GEM: Particle Acceleration by Foreshock Transients

Shocks accelerate particles to relativistic speeds throughout the universe – in astrophysical processes and more locally in the region of space near the Earth. It is a mystery how shocks can accelerate particles to energies higher than their own shock potential energy reserve. This project will investigate irregularities in plasma flows ahead of shocks moving into the magnetosphere, studying plasma bubbles and hot flow anomalies.

The results of this project have direct applications in space weather models; it thus addresses one of the goals set out in the National Space Weather Action Plan. The project will also help understand shock acceleration throughout the universe. Three early career researchers and a graduate student will receive support.

The key objectives are (i) to determine the role of upstream electron energization on space weather phenomena that result from inward penetration of energetic particles; and (ii) to provide new insights in the classic pre-acceleration need for Fermi type shock acceleration processes. For the first time high quality and resolution THEMIS and MMS data from the foreshock region are available.

THEMIS provides data on large scale magnetic structures along with high-frequency magnetic fluctuations and superthermal particles ( >25 keV), while MMS is capable of resolving small scale (10-100 km) high time resolution (30 -150 ms) providing microscale and electron dynamics quantities. The observations will be supplemented by Cluster and DMSP which monitor the energetic particle flux in the cusp and from all sky imagers and NSF-funded SuperDARN data providing signatures of accelerating particles.

Combining these observations is a challenging task. The proposal utilizes a well-tested 3D global hybrid simulation code to organize the data and achieve the desired results.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.