ON THE EFFICIENCY OF CORONAL LOOP HEATING BY RESONANT ABSORPTION

The efficiency of resonant absorption of Alfvén waves as a solar coronal loop heating mechanism is studied in the framework of linearized, compressible, resistive magnetohydrodyamics. The loops are approximated by straight cylindrical, axisymmetric plasma columns with equilibrium quantities varying only in the radial direction. The waves that are incident on the coronal loops - and excite them in this way - are modeled by a periodic external source and the stationary state of this driven system is numerically simulated by means of a very accurate code based on the finite element technique. The efficiency of the heating mechanism and the energy deposition profile in this stationary state strongly depend on the characteristics of both the external driver and the equilibrium. The numerical survey of the relevant parameter space, carried out in this paper, shows that resonant absorption is very efficient for typical coronal loops as a considerable part of the energy supplied by the external source is actually dissipated ohmically and converted into heat. Moreover, the heating rate is proportional to the square of the magnitude of the background magnetic field which is observed to be rather strong in the solar corona. Therefore, resonant absorption appears to be a viable candidate heating mechanism for solar loops.