On the connection of the apparent proper motion and the VLBI stucture of compact radio sources  

S. Frey1,2, A. Moór2,3 and O.A. Titov4

1Satellite Geodetic Observatory, Institute of Geodesy, Cartography and Remote Sensing, Hungary
2Research Group for Physical Geodesy and Geodynamics, Hungarian Academy of Sciences, Hungary
3Konkoly Observatory, Hungarian Academy of Sciences, Hungary
4 Geoscience Australia, Australia

Oral presentation

There is evidence for the apparent proper motions of the compact extragalactic sources that are used as fiducial points to define the celestial reference frame. These changes can be as high as several hundred micro-arcseconds per year. On the other hand, when imaged with Very Long Baseline Interferometry (VLBI) at milli-arcsecond (mas) angular resolution, these sources typically show extended structures with a dominant compact "core" and a one-sided "jet". The long-term positional instability of the sources is generally believed to be connected with the changes in the source structure. Here we investigate a sample of more than 70 radio-loud active galactic nuclei with good time series of astrometric positions as well as detailed mas-scale radio brightness distribution models. We compare the direction of their proper motions and their characteristic jet direction, and conclude that these directions are statistically not correlated. We introduce our method, and discuss the possible implications of our result.