Proper motion of reference radio sources

TL;DR

This paper investigates the causes of observed systematic proper motions in distant radio sources, distinguishing intrinsic jet motions from potential systematic effects, and discusses the implications for VLBI measurements.

Contribution

It identifies the sources of systematic proper motions in radio sources and analyzes their impact on astrometric measurements.

Findings

Relativistic jet motions can mimic proper motion in VLBI observations.

Systematic effects are larger than those caused by Solar system rotation.

The study discusses potential causes of these systematic motions.

Abstract

The motion of relativistic jets from the active extragalactic nuclei can reach several hundred microseconds per year and mimic proper motion of the distant radio sources observed by VLBI. Such motion of individual quasar is not correlated and its magnitude exceeds the small systematic effects induced by the rotation of the Solar system around the centre of the Galaxy. In this paper we search for the cause of the systematic effect and discuss the results.