Speaker
Description
$\gamma$-ray emitting narrow-line Seyfert 1 galaxies ($\gamma$-NLS1) are jetted, $\gamma$- and radio-loud sources of a very puzzling sub-class of Active Galactic Nuclei (AGN), exhibiting properties similar to low power flat-spectrum radio quasars (FSRQs), but not quite identical. They are characterised by relatively low black hole masses and extremely high, near-Eddington accretion rates, with some members of this class showing very rapid and large amplitude flaring episodes, the main physical mechanism of which is still not fully understood. In order to better constrain it, we selected various $\gamma$-ray activity states for two genuine $\gamma$-NLS1 1H 0323$+$342 and PMN J0948$+$0022, one intermediate object between $\gamma$-NLS1 and FSRQ classes, B2 0954$+$25A, and a bright FSRQ 3C 279, for which we analysed an extensive set of multi-wavelength data and retrieved a maximum number of observational constraints, that were used in the multi-epoch and multi-component modelling of the sources. For each target and period of interest, we tested two different physical scenarii, where the high energy $\gamma$-ray radiation is produced by the inverse Compton scattering of the disc and broad-line region (BLR) or torus photons by relativistic electrons of the jet. Disc and BLR- dominated scenario was favored and the transition from low to high activity states is well explained by particle injection on a stationary emission zone in the jet. Total jet powers of the sources are quantified to investigate the nature of $\gamma$-NLS1 and FSRQs.
