Testing the Neupert Effect With Combined Fokker-Planck and Hydrodynamic Simulations
Abstract
The Neupert effect in solar flares is an empirical temporal correlation between the microwave or hard X-ray (HXR) flux and the time derivative of the soft X-ray (SXR) flux. Such a correlation is expected from a simple energy argument and is considered as evidence of chromospheric evaporation. However, a quantitative statistical correlation and physical connection between these emissions have not been established, and in some flares the Neupert effect is not observed. In this study we apply a state-of-the-art combined Fokker-Planck (Petrosian et al. 2001) and hydrodynamic (Mariska et al. 1989) code to model the atmospheric response to collisional heating by accelerated electrons. This code treats acceleration and transport of particles and hydrodynamics of plasma in a self-consistent manner (Liu 2006). It also evaluates various energy contents and thermal SXR and nonthermal HXR bremsstrahlung emissions. We confirm the existence of a temporal and statistical correlation between the SXR derivative and the HXR flux. In addition, we find a statistically more significant and physically more natural correlation between the SXR derivative and the thermal energy variation rate. The simulation results will be presented and implications for the energy release and particle acceleration processes in solar flares will be discussed.
- Publication:
-
37th COSPAR Scientific Assembly
- Pub Date:
- 2008
- Bibcode:
- 2008cosp...37.1804L