Particle acceleration and transport from the Sun to the outer heliosphere
Pitch Angle Scattering of Solar Flare Electrons in the Inner Heliosphere
Date Submitted
2016-04-07 13:47:06
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.
Schedule
id
Monday
date time
13:30 - 15:00
14:25
Abstract
Pitch Angle Scattering of Solar Flare Electrons in the Inner Heliosphere