  We study the fluctuations of standard thin accretion disks by linear analysis
of the time-dependent energy equation together with the vertical hydrostatic
equilibrium and the equation of state. We show that some of the simulation
results in Hirose et al. (2009b), such as the time delay, the relationship of
power spectra, and the correlation between magnetic energy and radiation
energy, can be well understood by our analytic results.
