Quasars at 25

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Science  10 Oct 1986:
Vol. 234, Issue 4773, pp. 155-161
DOI: 10.1126/science.234.4773.155


In the quarter century since the first optical identification of a "radio star" (3C 48), astronomers have come to general agreement that the underlying quasar energy source is accretion onto a massive black hole. There is much less agreement on the detailed physics of the processes by which this energy is converted to the forms observed, but this has not prevented the objects from serving as valuable probes of the universe at distant times and places.