2-6 September 2024
CJD Bonn Castell
Europe/Berlin timezone
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Contribution

CJD Bonn Castell

Bayesian calibration and imaging in VLBI

Speakers

  • Mr. Jongseo KIM

Primary authors

Co-authors

Content

Calibration and imaging are closely interconnected in very long baseline interferometry (VLBI). The conventional CLEAN algorithm has been widely employed for imaging, self-calibration, and polarization calibration. However, forward modeling and Bayesian imaging algorithms have recently outperformed CLEAN, and these new imaging methods can also be utilized for various aspects of data calibration. This talk describes a new approach we have developed for extending the Bayesian imaging framework RESOLVE to include self-calibration and polarization calibration of VLBI data. Applications of this approach to imaging of 43 GHz VLBA and 86 GHz GMVA+ALMA observations of M87 show that high-resolution images and antenna-based gain solutions with uncertainty estimation can be obtained. Ongoing developments of Bayesian polarization calibration and imaging will be illustrated with the example of analysis of 15 GHz MOJAVE data for 3C273. Based on this analysis, we conclude that the Bayesian approach can be successfully extended to include the elements of self-calibration and instrumental polarization, thus allowing for robust, high fidelity recovery of pivotal structural characteristics of the emitting regions, including, for the examples mentioned above, the faint, extended jet emission and the photon ring in M87 and the internal structure of the total intensity and polarized emission in jet in 3C273. These results provide strong evidence for the Bayesian calibration and imaging approach to be very well suitable for image reconstruction from VLBI data.