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Q:What is ADAF (Advection Dominated Accretion Flows)?A: An advection dominated accretion flow is one
in which the infalling (or accreting) matter falls into a black
hole without radiating away much of its energy, less than one
percent. This can happen if the density of the infalling matter
is low, so the particles make few collisions or their way beyond
the event horizon. If the matter is falling onto a neutron star
instead, or is spiralling slowly in a thick disk toward a black
hole, it can radiate away ten to a hundred times more energy
than in the advection case. Astronomers study the radiation
pattern to deduce what kind of accretion flow they are
observing, and whether a black hole or neutron star is
present.See the following figures: http://cfa-www.harvard.edu/blackhole/fig1.html http://cfa-www.harvard.edu/blackhole/xrayn.html and J. Lasota, "Unmasking Black Holes" Scientific American, May 99 |
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Revised: August 02, 2005
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