FERMIMONITORING OF RADIO-LOUD NARROW-LINE SEYFERT 1 GALAXIES

Abstract

We present detailed analysis of the gamma-ray flux variability and spectral properties of the five radio-loud narrow line Seyfert 1 (RL-NLSy1) galaxies, detected by the Large Area Telescope onboard the Fermi Gamma-ray Space Telescope, namely 1H 0323+342, SBS 0846+513, PMN J0948+0022, PKS 1502+036, and PKS 2004$-$447. The first three sources show significant flux variations including the rapid variability of a few hours by 1H 0323+342. The average gamma-ray spectrum of 1H 0323+342 and PMN J0948+0022 shows deviation from a simple power law (PL) behavior, whereas for other three sources, PL model gives better fit. The spectra of 1H 0323+342, SBS 0846+513, and PMN J0948+0022, respectively in low, flaring, and moderately active states, show significant curvature. Such curvature in the gamma-ray spectrum of 1H 0323+342 and PMN J0948+0022 can be due to emission region located inside the broad line region (BLR) where the primary mechanism of the gamma-ray emission is inverse-Compton (IC) scattering of BLR photons occurring in the Klein-Nishina regime. The gamma-ray emission of SBS 0846+513 is explained by IC scattering of dusty torus photons which puts the emission region to be outside the BLR and thus under the Thomson regime. Therefore, the observed curvature of SBS 0846+513 could be intrinsic to the particle energy distribution. The presence of curvature in the gamma-ray spectrum and flux variability amplitudes of some of the RL-NLSy1 galaxies suggest that these sources could be akin to low/moderate jet power flat spectrum radio quasars.