Abstract: For about two decades, the IceCube Neutrino Observatory has been detecting ~TeV-PeV neutrinos from mostly unidentified extraterrestrial sources. Active galactic nuclei (AGN), powered by supermassive black holes, are theoretically among the most likely source candidates. However, observationally, their connection remains tenuous so far. Despite the detection of a few hundred extragalactic neutrinos, only a handful of AGNs can be considered as likely neutrino emitters. Namely, NGC 1068 (a Seyfert-II AGN) is the hottest spot in the diffuse ~TeV neutrino sky and TXS 0506+056 (a jetted AGN with its jet oriented toward Earth, i.e., a blazar) constitutes the most promising source candidate with individual ≳100 TeV neutrinos.

In my talk, I will review our current understanding of the AGN–neutrino connection. I will discuss how the limited angular resolution of the current generation of the neutrino data has made establishing a connection between AGN and neutrinos so challenging. I will then present variability as a powerful tool to leverage the precise arrival time of the neutrinos in order to overcome this limitation. Lastly, I will showcase recent results from the most extensive blazar–neutrino spatio-temporal correlation studies where jetted-AGN variability played a central role in the correlation search.