Letter to the Editor

Radio jets and gamma-ray emission in radio-silent narrow-line Seyfert 1 galaxies^★

¹ Aalto University Metsähovi Radio Observatory, Metsähovintie 114, 02540 Kylmälä, Finland
² Aalto University Department of Electronics and Nanoengineering, PO Box 15500, 00076 Aalto, Finland
e-mail: anne.lahteenmaki@aalto.fi
³ Astronomy Department, Universidad de Concepción, Casilla 160-C, Concepción, Chile

Received: 7 May 2018
Accepted: 17 May 2018

Abstract

We have detected six narrow-line Seyfert 1 (NLS1) galaxies at 37 GHz that were previously classified as radio silent and two that were classified as radio quiet. These detections reveal the presumption that NLS1 galaxies labelled radio quiet or radio silent and hosted by spiral galaxies are unable to launch jets to be incorrect. The detections are a plausible indicator of the presence of a powerful, most likely relativistic jet because this intensity of emission at 37 GHz cannot be explained by, for example, radiation from supernova remnants. Additionally, one of the detected NLS1 galaxies is a newly discovered source of gamma rays and three others are candidates for future detections.