Barnacka, Anna, Geller, Margaret J., Dell'Antonio, Ian P., and Zitrin, Adi. 2016. "The Structure of the Strongly Lensed Gamma-Ray Source B2 0218 35." The Astrophysical Journal 821:58. https://doi.org/10.3847/0004-637X/821/1/58
Strong gravitational lensing is a powerful tool for resolving the high-energy universe. We combine the temporal resolution of Fermi-LAT, the angular resolution of radio telescopes, and the independently and precisely known Hubble constant from the analysis by the Planck collaboration, to resolve the spatial origin of gamma-ray flares in the strongly lensed source B2 0218 35. The lensing model achieves 1 mas spatial resolution of the source at gamma-ray energies. The data imply that the gamma-ray flaring sites are separate from the radio core: the bright gamma-ray flare (MJD: 56160-56280) occurred 51 /- 8 pc from the 15 GHz radio core, toward the central engine. This displacement is significant at the ˜ 3σ level, and is limited primarily by the precision of the Hubble constant. B2 0218 35 is the first source where the position of the gamma-ray emitting region relative to the radio core can be resolved. We discuss the potential of an ensemble of strongly lensed high-energy sources for elucidating the physics of distant variable sources based on data from Chandra and SKA.