GAMMA-RAY UPPER LIMITS on MAGNETARS with SIX YEARS of FERMI-LAT OBSERVATIONS

© 2017. The American Astronomical Society. All rights reserved. We report on the search for gamma-ray emission from 20 magnetars using six years of Fermi Large Area Telescope observations. No significant evidence for gamma-ray emission from any of the currently known magnetars is found. We derived the most stringent upper limits to date on the 0.1-10 GeV emission of Galactic magnetars, which are estimated between ∼10-12 and 10-11 erg s-1 cm-2. We searched gamma-ray pulsations for the four magnetars having reliable ephemerides over the observing period, but detected none. We also report updated morphologies and spectral properties of seven spatially extended gamma-ray sources, which are most likely attributed to supernova remnants associated with or adjacent to the magnetars.