Connecting remote and in situ observations of shock-accelerated electrons associated with a coronal mass ejection

Energetic particle populations are ubiquitous throughout the Universe and often found to be accelerated by astrophysical shocks. One of the most prominent sources for energetic particles in our solar system are huge eruptions of magnetized plasma from the Sun called coronal mass ejections (CMEs), which usually drive shocks that accelerate charged particles up to relativistic energies. Accelerated electrons can be observed remotely as low-frequency radio bursts or in situ at spacecraft. However, it is currently unknown where electrons accelerated in the early phases of such eruptions propagate and when they escape the solar atmosphere to eventually reach spacecraft. Here, we present a new study that uses a three-dimensional representation of radio emission locations in relation to the overlying coronal magnetic field, shock wave propagation, magneto-hydrodynamic (MHD) models of the solar corona, and radio imaging observations from ground-based observatories. These solar observations are also combined with in situ electron data at spacecraft.  Our results indicate that if the in situ electrons are shock-accelerated, their most likely origin is at or near the acceleration site of electrons beams producing herringbone radio bursts. This is the only region during the early evolution of the CME where there is clear evidence of electron shock acceleration and intersection of the CME shock with open field lines that can connect to the observing spacecraft.