Multi-messenger Studies of Extragalactic Super-colliders

Introduction

Active galactic nuclei (AGN) are among the most powerful particle accelerators in the Universe. They convert the gravitational energy of matter accreted by supermassive black holes (SMBHs) into electromagnetic and kinetic energy, producing highly relativistic electrons and protons. They are most likely originated from the vicinity of SMBHs, but the exact mechanism of their production remains elusive.

Particle Acceleration

Electrons are predominantly found in jets, whose acceleration and collimation are still poorly understood. Even less clear is how and where protons are accelerated and how this process is connected to neutrino production. The importance of investigating such high-energy particles transcends astrophysics, as they probe regimes that particle accelerators on Earth will likely never reach.

Recent Developments

The recent detection of a high-energy neutrino signal from the blazar TXS 0506+056 by the IceCube Neutrino Observatory has brought up new multi-messenger opportunities for AGN studies which can be now most efficiently explored.

Proposal Objectives

This proposal sets its main aim on carrying out such an exploration and addressing the pivotal questions about:

1. Proton acceleration
2. Jet formation and collimation
3. Neutrino production in AGN

To achieve these goals, we will perform and utilize observations of AGN across the electromagnetic spectrum, with a particular focus on high-resolution very-long-baseline interferometry and data collected by high-energy neutrino telescopes.

Expected Outcomes

The information and insight gathered through these investigations will provide the most accurate clues about the extreme energy output in AGN and transform these objects into well-understood cosmic laboratories which can probe physical conditions unachievable in any experiments performed on Earth.