Identification of a New $\gamma$-ray-emitting narrow-line Seyfert 1 Galaxy, at Redshift $\sim1$

TL;DR

This paper reports the discovery of a distant gamma-ray-emitting narrow-line Seyfert 1 galaxy at redshift 0.966, expanding the known population and providing insights into its spectral and variability characteristics.

Contribution

It identifies and characterizes the most distant gamma-ray-emitting NLS1 galaxy, demonstrating its spectral features and modeling its emission with a one-zone leptonic jet model.

Findings

Most distant gamma-ray-emitting NLS1 at z=0.966

Spectral energy distribution fits a leptonic jet model

Shows high radio brightness and rapid infrared variability

Abstract

We report on the identification of a new $\gamma$-ray-emitting narrow-line Seyfert 1 (NLS1) galaxy, SDSS J122222.55+041315.7, which increases the number of known objects of this remarkable but rare type of active galactic nuclei (AGN) to seven. Its optical spectrum, obtained in the Sloan Digital Sky Survey-Baryon Oscillation Spectroscopic Survey, reveals a broad H $\beta$ emission line with a width (FWHM) of 1734$\pm$104 km s$^{-1}$. This, along with strong optical Fe II multiplets [$R_{4570}=0.9$] and a weak [O III] $\lambda 5007$ emission line, makes the object a typical NLS1. On the other hand, the source exhibits a high radio brightness temperature, rapid infrared variability, and a flat X-ray spectrum extending up to $\sim$200 keV. It is associated with a luminous $\gamma$-ray source detected significantly with {\it Fermi}/LAT. Correlated variability with other wavebands has not yet been tested. The spectral energy distribution can be well modelled by a one-zone leptonic jet model. This new member is by far the most distant $\gamma$-ray-emitting NLS1, at a redshift of $z=0.966$.