Radio and gamma-ray loud narrow-line Seyfert 1 galaxies in the spotlight

Narrow-line Seyfert 1 (NLS1) galaxies provide us with unique insights into the drivers of AGN activity under extreme conditions. Given their low black hole (BH) masses and near-Eddington accretion rates, they represent a class of galaxies with rapidly growing supermassive BHs in the local universe. Here, we present the results from our multi-frequency radio monitoring of a sample of {\gamma}-ray loud NLS1 galaxies ({\gamma}NLS1s), including systems discovered only recently, and featuring both the nearest and the most distant {\gamma}NLS1s known to date. We also present high-resolution radio imaging of 1H 0323+342, which is remarkable for its spiral or ring-like host. Finally, we present new radio data of the candidate {\gamma}-emitting NLS1 galaxy RX J2314.9+2243, characterized by a very steep radio spectrum, unlike other {\gamma}NLS1s.