming not from primordial gas, but from a multiphase, chemically enriched cloud of gas lying about 50 kpc from the QSO. It appears to be associated with a highly ionized associated absorber seen in the QSO spectrum. With the exception of this gas cloud, the environment of the QSO is remarkably free of neutral hydrogen. We also marginally detect Ly alpha emission from a foreground subdamped Ly alpha absorption-line system.