Description:

Astrophysical neutrinos, the “ghost particles of the Cosmos”, are unique probes of the physical conditions in their sources, as they can escape from them and reach Earth almost unimpeded due to their extremely weak interactions with matter and radiation. High-energy neutrinos, which are mainly produced by inelastic collisions of relativistic protons or heavier nuclei with radiation or matter, can be used to trace the elusive sources of cosmic rays and to shed light on the underlying particle acceleration mechanisms. Active galactic nuclei (AGN) with relativistic jets powered by accretion onto their central supermassive black hole are the most powerful persistent sources of electromagnetic radiation in the Universe, with bolometric luminosities of ~1e43-1e48 erg/s. Jetted AGN are promising cosmic ray accelerators and have abundant radiation fields for the production of high-energy neutrinos. As a result, they have been suggested as possible neutrino sources long before the discovery of an astrophysical neutrino flux by IceCube. The recent discovery of a high-energy neutrino coincident with an electromagnetic flare from a blazar (TXS 0506+056) offers a unique opportunity to probe the physics of these powerful extragalactic sources using multiple messengers (i.e., photons and neutrinos). In this talk, I will review the lessons learned and the challenges created from the first high-energy neutrino source association to date. 

Speaker: Maria Petropoulou, Princeton

Host: Ian Christie

Keywords: Physics, Astronomy, Astrophysics