# 37 GHz observations of narrow-line Seyfert 1 galaxies

## TL;DR

This study presents 37 GHz radio observations of 78 narrow-line Seyfert 1 galaxies, revealing that many host relativistic jets and exhibit blazar-like variability, suggesting jets are more common in NLS1s than previously thought.

## Contribution

First comprehensive 37 GHz radio survey of NLS1 galaxies showing prevalent jet activity and blazar-like spectral properties.

## Key findings

- 19% detection rate at 37 GHz
- Many NLS1s show blazar-like spectra and variability
- High-frequency emission likely from relativistic jets

## Abstract

Observations at 37 GHz, performed at Mets\"ahovi Radio Observatory, are presented for a sample of 78 radio-loud and radio-quiet narrow-line Seyfert 1 (NLS1) galaxies, together with additional lower and higher frequency radio data from RATAN-600, Owens Valley Radio Observatory, and the Planck satellite. Most of the data have been gathered between February 2012 and April 2015 but for some sources even longer lightcurves exist. The detection rate at 37 GHz is around 19%, comparable to other populations of active galactic nuclei presumed to be faint at radio frequencies, such as BL Lac objects. Variability and spectral indices are determined for sources with enough detections. Based on the radio data, many NLS1 galaxies show a blazar-like radio spectra exhibiting significant variability. The spectra at a given time are often inverted or convex. The source of the high-frequency radio emission in NLS1 galaxies, detected at 37 GHz, is most probably a relativistic jet rather than star formation. Jets in NLS1 galaxies are therefore expected to be a much more common phenomenon than earlier assumed.