A compact core-jet structure in the changing-look Seyfert NGC 2617
Journal article, 2021

The nearby face-on spiral galaxy NGC 2617 underwent an unambiguous 'inside-out' multiwavelength outburst in Spring 2013, and a dramatic Seyfert-type change probably between 2010 and 2012, with the emergence of broad optical emission lines. To search for the jet activity associated with this variable accretion activity, we carried out multiresolution and multiwavelength radio observations. Using the very long baseline interferometric (VLBI) observations with the European VLBI Network at 1.7 and 5.0 GHz, we find that NGC 2617 shows a partially synchrotron self-absorbed compact radio core with a significant core shift, and an optically thin steep-spectrum jet extending towards the north up to about 2 pc in projection. We also observed NGC 2617 with the electronic Multi-Element Remotely Linked Interferometer Network at 1.5 and 5.5 GHz, and revisited the archival data of the Very Large Array (VLA) and the Very Long Baseline Array (VLBA). The radio core had a stable flux density of similar to 1.4 mJy at 5.0 GHz between 2013 June and 2014 January, in agreement with the expectation of a supermassive black hole in the low accretion rate state. The northern jet component is unlikely to be associated with the 'inside-out' outburst of 2013. Moreover, we report that most optically selected changing-look active galactic nuclei (AGN) at z < 0.83 are sub-mJy radio sources in the existing VLA surveys at 1.4 GHz, and it is unlikely that they are more active than normal AGN at radio frequencies.

radio continuum: galaxies

galaxies: Seyfert

galaxies: individual: NGC 2617

galaxies: active

galaxies: jets


Jun Yang

Chalmers, Space, Earth and Environment, Onsala Space Observatory

Joint Institute for VLBI in Europe (JIVE)

Zsolt Paragi

Joint Institute for VLBI in Europe (JIVE)

Robert J. Beswick

University of Manchester

Wen Chen

Chinese Academy of Sciences

Ilse M. van Bemmel

Joint Institute for VLBI in Europe (JIVE)

Qingwen Wu

Huazhong University of Science and Technology

Tao An

Chinese Academy of Sciences

Xiaocong Wu

Chinese Academy of Sciences

Lulu Fan

Shandong University

University of Science and Technology of China

J. B. R. Oonk

Leiden University

Netherlands Institute for Radio Astronomy (ASTRON)

Surfsara Bv

Xiang Liu

Chinese Academy of Sciences

Weihua Wang

Changzhou Institute of Technology

Monthly Notices of the Royal Astronomical Society

0035-8711 (ISSN) 1365-2966 (eISSN)

Vol. 503 3 3886-3895

Advanced Radio Astronomy in Europe (RADIONET3)

European Commission (EC) (EC/FP7/283393), 2012-01-01 -- 2015-12-31.

Subject Categories

Astronomy, Astrophysics and Cosmology

Atom and Molecular Physics and Optics

Climate Research



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9/7/2023 1