Jet Physics on Event Horizon Scales and Beyond

• Applicants: Dr. Christian Fromm; Professor Dr. Eduardo Ros, Ph.D.
• Subject Area: Astrophysics and Astronomy
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 443220636

This project aims at understanding the formation, structure, and high-energy emissions of relativistic jets in active galactic nuclei (AGN), using a combination of observational and computational approaches. We have already made significant contributions, particularly through high-resolution imaging of AGN jets with the Event Horizon Telescope (EHT), Global Millimeter VLBI Array (GMVA), and complementary modeling using general relativistic magnetohydrodynamics (GRMHD). The preliminary work included building a library of jet simulations, analyzing EHT observations of nearby AGNs like NGC 1052 and Centaurus A (Cen A), and developing tools for direct comparison between simulated and observed data. These efforts revealed key features such as jet asymmetries, edge-brightened structures, and magnetic field configurations close to the black hole, which are critical for understanding jet launching mechanisms. The proposed research continues and expands this work by addressing three central questions: how AGN jets are launched, how they are collimated over vast scales, and how they generate high-energy emissions. The project will study three AGNs with different orientations and power levels —NGC 1052, Cen A, and the blazar 4C +01.28 using newly acquired EHT and GMVA data. Observational data will be matched with advanced GRMHD and general relativistic radiative transfer (GRRT) simulations. These simulations will incorporate physical processes such as resistivity, particle heating and acceleration, radiation transport, and the team will use cutting-edge artificial intelligence and machine learning techniques to optimize model fitting and analysis. This unified and observationally guided framework aims to break degeneracies in theoretical models and provide a more accurate picture of AGN jet physics. The project is structured into two main work packages: WP1 focuses on processing and analyzing EHT/GMVA observations, while WP2 involves numerical modeling of jet launching, propagation, and radiation processes. WP1 includes data calibration, imaging, and extraction of spectral and polarimetric properties. WP2 will expand the existing simulation library with non-ideal effects and integrate them with synthetic observations. The simulations will also model high-energy and neutrino emissions to connect jet behavior to multi-messenger astrophysical phenomena. The combination of multi-wavelength observations, theoretical modeling, and AI-driven data analysis positions this project at the forefront of AGN research and will contribute significantly to our understanding of jet dynamics and black hole environments.

• DFG Programme: Research Units
• Subproject of: FOR 5195: Relativistic Jets in Active Galaxies
• International Connection: United Kingdom
• Co-Investigators: Professor Dr. Matthias Kadler; Professor Dr. J. Anton Zensus
• Cooperation Partner: Dr. Ziri Younsi