太阳物理研究组知识库

Laboratory experiments have been carried out to model the magnetic reconnection process in a solar flare with powerful lasers. Relativistic electrons with energy up to megaelectronvolts. are detected along the magnetic separatrices bounding the reconnection outflow, which exhibit a kappa-like distribution with an effective temperature of similar to 10(9) K. The acceleration of non-thermal electrons is found to be. more efficient in the case with a guide magnetic field (a component of a. magnetic field along the reconnection-induced electric field) than. in the case without a guide field. Hardening of the spectrum at energies >= 500 keV is observed in both cases, which remarkably resembles the hardening. of hard X-ray and gamma-ray spectra observed in many solar flares. This supports a recent proposal that the hardening in the hard X-ray and gamma-ray emissions of solar flares is due to a hardening of the source-electron spectrum. We also performed numerical simulations that help examine behaviors of electrons in the reconnection process with the electromagnetic field configurations occurring in the experiments. The trajectories of non-thermal electrons observed in the experiments were well duplicated in the simulations. Our numerical simulations generally reproduce the electron energy spectrum as well, except for. the hardening of the electron spectrum. This suggests that other mechanisms such as shock or turbulence may play an important role in the production. of the observed energetic electrons.