Teddy Cheung, NRL
Fermi LAT Observations of Gamma-ray Flaring in the Gravitationally Lensed Blazar B0218+357
Beginning mid-2012, increased gamma-ray activity from the radio double-imaged gravitationally lensed blazar B0218+357 was observed with the Fermi Large Area Telescope (LAT). The sustained flaring with daily fluxes greater than 10x the source's nominal level afforded an opportunity to uniquely measure the expected gravitational lens delay in gamma rays. Additionally, Fermi-LAT pointed observations of the anticipated delayed emission from the brightest flares with peaks ~60x its nominal flux at the end of September 2012 allowed us to constrain the magnification ratio between the images in gamma-rays. We will present the results from our timing and spectral analysis of B0218+357 and consider prospects for future LAT studies of gravitationally lensed systems.

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