2001/07/03 by James Chiang, Omer Blaes
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Astrophysics and Star Formation Studies #astro-ph
paper · pdf · doi:10.1086/323077
5 pages, 2 figs, LaTeX2e, emulateapj5.sty, to appear in ApJ Letters
arxiv created 2001/07/03 · openalex publication_date 2001/08/10 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
We present an application of the thermal Comptonization/disk reprocessing model recently proposed by Zdziarski, Lubiński, & Smith. We show that the absence of strong optical variations in the presence of strong concurrent X-ray variations, similar to those found by Hubble Space Telescope ( HST )/ Rossi X-Ray Timing Explorer ( RXTE ) monitoring observations of NGC 3516, can be explained by changing the geometry of the Comptonizing plasma rather than the accretion disk itself. The total X-ray luminosity of the Comptonizing plasma must decrease as its spatial extent increases. In contrast, the disk inner radius must be roughly fixed in order not to produce optical/ultraviolet color variations stronger than observed. By including emission due to internal viscous dissipation in the disk, we can roughly match the optical and X-ray flux levels and variability amplitudes seen from NGC 3516 during the HST / RXTE campaign.