Possible detection of Ly alpha fluorescence from a damped Ly alpha system at redshift z similar to 2.8

We have detected Ly alpha emission from a damped Ly alpha system (DLA) that lies near the bright quasar HS1549+1919. The DLA has the same redshift as HS1549+1919 and was discovered in the spectrum of a faint QSO that lies 4900 away (380 proper kpc). The emission line's luminosity, double-peaked profile, and small spatial separation from the DLA suggest that it may be fluorescent Ly alpha emission from gas that is absorbing the nearby QSO's radiation. If this is the case, our observations show that the DLA has a size of at least 1."5 and that the QSO's luminosity 1 million years ago was similar to its luminosity today. A survey for similar systems within similar to 1' of bright QSOs would put interesting limits on the mean quasar lifetime.