Active galactic nuclei (AGNs) are empirically divided into ‘radio-loud’ and ‘radio-quiet’. These 50-year-old labels are obsolete, misleading and wrong. I argue that AGNs should be classified as ‘jetted’ and ‘non-jetted’ based on a physical difference — the presence (or lack) of strong relativistic jets.
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Acknowledgements
I thank C. Circosta, C. Ferrari, E. Hatziminaoglou, A. Merloni, F. Panessa, and E. Resconi for helpful comments and C. M. Harrison for producing Fig. 1.
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Padovani, P. On the two main classes of active galactic nuclei. Nat Astron 1, 0194 (2017). https://doi.org/10.1038/s41550-017-0194
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DOI: https://doi.org/10.1038/s41550-017-0194
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