Magnetic Reconnection in the Corona as a Source of Switchbacks in the Solar Wind

Abstract

<p>The observations from the Parker Solar Probe during the first<br>perihelion revealed large numbers of local reversals in the radial<br>component of the magnetic field with associated velocity spikes. Since<br>the spacecraft was magnetically connected to a coronal hole during the<br>closest approach to the sun, one possible source of these spikes is<br>magnetic reconnection between the open field lines in the coronal hole<br>and an adjacent region of closed flux. Reconnection in a low beta<br>environment characteristic of the corona is expected to be bursty<br>rather than steady and is therefore capable of producing large numbers<br>of magnetic flux ropes with local reversals of the radial magnetic<br>field that can propagate outward large radial distances from the<br>sun. Flux ropes with a strong guide field produce signatures<br>consistent with the PSP observations. We have carried out simulations<br>of "interchange" reconnection in the corona and have explored the<br>local structure of flux ropes embedded within the expanding solar<br>wind. We have first established that traditional interchange<br>reconnection cannot produce the switchbacks since bent field lines<br>generated in the corona quickly straighten. The simulations have been<br>extended to the regime dominated by the production of multiple flux<br>ropes and we have established that flux ropes are injected into the<br>local solar wind. Local simulations of reconnection are also being<br>carried out to explore the structure of flux ropes embedded in the<br>solar wind for comparison with observations. Evidence is presented<br>that flux rope merging may be ongoing and might lead to the high<br>aspect ratio of the switchback structures measured in the solar wind.</p>