Generation of Alfven Waves by Magnetic Reconnection

H. Kigure

Results for 2.5-dimensional magnetohydrodynamical (MHD)
simulations are reported for the magnetic reconnection of non-perfectly
antiparallel magnetic fields. The magnetic field has a component
perpendicular
to the computational plane, that is, guide field. The angle $\theta$
between
magnetic field lines in two half regions
is a key parameter in our simulations. Alfv\'en waves
are generated at the reconnection point and propagate along the reconnected
field line. The energy fluxes of the Alfv\'en waves and slow-mode
MHD waves generated by the magnetic reconnection are measured. Each flux
shows
the similar time evolution independent of $\theta$. The percentage of the
energies (time integral of energy fluxes) carried by the Alfv\'en waves and
slow-mode waves to the released magnetic energy are calculated. The
Alfv\'en
waves carry 32.9\%, 36.1\%, and 34.4\% of the released magnetic energy
at the
maximum in the case of $\beta=0.2$, $1.0$, and $10.0$ respectively, where
$\beta$ is the plasma $\beta$ (the ratio of gas pressure to magnetic
pressure). The slow-mode waves carry 20.0\%, 26.8\%, and 62.9\% of the
energy
at the maximum. The energy carried by the Alfv\'en waves in our results is
sufficient for solar coronal heating and acceleration of high-speed
solar wind.