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Concerning "Have all the quasars shrunk out of sight? There are none in
what are usually considered as nearby galaxies."
Quasars are thought to be galaxies in which there is a great deal of matter
falling into the black hole at the center. This infalling matter gets very
hot through collisions and radiates. Eventually the central region of the
galaxy gets depopulated of matter (the black hole is "starved") and there
is little further radiation. So one expects very early galaxies to be
intrinsically very bright, which is the situation with quasars, which have
very large redshifts interpreted as their being very far away and their
light having been emitted very long ago. The black hole at the center of
our own mature Milky Way galaxy is mostly starving, having long ago eaten
what was available.
Bruce
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