Physical Sciences and Mathematics Commons^™

Insights From Unsupervised Clustering And Composite Spectral Analysis Into The Physical Properties Driving Emission And Absorption In Quasar Uv/Optical Spectra, Aycha Tammour

Electronic Thesis and Dissertation Repository

Although quasar spectra appear remarkably similar, subtle systematic differences are well- known and are linked to the physical conditions in the emitting regions. This thesis char- acterizes the properties of quasar optical and UV spectral features and reveals some of their underlying physical causes by analyzing large spectroscopic datasets from the Sloan Digital Sky Survey.

We first examine the narrow-line region using four optical emission lines with a range of ionization potentials (IPs) using a sample of 16,027 quasars with redshift z ≤ 0.75. We bin the sample using the continuum luminosity and the Hβ width to constrain the accretion …

Applying Hierarchical Clustering To Broad Absorption Line Profiles For Quasar Classification, Nathalie Chantal Marie Thibert

2016 Undergraduate Awards

The region immediately surrounding an actively accreting supermassive black hole at the centre of a massive galaxy, the accretion disk, produces an enormous amount of radiation resulting in a luminous, short-lived phenomenon called a quasar. About 20% of quasars show broad, blue-shifted absorption features in their UV spectra, indicative of an outflowing wind from the accretion disk. These winds can remove angular momentum from the accretion disk, thereby contributing to the growth of the central black hole. Understanding these winds will help us to better constrain the details of how black holes grow during the quasar phase. The structures of …