DISCOVERY OF gamma-RAY EMISSION FROM THE STRONGLY LOBE-DOMINATED QUASAR 3C 275.1

Abstract

We systematically analyze the 6 year Fermi/Large Area Telescope (LAT) data on lobe-dominated quasars (LDQs) in the complete LDQ sample from the Revised third Cambridge Catalogue of Radio Sources (3CRR) survey and report the discovery of high-energy gamma-ray emission from 3C 275.1. The gamma-ray emission of 3C 207 is confirmed and significant variability of the light curve is identified. We do not find statistically significant gamma-ray emission from other LDQs. 3C 275.1 is the known gamma-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 gamma-ray data. The parsec jet model, however, is favored by the potential gamma-ray variability on a timescale of months. We suggest that some dimmer gamma-ray LDQs will be detected in the future and LDQs could contribute non-ignorably to the extragalactic gamma-ray background