Normal Incidence X-Ray Telescope Power Spectra of X-Ray Emission from Solar Active Regions. II. Theory

Abstract

We use the very high resolution images of coronal active regions obtained by the Normal Incidence X-Ray Telescope to search for features of magnetohydrodynamic (MHD) fluctuations. By Fourier analyzing these images we find a broad-band, isotropic, power-law spectrum for the spatial distribution of soft X-ray inten- sities. The presence of a broad-band spectrum indicates that magnetic structures of all sizes are present, at least down to the resolution limit of the instrument, which is ~0':75. From a sample of topologically different active regions, we obtain power spectra for their X-ray intensities which falls off with increasing wavenumber as k- 3 •