The first gamma-ray outburst of a Narrow-Line Seyfert 1 Galaxy: the case of PMN J0948+0022 in July 2010

TL;DR

This paper reports the first observed gamma-ray outburst from a Narrow-Line Seyfert 1 Galaxy, demonstrating extreme gamma-ray luminosity and multiwavelength high activity, challenging previous notions of such sources.

Contribution

It presents the first detection of a gamma-ray outburst in a NLS1 galaxy, expanding understanding of high-energy phenomena in these sources.

Findings

Peak gamma-ray flux exceeded 10^-6 ph cm^-2 s^-1

Observed gamma-ray luminosity reached 10^48 erg s^-1

Multiwavelength data confirmed high activity across spectrum

Abstract

We report on a multiwavelength campaign on the radio-loud Narrow-Line Seyfert 1 (NLS1) Galaxy PMN J0948+0022 (z=0.5846) performed in 2010 July-September and triggered by a high-energy gamma-ray outburst observed by the Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope. The peak flux in the 0.1-100 GeV energy band exceeded, for the first time in this type of source, the value of 10^-6 ph cm^-2 s^-1, corresponding to an observed luminosity of 10^48 erg s^-1. Although the source was too close to the Sun position to organize a densely sampled follow-up, it was possible to gather some multiwavelength data that confirmed the state of high activity across the sampled electromagnetic spectrum. The comparison of the spectral energy distribution of the NLS1 PMN J0948+0022 with that of a typical blazar - like 3C 273 - shows that the power emitted at gamma rays is extreme.