Bending Modes of the Heliosphere's Current Density Disk: Evidence and Particle Acceleration Processes

The characteristic time dependence of “high energy” electron populations originating from the heliosphere has been identified by the Alpha Magnetic Spectrometer detectors on board the International Space Station [1]. This exhibits periodicities with frequencies equal to 3, 2, and 1 of the Sun rotation frequency. The current density disk, which is an important feature of the heliosphere and corotates with the Sun, is suggested to be at the origin of the periodicities. In fact, the disk was predicted [2] to be subject to the excitation of bending modes. The presented theory proposes that the first three harmonics of these modes are responsible for the detections of the periodicities of the relevant electron populations and for the observed large-scale sector structure of the heliospheric magnetic field configuration. Small scale plasma collective modes (e.g. Ref. [3]) are considered in order to explain the high energy of the detected particle fluxes and a comparison is made to those detected close to the Sun where magnetic reconnection [4] can be a plausible candidate.

[1] S. C. Ting, MIT Physics Department Colloquium (2024)

[2] G. Bertin and B. Coppi, Ap. J. 298, 387 (1985)

[3] T. Chang and B. Coppi, Geophys. Res. Lett., 8, 1253 (1981)

[4] B. Coppi, G. Laval and R. Pellat, Phys. Rev. Lett. 16, 1207 (1966)