Universität zu Köln

Kim, Jong-Seo ORCID: 0009-0008-2431-6874 (2025). Bayesian calibration and imaging in radio interferometry. PhD thesis, Universität zu Köln.

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Abstract

This dissertation presents a Bayesian framework for joint calibration and imaging in radio interferometry. Traditional methods, such as AIPS, CASA, and DIFMAP, treat calibration and imaging separately, even though both rely on shared prior knowledge about the source and instrument. The Bayesian approach developed here, implemented in the Bayesian imaging resolve software, overcomes this limitation by jointly inferring calibration and image parameters, naturally accounting for calibration uncertainties in the final reconstruction. Using variational inference to mitigate computational costs, this method achieves high-fidelity and super-resolved images while providing uncertainty estimates for calibration and imaging results. The framework is extended to include polarimetric calibration, enabling robust full-Stokes imaging. The approach is validated on observations of active galactic nuclei (AGNs), key targets for studying black hole accretion and jet formation. Applications include: galaxy M87 at 43 and 86 GHz (VLBA, GMVA+ALMA), revealing the black hole shadow and jet with improved resolution and quantified uncertainties in ring parameters, Quasar 3C273 (VLBA, 15 GHz) and blazar OJ287 (GMVA+ALMA, 86 GHz), producing reliable polarimetric images and instrumental calibration (gains, D-terms), and radio galaxy Hydra A (VLA, 2.5 GHz), demonstrating full Bayesian calibration and imaging using resolve. Altogether, this dissertation demonstrates that Bayesian calibration and imaging approach for full polarimetric radio interferometric data can reconstruct reliable calibration solutions and images with high resolution and provide better observational constraints with uncertainties to understand the inner structure of AGNs and their jet formation.

Item Type:	Thesis (PhD thesis)
Creators:	Creators Email ORCID ORCID Put Code Kim, Jong-Seo jongkim@mpifr-bonn.mpg.de https://orcid.org/0009-0008-2431-6874 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-801541
Date:	2025
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Unspecified
Subjects:	Physics
Uncontrolled Keywords:	Keywords Language methods: statistical English techniques: high angular resolution English techniques: image processing English techniques: interferometric English galaxies: active English galaxies: individual: M87 English polarization English galaxies: jets English UNSPECIFIED English
Date of oral exam:	17 October 2025
Referee:	Name Academic Title Zensus, J. Anton Prof. Dr. Riechers, Dominik A. Prof. Dr. Shao, Yaping Prof. Dr.
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/80154