Speaker
Description
Summary
We report on Fermi Large Area Telescope (LAT) detection of long-lived gamma-ray emission from the Sun during 2011 March 7 to 8.
At 19:43 UT on 7 March 2011, GOES X-ray monitor observed the onset of M3.7 solar flare. Following the flare, gamma-rays above 100 MeV was detected by Fermi/LAT with high significance.
The flux was at least higher than the Vela pulsar, which is the brightest steady source in the gamma-ray band.
The gamma-ray emission lasted at least 9 hours, and the spectrum (E>100 MeV) accumulated during the flare duration was relatively soft.
Rhessi and Fermi/GBM did not detect such a long-lasting hard X-ray emission during the LAT detection.
Considering the lack of hard X-ray emission, decay of pions produced by accelerated protons would be responsible for the LAT emission.
We discuss these possible emission mechanisms.
