deletions | additions       diff --git a/subsection_Background_The_physics_of__.tex b/subsection_Background_The_physics_of__.tex  index 0452108..fb2a3b1 100644  --- a/subsection_Background_The_physics_of__.tex  +++ b/subsection_Background_The_physics_of__.tex 
...
\subsection{Background} \subsection{Introduction}  The physics of accretion disks in active galactic nuclei (AGN) have been the subject of intensive recent work. While their huge energy output over a broad range of wavelengths (i.e. radio to X-ray) allows for detailed spectral characterization, their extremely small sizes are not resolved by even the best observatories\footnote{The observatories. The  \textit{Event Horizon Telescope} is the current best hope for directly imaging the accretion disk of black holes however it will only be able to observe the 2 two  nearest black holes Sgr A$^{*}$ and M87. A large resolved survey of extragalactic AGN is not possible currently or even in the near future.}. future.  Time variability analysis in different spectral bands is one of the best ways to study the structure of accretion disks as well as the mechanisms controlling the mass accretion rate crucial to understanding the physics of AGN. We propose to combine short timescale \nustar\ observations with the latest \swift\ Burst Alert Telescope (BAT) long timescale light curves \citep{Shimizu_2013} to study the time variability of a sample of AGN designed to span a wide range of black hole mass, AGN luminosity and Eddington ratio in the previously unexplored hard X-ray band. We will use a new maximum likelihood technique to construct the power spectral density functions (PSD) over a large range of timescales (years to hundreds of seconds) as well as measure the important break frequency in the PSD for the first time at high energies. The PSDs will allow us to test relationships between the observed properties of the AGN (e.g. $M_{BH}$ and $L/L_{Edd}$) and time variability \citep{Kelly_2013} and to provide important constraints on models of accretion.  We propose to combine short timescale \nustar\ observations with the latest \swift\ Burst Alert Telescope (BAT) long timescale light curves \citep{Shimizu_2013} to study the time variability of a sample of AGN designed to span a wide range of black hole mass, AGN luminosity and Eddington ratio in the previously unexplored hard X-ray band. We will use a new maximum likelihood technique to construct the power spectral density functions (PSD) over a large range of timescales (years to hundreds of seconds) as well as measure the important break frequency in the PSD for the first time at high energies. The PSDs will allow us to test relationships between the observed properties of the AGN (e.g. $M_{BH}$ and $L/L_{Edd}$) and time variability \citep{Kelly_2013} and to provide important constraints on models of accretion.