HEATING MECHANISMS FOR INTERMITTENT LOOPS IN ACTIVE REGION CORES FROM AIA/ SDO EUV OBSERVATIONS

We investigate intensity variations and energy deposition in five coronal loops in active region cores. These were selected for their strong variability in the AIA/SDO 94 A intensity channel. We isolate the hot Fe XVIII and Fe XXI components of the 94 A and 131 A by modeling and subtracting the "warm" contributions to the emission. HM3/SDO data allow us to focus on "inter-moss" regions in the loops. The detailed evolution of the inter-moss intensity time series reveals loops that are impulsively heated in a mode compatible with a nanoflare storm, with a spike in the hot 131 A signals leading and the other five EUV emission channels following in progressive cooling order. A sharp increase in electron temperature tends to follow closely after the hot 131 A signal confirming the impulsive nature of the process. A cooler process of growing emission measure follows more slowly. The Fourier power spectra of the hot 131 A signals, when averaged over the five loops, present three scaling regimes with break frequencies near 0.1 min super(-1) and 0.7 min super(-1). The low frequency regime corresponds to 1/f noise; the intermediate indicates a persistent scaling process and the high frequencies show white noise. Very similar results are found for the energy dissipation in a 2D "hybrid" shell model of loop magneto-turbulence, based on reduced magnetohydrodynamics, that is compatible with nanoflare statistics. We suggest that such turbulent dissipation is the energy source for our loops.