Greg Dobler edited CAR Generation.tex  almost 11 years ago

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\subsection{CAR Generation}  \label{sec:car}  The optical light curve of quasars are generated by fluctuations in the brightness of the accretion disk with structure in the time series on the order of days [REFS]. Since these fluctuations are coherent, the implication is that the size of the accretion disk is roughly $R_{\rm src} \sim 10^{16}$ cm. cm (which will be important for the microlensing calculation in \S \ref{sec:microlensing}). These fluctuations have been shown to be well described by a Continuous Auto Regressive (CAR) process. First described by [REFS], the CAR process is a damped random walk and is equivalent to a Gaussian Process in which the covariance between two points on the light curve decreases asa function of their temporal separation. Using data from the MACHO survey [REF], [REF] fit a CAR process to {\bf (GGD: how many???)}     Using data from the MACHO survey  \begin{equation}  X(t) = e^{-t/\tau} X(0) + b\tau(1-e^{-t/\tau}) + \sigma\int_{0}^{t} e^{-(t-s)/\tau} dB(s)