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http://hdl.handle.net/2142/30862 en Watson, W.D. Wallin, Bradley Karl 2012-05-18T15:50:20Z 2012-05-18T15:50:20Z 10000-01-01 1997 Calculations are performed that are relevant for understanding maser radiation emerging from gaseous disks at the nuclei of active galaxies. In at least one galaxy (NGC 4258), such maser radiation is observed and arises from a disk around a presumed massive black hole. The heating, cooling, and excitation mechanisms necessary for creating the physical conditions and pumping for the masing are investigated. The emergent spectra are first calculated for a smooth, Keplerian disk including the effects of radiative saturation. To understand the irregularities in space and frequency in the observations of NGC 4258, calculations are then performed with idealized turbulent velocities superimposed on the Keplerian velocity of the disk. These turbulent velocities are created by statistical sampling from a Kolmogorov-like distribution. In addition to rays of radiation parallel to the plane of the disk, rays inclined at a 7° angle (that indicated for NGC 4258) to the plane of the disk are considered. Within the context of this turbulent disk model, calculations for the time dependence of the low- and high-velocity masing features are performed and compared with observed variations from NGC 4258. Submitted by Elizabeth Kent (eckent2@illinois.edu) on 2012-05-18T15:50:20Z No. of bitstreams: 1 1997_wallin.pdf: 4875840 bytes, checksum: 3954d04c859d46c1873e8e9436168f99 (MD5) Made available in DSpace on 2012-05-18T15:50:20Z (GMT). No. of bitstreams: 1 1997_wallin.pdf: 4875840 bytes, checksum: 3954d04c859d46c1873e8e9436168f99 (MD5) Previous issue date: 1997 Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Elizabeth Kent (eckent2@illinois.edu) on 2012-05-18T15:50:20Z Item is restricted indefinitely. Restriction data tranferred 2014-07-01T11:33:26-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: thesis thesis U of I Only 4120436 ©1997 Bradley Karl Wallin maser radiation NGC 4258 Astrophysical maser radiation from Keplerian disks near active galactic nuclei Dissertation / Thesis text Physics Physics University of Illinois at Urbana-Champaign Dissertation Ph.D.