Three Decades of Very Long Baseline Interferometry Monitoring of the Parsec-Scale Jet in 3C 345

TL;DR

This study reviews 30 years of VLBI observations of quasar 3C 345, revealing insights into jet evolution, kinematics, and physical processes influencing relativistic outflows in active galactic nuclei.

Contribution

It provides a comprehensive analysis of long-term jet behavior combining data from multiple VLBI campaigns since 1979, highlighting physical and geometrical factors affecting jet dynamics.

Findings

Jet trajectories and flux densities vary over time.

Evidence of precession and relativistic shocks in the jet.

Physical instabilities influence jet morphology.

Abstract

The 16th magnitude quasar 3C 345 (redshift z=0.5928) shows structural and emission variability on parsec scales around a compact unresolved radio core. For the last three decades it has been closely monitored with very long baseline interferometry (VLBI), yielding a wealth of information about the physics of relativistic outflows and dynamics of the central regions in AGN. We present here preliminary results for the long-term jet evolution, based on the 15 GHz monitoring data collected by the MOJAVE survey and various other groups over the last ~14 years and combined with data from earlier VLBI observations of 3C 345 which started in 1979. We discuss the trajectories, kinematics, and flux density evolution of enhanced emission regions embedded in the jet and present evidence for geometrical (e.g. precession) and physical (e.g. relativistic shocks and plasma instability) factors determining the morphology and dynamics of relativistic flows on parsec scales.