Linking Solar Flares and Solar Energetic Particles through Observations and Modelling

The relation between different energetic particle populations accelerated in the solar atmosphere and detected in interplanetary space is not well-established. Observational studies during the RHESSI era demonstrated the still poorly understood existence of a connection between solar flare signatures of accelerated electrons at the Sun and the corresponding solar energetic particles (SEPs) detected at 1 AU. It is thus important to make progress towards answering the question: Under which circumstances do these two observations point to the same population of accelerated electrons? Here, we will discuss our recent studies concerned with this issue. We illustrate the potential for observations and the simultaneous modelling of the escaping and precipitating electron populations to constrain the plasma properties of the flaring region (e.g., its size, temperature, density, turbulence). We emphazize the importance of such studies for the fundamental understanding of processes that impact on energetic particle transport and acceleration in space plasmas.