Jet Lamp-Post Models for Radio-Loud AGN

• Applicant: Dr. Thomas Dauser
• Subject Area: Astrophysics and Astronomy
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 443220636

Features indicative of reflection of X-ray radiation from the inner accretion disk are found in the X-ray spectra of many Active Galactic Nuclei (AGN). Due to relativistic effects imprinted on these features, it is possible to measure parameters such as the spin of the black hole and the location of the primary source of X-rays. Detailed studies in the last two decades have shown that in radio-quiet AGN this primary source, also called the "corona", is very compact and close to the black hole. It has been suggested that such a compact corona could be the base of a compact jet launching regio. While reflection and the primary X-ray source have mainly been studied in Seyfert galaxies, relativistic reflection has also been detected in recent observations of radio-loud AGN. In phase 1 of this project we developed an improved model to investigate the location of the corona in radio-loud AGN. We implemented a spectral fitting model for a ring-like corona that is able to model any axisymmetric jet launching region and allows us to put constraints on the extent of the corona. Following up on the application of the model on a small radio-loud sample, we will improve the model in phase 2 to include a magnetized accretion disk to overcome the strong simplification of a razor-thin disk in current reflection models. Additionally, we will develop a framework to use general relativistic magneto hydrodynamic (GRMHD) simulations of the jets from this sample to predict the reflection. Both models will be compared to the radio-loud AGN sample, which will allow us to investigate in detail if the X-ray corona is the base of the relativistic jet and analyze any difference to their radio-quiet counter-parts.

• DFG Programme: Research Units
• Subproject of: FOR 5195: Relativistic Jets in Active Galaxies
• Co-Investigator: Professor Dr. Jörn Wilms