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@ -29,7 +29,7 @@ Power spectral densities and time lags of 19 wavelength bands are recovered as p
\section{Introduction} \section{Introduction}
\label{sec:intro} \label{sec:intro}
Active galactic nuclei (AGN) are distant, powerfully luminous compact objects, with strongly variable spectra that have no recognized period. There is strong observational evidence that AGN influence galactic evolution through a process called AGN feedback (see \cite{2012ARA&A..50..455F} for a detailed review). Due to their immense luminosities, AGN are prime candidates for serving as standard candles to measure fundamental cosmological parameters -- well beyond the supernova horizon. The Hubble constant $H_0$ and deceleration parameter $q_0$ respectively describe the rate at which the universe is expanding and the rate at which gravity within the universe resists that expansion. \cite{1999MNRAS.302L..24C} presents a method for measuring these parameters by observing the wavelength-dependent time delays emergent from AGN systems, and this approach has been corroborated by \cite{2007MNRAS.380..669C}. Constraint of these parameters depends on properly modelling the light echo, or reverberation, effects within AGN. This work endeavors towards a better understanding of the accretion disk structure of AGN. Active galactic nuclei (AGN) are distant, powerfully luminous compact objects, with strongly variable spectra that have no recognized period. There is strong observational evidence that AGN influence galactic evolution through a process called AGN feedback (see \cite{2012ARA&A..50..455F} for a detailed review). Due to their immense luminosities, AGN are prime candidates to serve as standard candles by which to measure fundamental cosmological parameters -- well beyond the supernova horizon. The Hubble constant $H_0$ and deceleration parameter $q_0$ respectively describe the rate at which the universe is expanding and the rate at which gravity within the universe resists that expansion. \cite{1999MNRAS.302L..24C} presents a method for measuring these parameters by observing the wavelength-dependent time delays emergent from AGN systems, and this approach has been corroborated by \cite{2007MNRAS.380..669C}. Constraint of these parameters depends on properly modelling the light echo, or reverberation, effects within AGN. This work endeavors towards a better understanding of the accretion disk structure of AGN.
AGN systems are complex, with the widely-accepted picture having a super-massive black hole (SMBH) at the center, surrounded by an accretion disk, a much larger broad line region, an obscuring torus, and a relativistic matter jet. In almost all cases, astronomers are unable to resolve the configurations of these systems directly, because their angular size is far too small, so the geometry must be inferred using some other method. Reverberation mapping refers to the technique of inferring the configuration of a system by analysing the observed time lags between wavelength bands and recovering the transfer function which encodes the system geometry. It uses echoes of light to map the region surrounding the SMBH, analogous to mapping the sea floor using sonar. \cite{1999MNRAS.302L..24C} and \cite{2007MNRAS.380..669C} provide methods for constraining Hubble's constant and the deceleration parameter, with increasing certainty as the size of the dataset grows. While retaining sight of that ultimate goal, this work has a less-encompassing scope. The thermal reprocessing hypothesis describes the reprocessing of high-energy electromagnetic emission by the accretion disk; it is explained in greater detail in section \ref{sec:reverbmap}. The work executed herein attempts to test that hypothesis as one step toward greater understanding of the structure of AGN. AGN systems are complex, with the widely-accepted picture having a super-massive black hole (SMBH) at the center, surrounded by an accretion disk, a much larger broad line region, an obscuring torus, and a relativistic matter jet. In almost all cases, astronomers are unable to resolve the configurations of these systems directly, because their angular size is far too small, so the geometry must be inferred using some other method. Reverberation mapping refers to the technique of inferring the configuration of a system by analysing the observed time lags between wavelength bands and recovering the transfer function which encodes the system geometry. It uses echoes of light to map the region surrounding the SMBH, analogous to mapping the sea floor using sonar. \cite{1999MNRAS.302L..24C} and \cite{2007MNRAS.380..669C} provide methods for constraining Hubble's constant and the deceleration parameter, with increasing certainty as the size of the dataset grows. While retaining sight of that ultimate goal, this work has a less-encompassing scope. The thermal reprocessing hypothesis describes the reprocessing of high-energy electromagnetic emission by the accretion disk; it is explained in greater detail in section \ref{sec:reverbmap}. The work executed herein attempts to test that hypothesis as one step toward greater understanding of the structure of AGN.