Observations of Non-thermal Velocity and Comparison with Alfv\'en Wave Turbulence Model in Solar Active Regions
Abstract
We present a study of spectral line width measurements from the Extreme Ultraviolet Imaging Spectrometer (EIS) on Hinode. We used spectral line profiles of Fe xvi 262.984 , Fe xiv 264.787 , Fe xiv 270.519 , Fe xiv 274.203 , and Fe xv 284.160 , and studied 11 active regions. Previous studies of spectral line widths have shown that in hot loops in the cores of active regions, the observed non-thermal velocities are smaller than predicted from models of reconnection jets in the corona or shock heating associated with Alfv\'en waves. The observed line widths are also inconsistent with models of chromospheric evaporation due to coronal nanoflares. We show that recent advances in higher resolution Alfv\'en wave turbulence modeling enables us to obtain non-thermal velocities similar to those measured in active regions. The observed non-thermal velocities for the 11 active regions in our study are in the range of 17-30 km ~ s-1, consistent with the spectral line non-thermal widths predicted from our model of 16 interacting flux tubes, which are in the range of ~15-37 km ~ s-1.
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