WoU-MMA: Multi-messenger Signatures of Ion Acceleration in Active Galactic Nuclei

The supermassive black holes at the center of galaxies are extreme astrophysical machines that control the evolution of their environments. They are sources of high-velocity winds and relativistic jets, and they are associated with the highest-energy particles in the Universe. They emit electromagnetic radiation from radio to gamma-ray, and they have been associated recently with the production of very-high-energy astrophysical neutrinos. The origin of these particles is a multidisciplinary field, with relevance to astrophysics, space physics, and laboratory plasmas. Connecting multi-messenger astrophysics with space and plasma communities amplifies the message that plasma physics is crucial for understanding the Universe. The project will train graduate students in astroplasmaphysics and provide new concepts and discoveries to the broader public. Multi-messenger observatories have provided the first clues of high-energy ion acceleration in active galactic nuclei (AGNs). The goal of this project is to unravel the physical processes that are responsible for the acceleration of ions in AGN outflows. The PIs will use a semi-analytical formalism, validated by kinetic plasma simulations, to model acceleration at AGN wind shocks and relativistic magneto-hydrodynamic simulations with tracked test-particles to calculate the spectrum of UHECRs and neutrinos expected from AGN jets. They will address the following questions: (1) How are ions accelerated in AGN winds, and what is their multi-messenger signature? (2) What are the diffuse and source ultra-high-energy cosmic ray and neutrino spectra produced by AGN jets? (3) Is there an interplay between winds and jets in producing energetic cosmic rays and neutrinos? This award advances the goals of the Windows on the Universe Big Idea. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.