Speaker
Description
Blazars are a class of AGN characterised by relativistic jets pointed towards our LoS. Traditionally, they are classified into two families: BL Lacs (no emission lines suggesting an inefficient accretion flow and faint bluer broad band SEDs) and FSRQs (strong emission lines, radiatively efficient accretion and brighter red SEDs). However, recent studies have highlighted that blazars identified as potential neutrino emitters show unusual spectral properties which don't allow a standard classification. I will present the analysis of a spectroscopic sample of neutrino-emitter blazars. Many of these sources exhibit peculiar spectral features that have led to their interpretation as masquerading BL Lacs, i.e. blazars whose powerful jet emission hides the spectral signatures of a radiatively efficient accretion disk. To better understand their nature, we use the broad emission lines as tracer of the ionising disc luminosity, and thus constrain their accretion regime, most likely transitional between standard and inefficient. We exploit the interplay between spectroscopic analysis and broad band photometric data, comparing the results obtained from these two independent methods. This approach allows us to investigate whether these sources are intrinsically efficient accretors whose emission lines are diluted by the jet, or they represent a distinct population. Understanding their accretion properties and emission mechanisms will also provide important clues about the connection between blazars and high-energy neutrino emission, lately linked also to non-jetted AGN.