Multi-Mission Observations of Relativistic Electrons and High-Speed Jets Linked to Shock Generated Transients

TL;DR

This study uses multi-mission data to show how shock-generated transients like HFAs accelerate electrons to relativistic energies and form high-speed jets, revealing complex shock physics and particle acceleration mechanisms.

Contribution

It demonstrates the transmission and confinement of energetic electrons through HFAs and the formation of high-speed jets at HFA edges using multi-mission observations.

Findings

Electrons are accelerated to relativistic energies within HFAs.

High-speed jets form at the edges of HFAs with increased dynamic pressure.

Quasi-parallel shocks effectively accelerate particles over larger regions.

Abstract

Shock-generated transients, such as hot flow anomalies (HFAs), upstream of planetary bow shocks, play a critical role in electron acceleration. Using multi-mission data from NASA's Magnetospheric Multiscale (MMS) and ESA's Cluster missions, we demonstrate the transmission of HFAs through Earth's quasi-parallel bow shock, associated with acceleration of electrons up to relativistic energies. Energetic electrons, initially accelerated upstream, are shown to remain broadly confined within the transmitted transient structures downstream, where betatron acceleration further boosts their energy due to elevated compression levels. Additionally, high-speed jets form at the compressive edges of HFAs, exhibiting a significant increase in dynamic pressure and potentially contributing to driving further localized compression. Our findings emphasize the efficiency of quasi-parallel shocks in driving particle acceleration far beyond the immediate shock transition region, expanding the acceleration region to a larger spatial domain. Finally, this study underscores the importance of multi-scale observational approach in understanding the convoluted processes behind collisionless shock physics and their broader implications.