Global ETD Search

1	Investigation of Fundamental Black Hole Properties of AGN through Optical Variability Ryle, Wesley Thomas 17 July 2008 (has links) Active galactic nuclei (AGN) are known to vary in brightness in all regions of the electromagnetic spectrum and over a wide range of timescales. Many methods have been utilized to transform this observed variability into meaningful information about the central engines of AGN. One such technique, adapted from time series analysis of galactic x-ray binary systems, has been used to detect a characteristic break timescale in the power density spectra of x-ray variability in Seyfert galaxies. This timescale, thought to be related to instabilities in the accretion disk, appears to scale with black hole mass over many orders of magnitude. This dissertation performs similar time series analyses with the optical data of eight blazars. The majority of these objects also display a characteristic break timescale. In cases where a black hole estimate is known, the timescales are in good agreement with the relationship observed for galactic x-ray binary systems and Seyfert galaxies. For objects of unknown mass, this relationship can be used to provide a mass estimate of the supermassive black hole. Comparisons are made between the structure function and power density spectrum for each object, and the implications for the connection between the accretion disk and the relativistic jet in AGN are discussed. structure function power density spectrum time series analysis blazars active galactic nuclei astronomy Astrophysics and Astronomy Physics
2	Asteroseismic inferences from red-giant stars Themeẞl, Nathalie 28 September 2018 (has links) No description available. 530 Physik (PPN621336750) asteroseismology red-giant stars data analysis eclipsing binary system open cluster solar-like oscillations stellar interior stellar evolution photometric time series of data stellar fundamental parameters binary analysis isochrone fitting stellar modelling global oscillation parameters asteroseismic scaling relations grid-based modelling Gaia distances ground-based photometry ground-based spectroscopy Kepler space mission power density spectrum ensemble study light curve analysis

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Investigation of Fundamental Black Hole Properties of AGN through Optical Variability

Asteroseismic inferences from red-giant stars