11 papers
Principal Component Analysis of AGN Spectra
Zhaohui Shang, Beverley J. Wills
We discuss spectral principal component analysis (SPCA) and show examples of its application in analyzing AGN spectra in both small and large samples. It can be used to identify pe…
Indicators of Black Hole Mass and Eddington Accretion Ratio from QSO X-ray and UV Spectra
Beverley J. Wills, Zhaohui Shang
The evolution of luminous QSOs is linked to the evolution of massive galaxies. We know this because the relic black-holes found locally have masses dependent on the properties of t…
HST Ultraviolet and Ground-based Optical Spectropolarimetry of IRAS QSOs: Dusty Scattering in Luminous AGN
D. C. Hines, G. D. Schmidt, K. D. Gordon +4
We present UV and optical spectropolarimetry of two highly polarized IRAS-selected QSOs, IRAS 13349+2438 and the BALQSO IRAS 14026+4341. The polarization in both objects rises rapi…
X-ray Absorption in Radio-Quiet QSOs
W. N. Brandt, S. C. Gallagher, A. Laor +1
Major flows of ionized gas are thought to be present in the nuclei of most luminous QSOs, and absorption by these flows often has a significant effect upon the observed X-ray conti…
Introduction to Unified Schemes
Beverley J. Wills
The differences among apparently diverse classes of AGN are mainly the result of viewing the central engine at different orientations, because dust, which absorbs and scatters the…
The PG X-ray QSO sample: Links between the UV-X-ray Continuum and Emission Lines
Beverley J. Wills, M. S. Brotherton, A. Laor +4
The UV to soft X-rays of luminous AGNs dominate their bolometric luminosity, driven by an accretion-powered dynamo at the center. These photons ionize the surrounding gas, thereby…