Multiwavelength monitoring of the enigmatic Narrow-Line Seyfert 1 PMN J0948+0022 in March-July 2009

TL;DR

This study presents a comprehensive multiwavelength monitoring of the gamma-ray emitting Narrow-Line Seyfert 1 galaxy PMN J0948+0022, revealing jet activity and variability patterns similar to blazars, confirming the presence of powerful relativistic jets.

Contribution

First multiwavelength campaign of PMN J0948+0022 demonstrating jet activity and variability, establishing similarities with blazar properties in a Narrow-Line Seyfert 1 galaxy.

Findings

Detected activity across all wavelengths with flux variations up to a factor of 4 in X-rays.

Observed day-scale optical variability with flux changes up to a factor of 3.

Jet power comparable to that of average blazars, supporting the presence of relativistic jets.

Abstract

Following the recent discovery of gamma rays from the radio-loud narrow-line Seyfert 1 galaxy PMN J0948+0022 (z=0.5846), we started a multiwavelength campaign from radio to gamma rays, which was carried out between the end of March and the beginning of July 2009. The source displayed activity at all the observed wavelengths: a general decreasing trend from optical to gamma-ray frequencies was followed by an increase of radio emission after less than two months from the peak of the gamma-ray emission. The largest flux change, about a factor of about 4, occurred in the X-ray band. The smallest was at ultraviolet and near-infrared frequencies, where the rate of the detected photons dropped by a factor 1.6-1.9. At optical wavelengths, where the sampling rate was the highest, it was possible to observe day-scale variability, with flux variations up to a factor of about 3. The behavior of PMN J0948+0022 observed in this campaign and the calculated power carried out by its jet in the form of protons, electrons, radiation and magnetic field are quite similar to that of blazars, specifically of flat-spectrum radio quasars. These results confirm the idea that radio-loud narrow-line Seyfert 1 galaxies host relativistic jets with power similar to that of average blazars.