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Polarimetric Geometric Modeling for mm-VLBI Observations of Black Holes by Roelofs, Freek; Johnson, Michael D.; Chael, Andrew; Janssen, Michael; Wielgus, Maciek; Broderick, Avery E.; Collaboration, The Event Horizon Telescope is a scholarly article available to read on EtoBox.

What is Polarimetric Geometric Modeling for mm-VLBI Observations of Black Holes about?

The Event Horizon Telescope (EHT) is a millimeter very long baseline interferometry (VLBI) array that has imaged the apparent shadows of the supermassive black holes M87* and Sagittarius A*. Polarimetric data from these observations contain a wealth of information on the black hole and accretion flow properties. In this work, we develop polarimetric geometric modeling methods for mm-VLBI data, focusing on approaches that fit data products with differing degrees of invariance to broad classes of calibration errors. We establish a fitting procedure using a polarimetric "m-ring" model to approximate the image structure near a black hole. By fitting this model to synthetic EHT data from general relativistic magnetohydrodynamic models, we show that the linear and circular polarization structure can be successfully approximated with relatively few model parameters. We then fit this model to EHT observations of M87* taken in 2017. In total intensity and linear polarization, the m-ring fits are consistent with previous results from imaging methods. In circular polarization, the m-ring fits indicate the presence of event-horizon-scale circular polarization structure, with a persistent dipol

Author

Roelofs, Freek; Johnson, Michael D.; Chael, Andrew; Janssen, Michael; Wielgus, Maciek; Broderick, Avery E.; Collaboration, The Event Horizon Telescope

Published

2023

Language

EN