We have performed a very long baseline interferometry (VLBI) survey of local (z < 0.05) ultrahard X-ray (14–195 keV) selected active galactic nuclei (AGNs) from the Swift Burst Alert Telescope (BAT) using KVN, KaVA, and VLBA. We first executed fringe surveys of 142 BAT-detected AGNs at 15 or 22 GHz. Based on the result from the fringe surveys and archival data, we find 10/279 nearby AGN (∼4 per cent) VLBI have 22 GHz flux above 30 mJy. This implies that the X-ray AGNs with a bright nuclear jet are not common. Among these 10 radio-bright AGNs, we obtained 22 GHz VLBI imaging data of our own for four targets and reprocessed archival data for six targets. We find that, although our 10 AGNs observed with VLBI span a wide range of pc-scale morphological types, they lie on a tight linear relation between accretion luminosity and nuclear jet luminosity. Our result suggests that a powerful nuclear radio jet correlates with the accretion disc luminosity. We also probed the Fundamental Plane of black hole activity at VLBI scales (e.g. few milliarcsecond). The jet luminosity and size distribution among our sample roughly fit into the proposed AGN evolutionary scenario, finding powerful jets after the blow-out phase based on the Eddington ratio (λEdd)–hydrogen column density (NH) relation. In addition, we find some hints of gas inflow or galaxy–galaxy merger in the majority of our sample. This implies that gas supply via tidal interactions in galactic scale may help the central AGN to launch a powerful parsec-scale jet.
Bibliographical noteFunding Information:
We thank the anonymous referee for his/her valuable comments and suggestions that helped to improve the paper. We are grateful to the staff of the KVN who helped to operate the array and to correlate the data. The KVN and a high-performance computing cluster are facilities operated by the KASI (Korea Astronomy and Space Science Institute). The KVN observations and correlations are supported through the high-speed network connections among the KVN sites provided by the KREONET (Korea Research Environment Open NETwork), which is managed and operated by the KISTI (Korea Institute of Science and Technology Information). In addition, this work is based on observations made with the KaVA and VLBA, which are operated by the Korea Astronomy and Space Science Institute and the National Astronomical Observatory of Japan and the National Radio Astronomy Observatory which is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc., respectively. The VLBA data was correlated by the Swinburne University of Technology software correlator, developed as part of the Australian Major National Research Facilities Programme and operated under licence. Support for this work was provided by the National Research Foundation of Korea to the Center for Galaxy Evolution Research (No. 2017R1A5A1070354), and NRF grant No. 2015R1D1A1A0106051 and 2018R1D1A1B07048314. JB acknowledges support from NRF through Young Researchers’ Exchange Programme Between Korea and Switzerland 2016 (No. 2016K1A3A1A14953055). KO acknowledges support from the Japan Society for the Promotion of Science (JSPS, ID: 17321). MK acknowledges support from NASA through ADAP award NNH16CT03C. CR acknowledges the CONICYT+PAI Convoca-toria Nacional subvencion a instalacion en la academia convocatoria año 2017 PAI77170080. YU acknowledges the financial support by JSPS Grant-in-Aid for Scientific Research 17K05384.
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science