Discovery of gamma-ray emission from a strongly lobe-dominated quasar 3C 275.1

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We systematically analyze the 6-year Fermi/LAT data of the lobe-dominated quasars (LDQs) in the complete LDQ sample from 3CRR survey and report the discovery of high-energy γ-ray emission from 3C 275.1. The γ-ray emission of 3C 207 is confirmed and significant variability of the lightcurve is identified. We do not find statistically significant γ-ray emission from other LDQs. 3C 275.1 is the known γ-ray quasar with the lowest core dominance parameter (i.e., R=0.11). We also show that both the northern radio hotspot and parsec jet models can reasonably reproduce the γ-ray data. The parsec jet model, however, is favored by the potential γ-ray variability at the timescale of months. We suggest that some dimmer γ-ray LDQs will be detected in the future and LDQs could contribute non-negligibly to the extragalactic γ-ray background.