Toward a Reconnection Model for Solar Flare Statistics
Abstract
A model to account for observed solar flare statistics in terms of a superposition of independent random flaring elements (assumed to be sites of magnetic reconnection in the coronal magnetic field and hence termed ``separators'') is described. A separator of length l is assumed to flare as a Poisson process in time, with a rate ν(l) inversely proportional to the Alfvén transit time for the structure. It is shown that a relationship E~lκ between the mean energy of events E at a separator and the separator length implies a relationship E~τκ between individual waiting times τ and energies E of events at the separator. The most plausible κ=2 model is found to be compatible with simple pictures for magnetohydrodynamic energy storage prior to magnetic reconnection in a current sheet with anomalous (turbulent) resistivity. Formal inversion of the observed flare frequency-energy distribution is shown to imply a distribution P(l)~l-1 of the separator lengths in active regions. A simulation confirms the basic results of the model. It is also demonstrated that a model comprising time-dependent separator numbers N=N(t) can reproduce an observed power-law tail in the flare waiting-time distribution, for large waiting times.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- September 2003
- DOI:
- 10.1086/377254
- Bibcode:
- 2003ApJ...595..458W
- Keywords:
-
- Magnetohydrodynamics: MHD;
- Sun: Activity;
- Sun: Corona;
- Sun: Flares;
- Sun: Magnetic Fields