Evolution of the Termination Region of the Parsec-Scale Jet of 3C 84 Over the Past 20 Years

TL;DR

This study tracks the evolution of the parsec-scale jet in 3C 84 over 20 years, revealing new superluminal components and suggesting intrinsic acceleration mechanisms beyond simple viewing angle changes.

Contribution

It provides the first long-term VLBA observations showing superluminal motions and discusses physical mechanisms like jet precession and magnetic reconnection.

Findings

C3 component maintained a constant velocity of ~0.259c over 20 years.

Four new subcomponents emerged with apparent speeds exceeding that of C3.

The fastest subcomponent showed an apparent speed of 1.22c.

Abstract

We present the kinematics of the parsec-scale jet in 3C 84 from 2003 November to 2022 June observed with the Very Long Baseline Array (VLBA) at 43 GHz. We find that the C3 component, a bright feature at the termination region of the jet component ejected from the core in 2003, has maintained a nearly constant apparent velocity of 0.259 +/- 0.003c over the period covered by observations. We observe the emergence of four new subcomponents from C3, each exhibiting apparent speeds higher than that of C3. Notably, the last two subcomponents exhibit apparent superluminal motion, with the fastest component showing an apparent speed of 1.22 +/- 0.14c. Our analysis suggests that a change in viewing angle alone cannot account for the fast apparent speeds of the new subcomponents, indicating that they are intrinsically faster than C3. We identify jet precession (or reorientation), a jet-cloud collision, and magnetic reconnection as possible physical mechanisms responsible for the ejection of the new subcomponents.