A γ-ray-emitting NLS1 galaxy, SDSS J095909.51+460014.3, identified by multi-wavelength contemporaneous brightening

Abstract

We report on the identification of a new γ-ray-emitting narrow-line Seyfert 1 galaxy (γ-NLS1), SDSS J095909.51+460014.3 (z = 0.399), by establishing an association with a γ-ray source 4FGL 0959.6+4606, although its low-energy counterpart was suggested to be a radio galaxy (RG) 2MASX J09591976+4603515. Wide-field Infrared Survey Explorer long-term light curves of these two sources reveal diverse infrared variability patterns. Brightenings of 2.5 mag are detected for the former source, while flux decays of 0.5 mag are found for the other one. More importantly, the time that the infrared flux of the NLS1 rises is coincident with the time of flux increase of 4FGL 0959.6+4606. At the same time, no infrared activity of the RG has been observed. A specific analysis of 15-month data from Large Area Telescope aboard Fermi, aimed at the high γ-ray flux state, yields a significant source (TS = 43). The corresponding γ-ray localisation analysis suggests that only the NLS1 falls into the uncertainty area, further supporting the updated association relationship. A broadband spectral energy distribution of SDSS J095909.51+460014.3 has been drawn and well described by the classic single-zone homogeneous leptonic jet model. Its jet properties were investigated and found to be comparable with the known γ-NLS1s.

Intra-night optical variability study of a non-jetted narrow-line Seyfert 1 galaxy: SDSS J163401.94+480940.1

“…Unlike the general population of RLNLSy1s, γ-RLNLSy1s show much stronger INOV similar to blazars, suggesting a connection of relativistic jets with their strong INOV. Despite many similar characteristics such as flat radio spectrum, high brightness temperature, superluminal motion, and γ-ray detection (Yuan et al 2008;Abdo et al 2009a,b,c;Foschini et al 2010;Foschini 2011;D'Ammando et al 2012;Berton et al 2017;D'Ammando et al 2015;Yao et al 2015;Lister 2018;Paliya et al 2018;Yang et al 2018;Yao et al 2019;Foschini et al 2021Foschini et al , 2022Li et al 2023) to blazar class of AGN, an important difference between NLSy1s and blazars is an order of less massive black hole for NLSy1s (10 7 M ⊙ , Grupe & Mathur 2004;Deo et al 2006;Peterson 2011). This makes them to harbor less powerful jets (Angelakis et al 2015;Gu et al 2015;Fuhrmann et al 2016;Paliya 2019).…”