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arXiv · 2303.12004

Comparison of Polarized Radiative Transfer Codes used by the EHT Collaboration

Cora Prather·Jason Dexter·Monika Moscibrodzka·Hung-Yi Pu·Thomas Bronzwaer·Jordy Davelaar·Ziri Younsi·Charles F. Gammie·Roman Gold·George N. Wong·Kazunori Akiyama·Antxon Alberdi·Walter Alef·Juan Carlos Algaba·Richard Anantua·Keiichi Asada·Rebecca Azulay·Uwe Bach·Anne-Kathrin Baczko·David Ball·Mislav Baloković·John Barrett·Michi Bauböck·Bradford A. Benson·Dan Bintley·Lindy Blackburn·Raymond Blundell·Katherine L. Bouman·Geoffrey C. Bower·Hope Boyce·Michael Bremer·Christiaan D. Brinkerink·Roger Brissenden·Silke Britzen·Avery E. Broderick·Dominique Broguiere·Sandra Bustamante·Do-Young Byun·John E. Carlstrom·Chiara Ceccobello·Andrew Chael·Chi-kwan Chan·Dominic O. Chang·Koushik Chatterjee·Shami Chatterjee·Ming-Tang Chen·Yongjun Chen·Xiaopeng Cheng·Ilje Cho·Pierre Christian·Nicholas S. Conroy·John E. Conway·James M. Cordes·Thomas M. Crawford·Geoffrey B. Crew·Alejandro Cruz-Osorio·Yuzhu Cui·Mariafelicia De Laurentis·Roger Deane·Jessica Dempsey·Gregory Desvignes·Vedant Dhruv·Sheperd S. Doeleman·Sean Dougal·Sergio A. Dzib·Ralph P. Eatough·Razieh Emami·Heino Falcke·Joseph Farah·Vincent L. Fish·Ed Fomalont·H. Alyson Ford·Raquel Fraga-Encinas·William T. Freeman·Per Friberg·Christian M. Fromm·Antonio Fuentes·Peter Galison·Roberto García·Olivier Gentaz·Boris Georgiev·Ciriaco Goddi·Arturo I. Gómez-Ruiz·José L. Gómez·Minfeng Gu·Mark Gurwell·Kazuhiro Hada·Daryl Haggard·Kari Haworth·Michael H. Hecht·Ronald Hesper·Dirk Heumann·Luis C. Ho·Paul Ho·Mareki Honma·Chih-Wei L. Huang·Lei Huang·David H. Hughes·Shiro Ikeda·C. M. Violette Impellizzeri
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Abstract

Interpretation of resolved polarized images of black holes by the Event Horizon Telescope (EHT) requires predictions of the polarized emission observable by an Earth-based instrument for a particular model of the black hole accretion system. Such predictions are generated by general relativistic radiative transfer (GRRT) codes, which integrate the equations of polarized radiative transfer in curved spacetime. A selection of ray-tracing GRRT codes used within the EHT collaboration is evaluated for accuracy and consistency in producing a selection of test images, demonstrating that the various methods and implementations of radiative transfer calculations are highly consistent. When imaging an analytic accretion model, we find that all codes produce images similar within a pixel-wise normalized mean squared error (NMSE) of 0.012 in the worst case. When imaging a snapshot from a cell-based magnetohydrodynamic simulation, we find all test images to be similar within NMSEs of 0.02, 0.04, 0.04, and 0.12 in Stokes I, Q, U , and V respectively. We additionally find the values of several image metrics relevant to published EHT results to be in agreement to much better precision than measurement uncertainties.

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Cora Prather, Jason Dexter, Monika Moscibrodzka, Hung-Yi Pu, Thomas Bronzwaer, Jordy Davelaar, Ziri Younsi, Charles F. Gammie, Roman Gold, George N. Wong, Kazunori Akiyama, Antxon Alberdi, Walter Alef, Juan Carlos Algaba, Richard Anantua, Keiichi Asada, Rebecca Azulay, Uwe Bach, Anne-Kathrin Baczko, David Ball, Mislav Baloković, John Barrett, Michi Bauböck, Bradford A. Benson, Dan Bintley, Lindy Blackburn, Raymond Blundell, Katherine L. Bouman, Geoffrey C. Bower, Hope Boyce, Michael Bremer, Christiaan D. Brinkerink, Roger Brissenden, Silke Britzen, Avery E. Broderick, Dominique Broguiere, Sandra Bustamante, Do-Young Byun, John E. Carlstrom, Chiara Ceccobello, Andrew Chael, Chi-kwan Chan, Dominic O. Chang, Koushik Chatterjee, Shami Chatterjee, Ming-Tang Chen, Yongjun Chen, Xiaopeng Cheng, Ilje Cho, Pierre Christian, Nicholas S. Conroy, John E. Conway, James M. Cordes, Thomas M. Crawford, Geoffrey B. Crew, Alejandro Cruz-Osorio, Yuzhu Cui, Mariafelicia De Laurentis, Roger Deane, Jessica Dempsey, Gregory Desvignes, Vedant Dhruv, Sheperd S. Doeleman, Sean Dougal, Sergio A. Dzib, Ralph P. Eatough, Razieh Emami, Heino Falcke, Joseph Farah, Vincent L. Fish, Ed Fomalont, H. Alyson Ford, Raquel Fraga-Encinas, William T. Freeman, Per Friberg, Christian M. Fromm, Antonio Fuentes, Peter Galison, Roberto García, Olivier Gentaz, Boris Georgiev, Ciriaco Goddi, Arturo I. Gómez-Ruiz, José L. Gómez, Minfeng Gu, Mark Gurwell, Kazuhiro Hada, Daryl Haggard, Kari Haworth, Michael H. Hecht, Ronald Hesper, Dirk Heumann, Luis C. Ho, Paul Ho, Mareki Honma, Chih-Wei L. Huang, Lei Huang, David H. Hughes, Shiro Ikeda, C. M. Violette Impellizzeri. 2026-07-23. Comparison of Polarized Radiative Transfer Codes used by the EHT Collaboration. https://doi.org/10.3847/1538-4357%2Facc586

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