Cosmic rays in the solar system

Supervisor: Dr. Timo Laitinen

The solar system is permeated with high-energy charged particles that have been accelerated to relativistic energies at solar eruptions, and in astrophysical eruptions in our galaxy and beyond. They affect our lives in various ways – causing damage to spacecraft and humans in space and at high altitudes at Earth. The cosmic rays are one of the most significant unsolved problems that hinder human space travel to other planets.

We know that cosmic rays from the Sun, the Solar Energetic Particles (SEPs), are accelerated during solar eruptions, as we observe them with instruments onboard spacecraft typically in near-Earth space.  However, as the SEPs propagate through turbulent interplanetary space, it is very difficult to connect the SEP observations to the eruption processes: The SEPs scatter off and wander along the turbulent fields, and as a result the SEP observations give us only a smeared imprint of the original SEP acceleration processes. For this reason, it is important to understand how the interplanetary turbulence affects the SEP propagation.

We have created several models to investigate how different mechanisms affect the SEP propagation in the heliosphere. This project will use and develop these models in order to understand the SEP events observed with the new ESA and NASA solar missions Solar Orbiter (SolO) and Parker Solar Probe (PSP). SolO and PSP  have recently begun their observations of the Sun and target higher altitudes and closer distances to the Sun, and the SEP sources, thus giving us an unprecedented view of the SEPs. The project will analyse SEP and solar eruption observations from these missions, as well as a wealth of other missions such as SDO and SOHO, which can be used to characterise the solar eruptions that the SEPs are connected to.