Name: Paul Gilbert
How are quasars powered and what causes their intense luminosities? Is the
quasar actually a small galaxy in itself or a forming star?
Quasars are now thought to be galaxy-like rather than star-like, although
the name comes "quasi-stellar object." When first discovered in 1965 (by a
graduate student!) they were thought to be nearby stellar objects because of
their luminosity and size (they appeared as point sources like stars), but
they had extremely high red shifts which usually indicates extreme distance.
If they are far away, then their energy output is ENORMOUS. We really do
not know what their power source could be except to say that it probably
involves one or more massive black holes. But that is really just a guess
because we do not know of any physical mechanisms that can produce so much
energy from a something the size of a galaxy for a long period of time. One
idea is that quasars are galaxies in a very early stage of development.
Their extreme distance makes them extremely old. If you believe in a
continuous morphology of galaxies and similar objects, then "Seyfert
galaxies" may be what quasars evolve into.
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Update: June 2012