Evidence for accretion disks

Evidence for accretion disks - Evidence for accretion disks...

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Evidence for accretion disks Since most AGN models agree that the action is controlled by some kind of accretion disk around a massive black hole, it would be highly desirable to see some direct evidence of such a disk. This has so far been equivocal (at best). There are several different conceptual matters here - do such disks exist, do are they important in channeling the energetics of the nuclei, and can we see the disks directly in some way? Direct evidence of accretion disks in AGN is in short supply. Some of the approaches that have been reported include a quasi-thermal excess in the UV, polarized emission scattered off a disklike structure, two-peaked disk-like emission line profiles, and a search for the expected Lyman limit absorption due to a disk sufficient to produce the UV bump. The results indicate either disks on the wrong scale, inconclusive evidence, or no such signature as predicted. The UV excess (or
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This note was uploaded on 11/10/2011 for the course AST AST1002 taught by Professor Emilyhoward during the Fall '10 term at Broward College.

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Evidence for accretion disks - Evidence for accretion disks...

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