|Dr. Marco Berton||SCHEDULED|
European Southern Observatory, Santiago, Chile
Narrow-line Seyfert 1 (NLS1) galaxies are a subclass of active galactic
nuclei (AGN) identified more than 30 years ago, but still not entirely
understood. These objects are likely characterized by rapidly growing
low-mass black holes. Interestingly enough, some of them have been
detected in gamma-rays, a sign that they can harbor powerful
relativistic jets. In my talk I will review their properties, showing
how the true nature of NLS1s is that of early-stage AGN in a recently
triggered activity phase, and how they are connected to other classes
kinematically young jetted AGN. I will also report on the discovery, in
a handful of NLS1s, of relativistic jets remarkably faint at low radio
frequency, but extremely bright and variable at high radio frequency.
New observations of these sources are revealing an increasingly
complicated picture, and I will outline the different scenarios we are
developing to explain this new, unexpected phenomenon.