  Power spectra of Large Magellanic Cloud (LMC) emission at 24, 70 and 160
microns observed with the Spitzer Space Telescope have a two-component
power-law structure with a shallow slope of -1.6 at low wavenumber, k, and a
steep slope of -2.9 at high k. The break occurs at 1/k ~ 100-200 pc, which is
interpreted as the line-of-sight thickness of the LMC disk. The slopes are
slightly steeper for longer wavelengths, suggesting the cooler dust emission is
smoother than the hot emission. The power spectrum covers ~ 3.5 orders of
magnitude and the break in the slope is in the middle of this range on a
logarithmic scale. Large-scale driving from galactic and extragalactic
processes, including disk self-gravity, spiral waves and bars, presumably cause
the low-k structure in what is effectively a two-dimensional geometry.
Small-scale driving from stellar processes and shocks cause the high-k
structure in a 3D geometry. This transition in dimensionality corresponds to
the observed change in power spectrum slope. A companion paper models the
observed power-law with a self-gravitating hydrodynamics simulation of a galaxy
like the LMC.
