Broadband observations of the gamma-ray emitting narrow line Seyfert 1 galaxy SBS 0846+513

Abstract

We present the results of our broadband study of the γ -ray emitting narrow line Seyfert 1 ( NLSy1 ) galaxy SBS 0846 + 513 ( z = 0.585 ) . This includes multiband fl ux variations, γ -ray spectral analysis, broadband spectral energy distribution ( SED ) modeling, and intranight optical variability ( INOV ) observations carried out over six nights between 2012 November and 2013 March using the 2 m Himalayan Chandra Telescope and the 1.3 m telescope at Devasthal, India. Multiple episodes of fl aring activity are seen in the γ -ray light curve of the source which are also re fl ected in the observations at lower frequencies. A statistically signi fi cant curvature is noticed in the seven years averaged γ -ray spectrum, thus indicating its similarity with powerful fl at spectrum radio quasars ( FSRQs ) . Modeling the SEDs with a one-zone leptonic emission model hints that the optical UV spectrum is dominated by synchrotron radiation, whereas inverse Compton scattering of broad line region photons reproduces the γ -ray part of the SEDs. The source was found to be variable on all the six nights of optical observations with a variation of ∼ 0.3 mag within a single night, coinciding with a high γ -ray activity state. The observed large amplitude INOV clearly indicates the presence of a closely aligned beamed relativistic jet in SBS 0846 + 513. Our broadband study supports the recent claims in literature that γ -ray emitting NLSy1 galaxies are similar to blazars and constitute the low black hole mass counterparts to FSRQs.