EVN observations of low-luminosity flat-spectrum active galactic nuclei |
| |
| Authors: | A Caccianiga MJM Marchã A Thean J Dennett-Thorpe |
| |
| Institution: | 1CAAUL, Observatório Astronómico de Lisboa, Tapada da Ajuda, 1349-018 Lisboa, Portugal;2Istituto di Radioastronomia del CNR, Via P. Gobetti 101, I-40129 Bologna, Italy;3University of Groningen, Kapteyn Institute, 9700AV Groningen, the Netherlands |
| |
| Abstract: | We present and discuss the results of very-long baseline interferometry (VLBI, EVN) observations of three low-luminosity  broad emission line active galactic nuclei (AGNs) carefully selected from a sample of flat-spectrum radio sources (CLASS). Based on the total and the extended radio power at 5 and at 1.4 GHz respectively, these objects should be technically classified as radio-quiet AGN and thus the origin of their radio emission is not clearly understood. The VLBI observations presented in this paper have revealed compact radio cores which imply a lower limit on the brightness temperature of about  . This result rules out a thermal origin for the radio emission and strongly suggests an emission mechanism similar to that observed in more powerful radio-loud AGNs. Since, by definition, the three objects show a flat (or inverted) radio spectrum between 1.4 and 8.4 GHz, the observed radio emission could be relativistically beamed. Multi-epoch VLBI observations can confirm this possibility in two years' time. |
| |
| Keywords: | galaxies: active galaxies: Seyfert radio continuum: galaxies |
|
|
