Monitoring the Bi-Directional Relativistic Jets of the Radio Galaxy 1946+708

TL;DR

This study uses multi-frequency VLBI observations to analyze the kinematics of jets in the radio galaxy 1946+708, revealing their age, ejection patterns, and possible helical confinement.

Contribution

It provides detailed measurements of jet component velocities, ages, and ejection events, and suggests a helical jet structure, advancing understanding of jet dynamics in CSOs.

Findings

Jet components travel at 0.6 to 0.9c.

Jet ejections occur approximately every 10 years.

The source's age is about 4000 years.

Abstract

We report on a multi-frequency, multi-epoch campaign of Very Long Baseline Interferometry observations of the radio galaxy 1946+708 using the VLBA and a Global VLBI array. From these high-resolution observations we deduce the kinematic age of the radio source to be $\sim$4000 years, comparable with the ages of other Compact Symmetric Objects (CSOs). Ejections of pairs of jet components appears to take place on time scales of 10 years and these components in the jet travel outward at intrinsic velocities between 0.6 and 0.9 c. From the constraint that jet components cannot have intrinsic velocities faster than light, we derive H_0 > 57 km s^-1 Mpc^-1 from the fastest pair of components launched from the core. We provide strong evidence for the ejection of a new pair of components in ~1997. From the trajectories of the jet components we deduce that the jet is most likely to be helically confined, rather than purely ballistic in nature.