MuSES: Multi-messenger Studies of Extragalactic Super-colliders
Taking a further step in AGN studies by using a multimessenger approach aimed at probing jet formation and collimation, particle acceleration, and neutrino production mechanisms in blazars.
ERC Advanced Grant (No 101142396) — Principal Investigator: Prof. Dr. Yuri Kovalev
Project Duration: January 2025 - December 2029
Active galactic nuclei (AGN) are among the universe’s most powerful particle accelerators, converting the gravitational energy of matter accreted onto supermassive black holes (SMBHs) into electromagnetic and kinetic energy. This process produces relativistic electrons and protons, often launched as highly collimated bipolar jets along the black hole’s rotational axis. These jets originate within tens of gravitational radii from the SMBH and are accelerated to relativistic speeds on larger scales, as indicated by superluminal motion, high Doppler factors, and extreme brightness temperatures.
AGN have long been considered potential sources of high-energy neutrinos, with mechanisms including particle cascades, magnetic reconnection, and tidal disruption events. In recent years, the detection of astrophysical neutrinos in the TeV–PeV range — most notably from the blazar TXS 0506+056 by the IceCube Neutrino Observatory — has strengthened the case for such associations.
Objectives
MuSES is dedicated to uncovering the physical processes near supermassive black holes that drive the launching and propagation of relativistic jets in AGN. The project investigates how black hole properties, accretion flows, and the ambient medium shape jet acceleration and collimation, including the transition from electromagnetic to kinetic energy dominance. A key focus is on understanding proton acceleration and neutrino production mechanisms. Through this work, MuSES aims to advance our understanding of the role of black holes and relativistic outflows in AGN energy release, high-energy neutrino emission, and cosmic-ray production. These investigations can provide the most accurate constrains on the extreme energy output of AGN, turning them into well-understood cosmic laboratories capable of probing physical conditions unattainable by any experiments on Earth.
Methods
Radio-to-gamma-ray observations, especially very-long-baseline interferometry, are combined with high-energy neutrino data from global observatories to investigate the physical mechanisms responsible for neutrino production in blazars. The approach includes:
Identifying re-collimation signatures in jet morphology and conducting multi-year VLBI kinematic analyses to trace relativistic plasma flows;
Parsec-scale studies of neutrino-associated blazars using regular polarization VLBI monitoring of complete samples, complemented by neutrino-triggered follow-up experiments;
Reconstructing the physical conditions inside AGN jets by analyzing newly ejected components that coincide with high-energy neutrino events;
Unraveling the connection between multi-wavelength variability and neutrino production via statistical and physical modeling of synchro-Compton flares and their temporal alignment with neutrino arrivals.
