A1 Refereed original research article in a scientific journal
Analytical ray-tracing of synchrotron emission around accreting black holes
Authors: Veledina, Alexandra; Pélissier, Matthieu
Publisher: EDP Sciences
Publishing place: LES ULIS CEDEX A
Publication year: 2025
Journal: Astronomy and Astrophysics
Journal name in source: Astronomy & Astrophysics
Journal acronym: ASTRON ASTROPHYS
Article number: A273
Volume: 693
Number of pages: 18
ISSN: 0004-6361
eISSN: 1432-0746
DOI: https://doi.org/10.1051/0004-6361/202452557
Web address : https://doi.org/10.1051/0004-6361/202452557
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/485102283
Polarimetric images of accreting black holes encode important information about laws of strong gravity and relativistic motions of matter. Recent advancements in instrumentation have enabled such studies of two objects: the supermassive black holes M87* and Sagittarius A*. Light coming from these sources is produced by a synchrotron mechanism whose polarization is directly linked to magnetic field lines, and propagates toward the observer in a curved spacetime. We studied the distortions of the gas image by employing the analytical ray-tracing technique for polarized light ARTPOL, which is adapted for the case of synchrotron emission. We derived analytical expressions for fast conversion of the intensity or flux, polarization degree, and polarization angle from the local coordinates to those of the observer. We placed an emphasis on the nonzero matter elevation above the equatorial plane and noncircular matter motions. Applications of the developed formalism include static polarimetric imaging of the black hole vicinity and dynamic polarimetric signatures of matter close to the compact object.
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Funding information in the publication:
AV acknowledges support the Academy of Finland grant 355672. Nordita is supported in part by NordForsk.
