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   PR # 42151
   A recent ROSAT study of a complete & well defined sample of 23
   optically selected QSOs indicates that in most QSOs the X-ray
   emission is very well correlated w/ the optical emission. However,
   three of the 23 QSOs appear to form a distinct group of apparently
   "X-ray quiet" QSOs, where the X-ray flux is 10-30 times weaker than
   expected. Do the three quasars represent a population of
   intrinsically X-ray quiet QSOs? or are these just highly absorbed,
   but otherwise normal QSOs? The answer has implications for the X-ray
   prod. mechanism, for the environment in the inner parts of QSOs, and
   for AGN unification models. Some hints from the ROSAT analysis
   suggest that these objects are indeed highly absorbed quasars. ASCA
   will allow a nearly clear cut test of the true nature of X-ray quiet
   QSOs
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