Spontaneous Generation of Alfven Waves by Bursty Interchange Magnetic Reconnection in the Solar Corona

Abstract

Alfven waves contribute significantly to the solar coronal heating, the solar wind acceleration, as well as Alfv\'enic turbulence formation. As a universal process, magnetic reconnection has long been credited as a potentially crucial source of Alfven waves, but how magnetic reconnection trigger Alfven waves remains elusive. Here, with simulations of three-dimensional bursty interchange magnetic reconnection in the solar corona, for the first time, we find that Alfven waves are spontaneously excited in the reconnection sheet and propagate bi-directionally even along the unreconnected magnetic fields. The enhanced total pressure inherently carried by flux ropes gives kicks to the magnetic fields, and the nearly same propagation speed of the flux ropes and the kicks makes the kicks growing into the observed Alfven waves, which have large amplitudes and high frequencies, carrying substantial energy for heating the quiet corona and accelerating the solar wind. Our findings demonstrate that Alfven waves are natural products of three-dimensional intermittent magnetic reconnection, bringing its fundamental significance for energy release, transport, and conversion occurring in the plasma system.