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Published July 29, 2017 | Supplemental Material + Published
Journal Article Open

'Zwicky's Nonet': a compact merging ensemble of nine galaxies and 4C 35.06, a peculiar radio galaxy with dancing radio jets


We report the results of our radio, optical and infrared studies of a peculiar radio source 4C 35.06, an extended radio-loud active galactic nucleus (AGN) at the centre of galaxy cluster Abell 407 (z = 0.047). The central region of this cluster hosts a remarkably tight ensemble of nine galaxies, the spectra of which resemble those of passive red ellipticals, embedded within a diffuse stellar halo of ∼1 arcmin size. This system (named 'Zwicky's Nonet') provides unique and compelling evidence for a multiple-nucleus cD galaxy precursor. Multifrequency radio observations of 4C 35.06 with the Giant Meterwave Radio Telescope (GMRT) at 610, 235 and 150 MHz reveal a system of 400-kpc scale helically twisted and kinked radio jets and outer diffuse lobes. The outer extremities of jets contain extremely steep-spectrum (spectral index −1.7 to −2.5) relic/fossil radio plasma with a spectral age of a few ×(10^7–10^8) yr. Such ultra-steep spectrum relic radio lobes without definitive hotspots are rare and they provide an opportunity to understand the life cycle of relativistic jets and physics of black hole mergers in dense environments. We interpret our observations of this radio source in the context of growth of its central black hole, triggering of its AGN activity and jet precession, all possibly caused by galaxy mergers in this dense galactic system. A slow conical precession of the jet axis due to gravitational perturbation between interacting black holes is invoked to explain the unusual jet morphology.

Additional Information

© 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2017 June 11. Received 2017 June 11; in original form 2016 July 12. We thank the staff of GMRT, IUCAA/IGO and Palomar Observatory for their help during the observations. GMRT is run by the National Centre for Radio Astrophysics of the Tata Institute of Fundamental Research. JB, JJ and PD acknowledge generous support from the Indo-French Center for the Promotion of Advanced Research (Centre Franco-Indien pour la Promotion de la Recherche Avanćee) under programme no. 5204-2. KGB and JJ acknowledge IUCAA's support under the Visiting Associate program. KGB gratefully acknowledges the support received through Faculty Development Programme of the UGC, India. AAM and SGD acknowledge partial support from the NSF grants AST-1413600 and AST-1518308. MBP gratefully acknowledges support by DST INSPIRE Faculty Scheme, New Delhi. We have used images and results from SDSS and funding for SDSS has been provided by the Alfred P. Sloan Foundation, the participating institutions, the National Science Foundation, and the US Department of Energy's Office of Science. This research has made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the NASA. We have used VLA data. The VLA is a facility of the National Radio Astronomy Observatory (NRAO).

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Published - Biju_2017p617.pdf

Supplemental Material - stx1476_Supp.zip


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August 22, 2023
October 17, 2023