Galaxies are known to be associated with low-redshift QSOs both around the QSO itself and nearby (see the lecture on AGN hosts ). It seems too much to ask that whole groups of galaxies can share the same disease and exactly mimic distance, or that there be two populations of QSOs so contrived as to have no observable distances but be of vastly different luminosity. Oddly enough, the resolved fuzz around high-redshift QSOs recently reported by Lehnert et al (1992 ApJ 393, 68) doesn't strengthen this argument - the (1+ z ) 4 dimming in surface brightness makes normal galaxies unobservable at large redshifts, so these must be something that is peculiar by any standard. We are slowly learning that a QSO host galaxy need not look exactly like a quiescent counterpart (as in 3C 48). The broad relation between host galaxy magnitide and redshift may be construed as suggesting that the galaxies have distances related to redshift, and many are certainly galaxies containing stars as shown by direct spectroscopy. Gravitational lensing
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This note was uploaded on 11/10/2011 for the course AST AST1002 taught by Professor Emilyhoward during the Fall '10 term at Broward College.