Unprecedented change in the position of four radio sources

• Main Authors: Frey, S. (Author), González, J. (Author), Gulayev, S. (Author), Lambert, S. (Author), Melnikov, A. (Author), Natusch, T. (Author), Shu, F. (Author), Tercero, B. (Author), Titov, O. (Author), Weston, S. (Author), Xia, B. (Author)
• Format: Article
• Language: English
• Published: Oxford University Press 2022
• Subjects: Active galactic nuclei; astrometry; Astrometry; Celestial reference frame; Extragalactic radio sources; Galaxies; Galaxies active; Galaxies jets; galaxies: active; galaxies: jets; Proper motion; Radio astronomy; radio continuum: galaxies; Radio continuum: galaxies; reference systems; Reference systems; Very long baseline interferometry
• Online Access: View Fulltext in Publisher

 Astrometric positions of radio-emitting active galactic nuclei (AGNs) can be determined with sub-milliarcsec accuracy using very long baseline interferometry (VLBI). The usually small apparent proper motion of distant extragalactic targets allow us to realize the fundamental celestial reference frame with VLBI observations. However, long-term astrometric monitoring may reveal extreme changes in some AGN positions. Using new VLBI observations in 2018-2021, we show here that four extragalactic radio sources (3C 48, CTA 21, 1144+352, 1328+254) have a dramatic shift in their positions by 20-130 mas over two decades. For all four sources, the apparent positional shift is caused by their radio structure change. © 2022 Commonwealth of Australia [2022]. The Article has been produced using funding provided by Geoscience Australia.