Jetted narrow-line Seyfert 1 galaxies breaking the jet paradigm: A comprehensive study of host-galaxy morphologies

¹ Aalto University Metsähovi Radio Observatory, Metsähovintie 114, 02540 Kylmälä, Finland
e-mail: irene.bjorklund@aalto.fi
² Aalto University Department of Electronics and Nanoengineering, PO Box 15500, 00076 Aalto, Finland
³ European Space Agency (ESA), European Space Astronomy Centre (ESAC), Camino Bajo del Castillo s/n, 28692 Villanueva de la Cañada, Madrid, Spain
⁴ European Southern Observatory (ESO), Alonso de Córdova 3107, Casilla 19, Santiago 19001 , Chile
⁵ Finnish Centre for Astronomy with ESO (FINCA), University of Turku, Vesilinnantie 5, 20014 University of Turku, Finland
⁶ Dipartimento di Fisica e Astronomia “G. Galilei”, Universitá di Padova, Vicolo dell’Osservatorio 3, 35122 Padova, Italy
⁷ Departamento de Astronomía, Universidad de Chile, Camino del Observatorio 1515, 7591245 Las Condes, Santiago, Chile

Received: 11 July 2022
Accepted: 13 September 2022

Abstract

Narrow-line Seyfert 1 (NLS1) galaxies are unevolved active galactic nuclei (AGNs) that exist predominantly in spiral galaxies. However, mostly due to the small number of sources studied, it has been under debate whether also the hosts of jetted NLS1 galaxies, a particular subclass of these sources hosting a relativistic jet, are disk-like or elliptical, as the hosts of more powerful jetted AGNs. We studied the host morphologies of 14 NLS1 galaxies, 11 of which have been detected at 37 GHz, indicating that these sources harbour relativistic jets. The J- and Ks-band data used in this study were obtained with the Nordic Optical Telescope (NOT). We performed the photometric decomposition of the host galaxy using the band that gave a better fit and additionally created colour maps of all sources that had both a J- and a Ks-band observation. We were able to successfully model 12 sources, nine of which most likely have disk-like morphologies. Of the remaining sources, one source could possibly be hosted either in a disk-like or a dwarf galaxy, and in two cases the results are inconclusive. Only one of our sources shows clear signs of interaction, but the colour maps of most of our sources hint at ample dust in the nuclei, possibly indicating earlier minor mergers, which can go unnoticed due to the limited resolution of these observations. Our results further support disk-like galaxies as the predominant host type of jetted NLS1 galaxies. Most importantly, with the number of modelled hosts of jetted NLS1s now exceeding 50, with only a few elliptical hosts, it seems to be safe to conclude that also disk-like galaxies are able to launch and maintain relativistic jets, and that the traditional jet paradigm stating that only massive elliptical galaxies are capable of hosting relativistic jets is severely outdated.