Fermi Gamma-ray Space Telescope

VERITAS detection & ongoing kinematic monitoring of Radio Galaxy 3C 264

Eileen Meyer
(for the VERITAS Collaboration)


In March of 2018, the VERITAS Collaboration announced the discovery of very-high-energy emission (VHE; >100 GeV) from the FRI radio galaxy 3C 264, currently the most distant radio galaxy yet detected. This source is also the most distant target for which kiloparsec-scale proper motions have been detected in a radio/optical jet. As first reported in Meyer et al., (2015), two superluminal knots in the jet (speeds of 7c and 3c) are in the process of an internal-shock collision, which has lead to a slow brightening of the collision zone in the jet. Fortunately for the timing of the VHE flare, we have been monitoring 3C 264 with VLA, HST, and VLBA observations since 2015/2016 in order to trace the ongoing knot collision, and were also able to obtain additional VLA, VLBA and Chandra DD observations, providing an excellent multi-wavelength dataset to examine the connection of the VHE flare to specific wavelengths and locations in the jet. From the monitoring data, we find that the brightening of the jet has continued over the last three years. I will present updated kinematics of the full jet profile, from parsec (VLBI) to kpc (HST/VLA) scales, as well as the updated VERITAS results from continued monitoring of 3C 264 throughout the spring.