Direct Multipoint Observations Capturing the Reformation of a Supercritical Fast Magnetosonic Shock

Abstract

Using multipoint Magnetospheric Multiscale (MMS) observations in an unusual string-of-pearls configuration, we examine in detail observations of the reformation of a fast magnetosonic shock observed on the upstream edge of a foreshock transient structure upstream of Earth's bow shock. The four MMS spacecraft were separated by several hundred km, comparable to suprathermal ion gyro-radius scales or several ion inertial lengths. At least half of the shock reformation cycle was observed, with a new shock ramp rising up out of the "foot" region of the original shock ramp. Using the multipoint observations, we convert the observed time-series data into distance along the shock normal in the shock's rest frame. That conversion allows for a unique study of the relative spatial scales of the shock's various features, including the shock's growth rate, and how they evolve during the reformation cycle. Analysis indicates that: the growth rate increases during reformation, electron-scale physics play an important role in the shock reformation, and energy conversion processes also undergo the same cyclical periodicity as reformation. Strong, thin electron-kinetic-scale current sheets and large-amplitude electrostatic and electromagnetic waves are reported. Results highlight the critical cross-scale coupling between electron-kinetic- and ion-kinetic-scale processes and details of the nature of nonstationarity, shock-front reformation at collisionless, fast magnetosonic shocks.

arXiv commentIn press and to be published in Astrophysical Journal Letters in 2021

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Cited by in corpus (6)

• Two-dimensional particle-in-cell simulation of magnetic reconnection in the downstream of a quasi-perpendicular shock
• Revealing an unexpectedly low electron injection threshold via reinforced shock acceleration
• Weibel-dominated quasi-perpendicular shock: hybrid simulations and in situ observations
• Multi-Mission Observations of Relativistic Electrons and High-Speed Jets Linked to Shock Generated Transients
• Compressive Structures in the Foreshock of Collisionless Shocks
• The Role of Gyrating Ions in Reformation of a Quasi-parallel Supercritical Shock