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Dr. Felix Pötzl

Biography

Originally from Bonn, Germany, I did my bachelor degree in physics and subsequently my master degree in astrophysics at the University of Bonn. In 2021, I obtained my PhD degree working at the Max-Planck-Institute for radio astronomy on space-VLBI studies of the quasar 3C 345, focusing on properties of magnetic fields in the parsec-scale jet. Since September 2021 I am working as a lecturer and researcher at the physics department of UCC.

Research Interests

My research focuses on studying the properties of relativistic jets in active galactic nuclei (AGN). Those are the very compact (parsec-scale), active centres of galaxies, where accretion onto a supermassive black hole (SMBH) powers the so-called central engine, which produces radiation across the whole electromagnetic spectrum. I want to study the properties of the relativistic outflows (jets) emanating along the rotational axis of the black hole. Those jets are bright in the radio due to synchrotron emission, generated by the relativistic particles gyrating in an underlying magnetic field.

 

Many theoretical models for jet launching predict a helical magnetic field structure in the jet, which can partly be probed with observations of the linear polarisation at very high resolution. The high resolution is provided by Very-Long-Baseline Interferometry (VLBI), an interferometer connecting telescopes around the globe, yielding milli-arcsecond resolution. This resolution is improved even further by including antennas in space (space-VLBI, e.g. RadioAstron project). Combining observations at several frequencies, the observed rotation of the linear polarisation angle due to Faraday rotation can provide hints at the magnetic field structure along the line of sight.

 

Measurements of the relative position of the compact feature at the jet base (core) can also be used to derive the magnetic field strength and particle density in the jet. This is due to the frequency-dependence of the core position in a synchrotron-self-absorbed jet. Extending these measurements of the ‘core-shift’ to higher frequencies, and thus probing magnetic fields deeper into the jet and closer to the SMBH, is another focus of my research. This is enabled by a new generation of multi-frequency receivers at VLBI-stations, making core-shift measurements possible at higher frequencies and providing unprecedented precision in the measurements.

 

A combination of these methods can provide a more complete picture of the strength, orientation and origin of magnetic fields in AGN jets, which in turn provides crucial insights on how these peculiar objects form and evolve in space and time.

 

Publications

See my Orcid profile for publications: https://orcid.org/0000-0002-6579-8311

 

Teaching Activity

2021/2022: PY2104 Introduction to Thermodynamics and Statistical Physics