The warming mechanism in the clash of the Earth’s arc depends on the shock speed

The most prominent aspects of editors are summaries of recent documents of AGU magazine editors.

Fountain: Geophysical Research Letters

Arc shocks are shock waves formed upstream of astrophysical objects when they interact with a supersonic plasma flow, such as the solar wind. These clashes can heat electrons through different processes, some of which imply soft and gradual changes (Adiabatic), while others imply more chaotic (non -adiabatic) interactions. However, the relative contribution of adiabatic and non -adiabatic processes to electron heating has been a debate issue.

LALTI et al. [2024] Study data from 310 shock events observed by NASA Magnetospherical Multisalla (MMS) Space savings in the arc clash of the Earth, focusing on shock absorbers with a normal vector almost perpendicular to the direction of the magnetic field. They develop a new method to measure how much of the heating is due to non -adiabatic processes when studying patterns in electron energy distributions.

They discovered that the way in which electrons are heated are mainly controlled by the number of Alfvénic Mach, a dimensionless parameter that describes how quickly the crash moves compared to a specific speed in plasma, in a particular frame of reference (the Dehoffman-Teller framework). When this Mach number is above 30, the warming changes from being mostly adiabatic to mostly adiabatic. When non -adiabatic warming is dominant, it coincides well with a known process called stochastic shock drift acceleration.

Understanding the transition from adiabatic heating to the non -adapted in the Earth’s arch clash offers new ideas about how the particles are heated at high temperatures in our local cosmos. The findings are also directly applicable to any astrophysical shock in the same range of Mach numbers. It is likely that the observed domain of non -adiabatic heating for the high Mach numbers also remains for even higher mach numbers characteristic of some astrophysical shocks.

APPOINTMENT: LALTI, A., KHOTYAINTEV, YV and GRAHAM, DB (2024). Adiabatic and non -adiabatic electrons heating in quasi perpendicular shocks without collision. Geophysical Research Letters, 51, E2024gl112547. https://doi.org/10.1029/2024gl112547

—Marit Oieroset, former editor, Geophysical Research Letters

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