Temporal and Physical Relationships Between CME Acceleration and Flare Energy Release

The physical relationship between CMEs and flares is re-examined from both observational and theoretical points of view, utilizing the new SECCHI as well as LASCO observations. For the theoretical model, we use the erupting flux-rope model that has been shown to replicate observed CME trajectories. Mathematically, this model starts with an equilibrium flux rope and drives it with a specified function dΦp(t)/dt increasing the poloidal flux Φp. Physically, the injected flux may be of coronal or subphotospheric origin. The function dΦp/dt is parameterized by the ramp-up and ramp-down time scales, the peak duration, and the peak value. For each event, we obtain the "best fit" solution to fit the entire trajectory (out to HI1 if available) by adjusting these parameters. It is found that the duration of required poloidal flux injection is closely correlated with the duration of associated GOES X-ray profile. This correlation holds for short- duration as well as long-duration flares. This suggests that the poloidal flux injection has a physical connection to observed CME dynamics and flare energy release. Injection of poloidal flux produces an electromotive force (EMF) around the flux rope that has the same functional form and duration as dΦp/dt. The EMF is sufficient to accelerate particles to several tens of keV and higher in one collisional mean free path. In the model, the main acceleration phase is governed by the intrinsic time scale (Alfvenic time in the flux rope) and the geometry (footpoint separation distance) of the flux rope, insensitive to the form of dΦp/dt. The duration of the flux injection, however, is sensitive to the long-time propagation properties of the CME in HI1 field of view. The model results are compared with published results of arcade models. Work supported by ONR and NASA