Mode Converting Alfv\'{e}n Waves from Magnetic Reconnection Enhancing the Energy Source for the Aurora Borealis

Previous studies have concluded that the Hall magnetic field structures generated during magnetic reconnection are carried away by kinetic Alfv\'{e}n waves (KAW) for distances $\sim 10R_e$. However, from our study of Hall field profiles obtained from domain $200d_i \times 30d_i$, we observe that the large scale structure is carried by waves which are super-Alfv\'{e}nic ($\sim 2V_a$ ) near the X-line where they are generated, but as they travel into the exhaust for $\sim 5R_e$ their propagation velocity decreases and become Shear Alfv\'{e}nic ( $\sim 1V_a$ ). Owing to the dispersive nature of KAW as they propagate their wavenumber, $k_{\bot}$, decreases, corresponding to a mode conversion into Shear-Alfv\'{e}n waves(SAW). This mode conversion, away from the X-line becomes important as it eliminates the energy attenuation of 99\% due to Landau damping, expected when KAWs propagate towards Earth without conversion. The SAWs permit a substantial transfer of Poynting flux to the auroral regions, enhanced by a factor of $10^3$ above previous estimates. This may lead to particle acceleration and help account for auroral brightening at locations magnetically conjugate to spacecraft observations.