A Detailed Kinematic Study of 3C 84 and Its Connection to γ-Rays

Abstract

Abstract 3C 84 (NGC 1275) is the bright radio core of the Perseus cluster. Even in the absence of strong relativistic effects, the source has been detected at γ-rays up to TeV energies. Despite its intensive study, the physical processes responsible for the high-energy emission in the source remain unanswered. We present a detailed kinematics study of the source and its connection to γ-ray emission. The subparsec-scale radio structure is dominated by slow-moving features in both the eastern and western lanes of the jet. The jet appears to have accelerated to its maximum speed within less than 125,000 gravitational radii. The fastest reliably detected speed in the jet was ∼0.9c. This leads to a minimum viewing angle to the source of ≳42° and a maximum Doppler factor of ≲1.5. Our analysis suggests the presence of multiple high-energy sites in the source. If γ-rays are associated with kinematic changes in the jet, they are being produced in both eastern and western lanes in the jet. Three γ-ray flares are contemporaneous with epochs where the slowly moving emission region splits into two subregions. We estimate the significance of these events being associated to be ∼2σ–3σ. We tested our results against theoretical predictions for magnetic-reconnection-induced mini-jets and turbulence and find them compatible.