Gamma-ray emission and particle acceleration mechanisms of solar flares

自2008年发射以来，费米-LAT已经在几十次事件中探测到了大量的太阳耀斑伽马射线。MeV/GeV的γ射线谱在几百MeV处显示出清晰而显著的转换，表明γ射线是通过π介子衰变过程产生的。大光子统计使我们能够确定发射区的位置，我们发现伽马射线发射点位于太阳表面的活动区周围。这意味着高能质子是在活动区产生的，湍流加速是最合理的选择。特别是，从z=1.1的blazar PKS 0426-380附近探测到了2个非常高能量的伽马射线光子。

Since the launch in 2008, Fermi-LAT has detected a lot of solar flare gamma-rays over several tens of events. The MeV/GeV gamma-ray spectra showed clear and significant turnover at several hundreds of MeV, indicating that the gamma-rays are produced via pion-decay process. The large photon statistics allowed us to pin-down the location of the emission region and we found that the gamma-ray emission site is around the Active Region on the solar surface. This implies that high-energy protons are produced at the Active region and that turbulent acceleration would be the most plausible option.Fermi data analysis for Active Galactic Nuclei (AGN) were also performed. In particular, 2 very-high-energy gamma-ray photons were detected from the close vicinity of the z=1.1 blazar PKS 0426-380.