Teddy Cheung (NRC/Naval Research Lab)

Two Surprises from the Fermi Large Area Telescope

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, observes the high-energy (>100 MeV) gamma-ray sky with unprecedented sensitivity and resolution. Its default mode of observations over its now 2+ years of operation is to scan the entire sky every ~3 hrs, making it especially well-suited to detect and characterize transient and variable sources. Amongst the handful of transients in the Galactic plane detected so far was the surprise discovery of GeV emission from a nova, a source type previously unexpected as a high-energy gamma-ray emitter. The continuous accumulation of all-sky exposure from the LAT scanning observations also allows for the study of persistent sources. This led naturally to yet another unexpected result -- the detection of the giant radio lobes (angular size ~10 degree) of a nearby radio galaxy imaged in gamma-rays. The results of these two surprises from the Fermi-LAT will be presented.