Fermi Large Area Telescope observations of the Sun: The first ten years

Abstract

The Fermi Large Area Telescope (LAT) observations of the active Sun provide the largest sample of detected solar flares with emission greater than 30 MeV to date. These include detections of impulsive and sustained emission, extending up to 20 hours in the case of the 2012 March 7 X-class flares. Of particular interest is the first detection of >100 MeV gamma-ray emission from three solar flares whose positions behind the limb were confirmed by the STEREO spacecrafts. The LAT data provides a new observational channel that, when combined with observations from across the electromagnetic spectrum, provide a unique opportunity to diagnose the mechanisms of high-energy emission and particle acceleration in solar flares. We will present an overview of these observations including the emission of the Sun in its quiescent state and discuss how these observations provide constrains on different emission mechanisms.

Characteristics of Sustained >100 MeV Gamma-ray Emission Associated with Solar Flares

“…Much of the information comes from the NOAA solar event reports 4 . Column 1 lists the event number, column 2 lists the date of the event and location of the flare or centroid of the hard X-ray footpoints imaged by RHESSI, column 3 lists the GOES soft X-ray class (we used estimates made by Pesce-Rollins et al (2015b) for the location and GOES class for the two events beyond the limb) and the GOES start and stop times, column 4 lists the projected CME speed from the SOHO LASCO catalog 5 (unless noted), column 5 lists the Type II metric intensity from the solar event reports ("?" means that we could not confirm the detection spectroscopically), and whether decameter-hectometric (DH) Type II emission 6 was observed in space (Y/N), column 6 lists the peak SEP proton flux above 10 MeV in pfu (1 proton cm −2 sr −1 s −1 ) and highest energy measured at the best magnetically connected spacecraft, and column 7 lists the highest energy channel that the impulsive flare was detected by RHESSI or GBM in hard X-rays.…”