Identification of a new γ-ray-emitting narrow-line Seyfert 1 galaxy, at redshift ∼1

Abstract

We report on the identification of a new γ-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 to seven. Its optical spectrum, obtained in the Sloan Digital Sky Survey-Baryon Oscillation Spectroscopic Survey, reveals a broad H β emission line with a width (FWHM) of 1734 ± 104 km s^-1. This, along with strong optical Fe II multiplets [R₄₅₇₀ = 0.9] and a weak [O III] λ5007 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 ∼200 keV. It is associated with a luminous γ-ray source detected significantly with 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 γ-ray-emitting NLS1, at a redshift of z = 0.966.