Orientation and discontinuity analyses of near-Sun magnetic field switchbacks

Abstract:

Magnetic switchbacks are Alfvenic structures characterized as intervals of large, intermittent reversals in the radial component of magnetic field. Switchbacks comprise of magnetic spikes preceded/succeeded by quiet, pristine solar wind. Here, we investigate the orientations of switchback transition regions which separate switchback spikes from quiet solar wind, using fields and plasma suites aboard the Parker Solar Probe. First, the minimum variance analysis is applied on transition region magnetic signatures. It is determined that the leading (trailing) edge of switchbacks are oriented toward (away from) the heliospheric current sheet. Next, discontinuity analyses are performed on the different switchback regions. Our results indicate that switchbacks are rotational (tangential) discontinuities in 84% (16%) of events. In agreement with Ulysses’ observations of high-latitude solar coronal holes, it is discovered that the rotational and tangential switchbacks are different in their relative change in plasma beta, defined as the ratio of local thermal and magnetic pressures, across the transition region. Finally, it is concluded that the small relative change in plasma beta and the negligible magnetic curvature across switchback transition regions may inhibit local magnetic reconnection.