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Dissertation
Quasar diversity from the optical, UV, X-ray, and time domain
Doctor of Philosophy (Ph.D.), Drexel University
Sep 2021
DOI:
https://doi.org/10.17918/00000894
Abstract
We use both multi-epoch spectroscopy and multi-wavelength data to develop our understanding of black hole accretion physics. We use the multi-epoch quasar spectra to determine how accurately single-epoch spectroscopy can locate quasars in emission-line parameter space to inform investigations where time-resolved spectroscopy is not available. We explore the improvements in the calculation of emission-line measurements that arise from using non-parametric information from many lines, utilizing reconstructions based on an independent component analysis applied to data from the Sloan Digital Sky Survey Reverberation Mapping project. We further examine multi-wavelength (particularly UV/X-ray) properties of 1378 quasars in order to link correlations in observed parameters to theoretical models of the physical mechanisms dominating quasars as a function of mass and accretion rate. The clarity of these correlations is improved when 1) similarly using reconstructions based on an independent component analysis, and 2) removing quasars expected to be intrinsically absorbed based on their spectral slopes in the X-ray and optical and between the X-ray and optical. Multi-epoch spectroscopy reveals that single-epoch results do not significantly change where quasars are located in CIV parameter space and do not have a significant impact on investigations of the global Baldwin Effect. Quasars with emission line properties indicative of higher L/LEdd are less variable, consistent with models with enhanced accretion disk density. In addition to using the traditional CIV parameter space measures of CIV EQW and blueshift, we define a "CIV ll distance" along a best-fit polynomial curve that incorporates information from both CIV parameters. The CIV ll distance may be a better indicator of L/LEdd than the CIV EQW or blueshift alone as those relationships are known to break down at the extrema. However, there is only a weak correlation with the X-ray spectral index, which is also expected to be a robust indicator of L/LEdd. We find no X-ray or optical trends in the direction perpendicular to the CIV distance that could be used to reveal differences in accretion disk, wind, or corona structure that could be widening the CIV EQW-blueshift distribution. A different parameter (such as metallicity) not traced by these data must come into play.
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Details
- Title
- Quasar diversity from the optical, UV, X-ray, and time domain
- Creators
- Angelica B. Rivera
- Contributors
- Gordon T. Richards (Advisor)
- Awarding Institution
- Drexel University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- xi, 93 pages
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- College of Arts and Sciences; Physics; Drexel University
- Other Identifier
- 991015684243904721