Quasar - event horizon by gravitational stresses and...

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Quasar Some quasars display changes in luminosity which are rapid in the optical range and even more rapid in the X-rays. Because these changes occur very rapidly they define an upper limit on the volume of a quasar; quasars are not much larger than the Solar System . [4] This implies an astonishingly high energy density . [5] The mechanism of brightness changes probably involves relativistic beaming of jets pointed nearly directly toward us. The highest redshift quasar known (as of June 2011) is ULAS_J1120+0641 , with a redshift of 7.085, which corresponds to a proper distance of approximately 29 billion light-years from Earth. Quasars are believed to be powered by accretion of material into supermassive black holes in the nuclei of distant galaxies, making these luminous versions of the general class of objects known as active galaxies . Since light cannot escape the super massive black holes that are at the centre of quasars, the escaping energy is actually generated outside the
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Unformatted text preview: event horizon by gravitational stresses and immense friction on the incoming material. [6] 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.

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