Particle acceleration and transport from the Sun to the outer heliosphere
Pitch Angle Scattering of Solar Flare Electrons in the Inner Heliosphere
Benjamin Alcock
Eduard Kontar, Neus Agueda
University of Glasgow
Based upon observations of hard x-ray (>10 keV) and Type-III radio emission from solar flares, the properties of the local electron population can be determined. In-situ detectors such as Wind/ 3DP can measure the electrons as they pass 1 AU, and the properties of the two populations can be compared with each other. Over the past two decades, multiple events have been found which feature delayed electron arrival at 1 AU based upon simple ballistic interplanetary transportation, and a change in the electron peak-flux spectrum compared with predictions based off of x-ray observations, or a combination of the two. We analyse several near-relativistic electron events observed via both RHESSI hard x-ray observations at the Sun and in-situ measurements from the Wind/3DP detector at 1 AU. Numerical simulations of electron transport outwards from the Sun are made, which take the electron injection time and peak-flux spectrum directly from RHESSI data, and the flux subsequently passing 1 AU is calculated. We consider the effects of adiabatic focusing and pitch angle diffusion on the particle transport, and a momentum and distance dependent form of the parallel mean free path for electrons is employed. The simulated properties of the electron population at 1 AU are then compared with Wind observations. We find that, for higher energy electrons (>40 keV), stochastic pitch angle scattering is able to explain well both the apparent delayed particle injection at the Sun, and the peak-flux spectral changes observed.


13:30 - 15:00
EX - C3 (150)