Narrow-line Seyfert 1s: what is wrong in a name?

P. Marziani, A. del Olmo, M. D' Onofrio +6

Narrow-line Seyfert 1s (NLSy1s) are an ill-defined class. Work done over the past 20 years as well as recent analyses show a continuity in properties (e.g., Balmer line profiles, b…