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Unformatted text preview: event horizon by gravitational stresses and immense friction on the incoming material.  Large central masses (10 6 to 10 9 Solar masses) have been measured in quasars using 'reverberation mapping'. Several dozen nearby large galaxies, with no sign of a quasar nucleus, have been shown to contain a similar central black hole in their nuclei, so it is thought that all large galaxies have one, but only a small fraction emit powerful radiation and so are seen as quasars. The matter accreting onto the black hole is unlikely to fall directly in, but will have some angular momentum around the black hole that will cause the matter to collect in an accretion disc . Quasars may also be ignited or re-ignited from normal galaxies when infused with a fresh source of matter. In fact, it has been theorized that a quasar could form as the Andromeda Galaxy collides with our own Milky Way galaxy in approximately 35 billion years....
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This note was uploaded on 12/15/2011 for the course AST AST1002 taught by Professor Emilyhoward during the Fall '10 term at Broward College.
- Fall '10