Volume 578, June 2015
|Number of page(s)||18|
|Published online||10 June 2015|
Structure of the nucleus of 1928+738⋆
1 Institut d’Astrophysique, UPMC Univ. Paris 06, CNRS, UMR 7095, 98bis Bd Arago, 75014 Paris, France
2 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
3 Department of Experimental Physics, University of Szeged, Dóm tér 9, 6720 Szeged, Hungary
4 Department of Theoretical Physics, University of Szeged, Tisza Lajos krt 84-86, 6720 Szeged, Hungary
5 Laboratoire d’Astrophysique, Observatoire de Grenoble, 414 rue de la Piscine, Domaine Universitaire, 38400 Saint-Martin d’ Hères, France
6 Observatoire de Paris, SYRTE, CNRS, UPMC, CRGS, 75014 Paris, France
Received: 26 September 2014
Accepted: 16 December 2014
Modeling trajectories of VLBI components ejected by the nucleus of 1928+738 shows that the VLBI jet contains three trajectory families, meaning that the VLBI components are ejected from three different origins. The fit of components C1, C6, and C8 indicates that the nucleus of 1928+738 contains two binary black hole systems. The first is associated with the stationary components Cg and CS and is characterized by a radius Rbin,1 ≈ 0.220 mas; both black holes ejected VLBI components almost regularly between 1990 and 2010. The second binary black hole system is not associated with stationary components and is characterized by a radius Rbin,2 ≈ 0.140 mas; it ejected only three VLBI components between 1994 and 1999. The two black hole systems are separated by ≈1.35 mas. We briefly discuss the consequences of the existence of binary black holes systems in radio quasars to make the link between radio quasars and Gaia.
Key words: astrometry / galaxies: jets / galaxies: individual: 1928+738
Appendices are available in electronic form at http://www.aanda.org
© ESO, 2015
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