Comparison of Polarized Radiative Transfer Codes Used by the EHT Collaboration
Journal article, 2023

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.

Author

Ben Prather

Los Alamos National Laboratory

Jason Dexter

JILA

M. Mościbrodzka

Radboud University

Hung-Yi Pu

Academia Sinica

National Taiwan Normal University

Thomas Bronzwaer

Radboud University

Jordy Davelaar

Radboud University

Flatiron Institute

Columbia University

Ziri Younsi

University College London (UCL)

Goethe University Frankfurt

Charles F. Gammie

University of Illinois

R. Gold

University of Southern Denmark

George N. Wong

Princeton University

Institute for Advanced Studies

Kazunori Akiyama

Harvard University

Massachusetts Institute of Technology (MIT)

National Astronomical Observatory of Japan

Antxon Alberdi

Spanish National Research Council (CSIC)

Walter Alef

Max Planck Society

Juan-Carlos Algaba

University of Malaya

Richard Anantua

Harvard University

Harvard-Smithsonian Center for Astrophysics

University of Texas

K. Asada

Academia Sinica

R. Azulay

Universitat de Valencia

Max Planck Society

U. Bach

Max Planck Society

A. K. Baczko

Max Planck Society

David Ball

University of Arizona

Mislav Baloković

Yale University

John Barrett

Massachusetts Institute of Technology (MIT)

M. Bauböck

University of Illinois

Bradford A. Benson

Fermi National Accelerator Laboratory

University of Chicago

Dan Bintley

James Clerk Maxwell Telescope

East Asian Observatory

Lindy Blackburn

Harvard-Smithsonian Center for Astrophysics

Harvard University

Raymond Blundell

Harvard-Smithsonian Center for Astrophysics

K. L. Bouman

California Institute of Technology (Caltech)

G. C. Bower

Academia Sinica

University of Hawaii

Hope Boyce

McGill University

M. Bremer

Institut de Radioastronomie Millimétrique (IRAM)

C. D. Brinkerink

Radboud University

Roger Brissenden

Harvard-Smithsonian Center for Astrophysics

Harvard University

Silke Britzen

Max Planck Society

Avery E. Broderick

Perimeter Institute for Theoretical Physics

University of Waterloo

D. Broguière

Institut de Radioastronomie Millimétrique (IRAM)

Sandra Bustamente

University of Massachusetts

Do Young Byun

University of Science and Technology (UST)

Korea Astronomy and Space Science Institute

J. E. Carlstrom

University of Chicago

Chiara Ceccobello

Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics

A. Chael

Princeton University

Chi Kwan Chan

Princeton University

University of Arizona

Dominic O. Chang

Harvard University

Harvard-Smithsonian Center for Astrophysics

Koushik Chatterjee

Harvard University

Harvard-Smithsonian Center for Astrophysics

S. Chatterjee

Cornell University

Ming Tang Chen

Cornell University

Yongjun Chen

Chinese Academy of Sciences

X. P. Cheng

Korea Astronomy and Space Science Institute

I. Cho

Spanish National Research Council (CSIC)

Pierre Christian

Fairfield University

Nicholas S. Conroy

Harvard-Smithsonian Center for Astrophysics

University of Illinois

John Conway

Chalmers, Space, Earth and Environment, Onsala Space Observatory

James M. Cordes

Cornell University

Thomas M. Crawford

University of Chicago

G. Crew

Massachusetts Institute of Technology (MIT)

Alejandro Cruz-Osorio

Goethe University Frankfurt

Yuzhu Cui

Zhejiang Lab

Shanghai Jiao Tong University

Mariafelicia De Laurentis

National Institute for Nuclear Physics

University of Naples Federico II

Goethe University Frankfurt

R. P. Deane

University of Witwatersrand

Rhodes University

University of Pretoria

Jessica Dempsey

James Clerk Maxwell Telescope

Netherlands Institute for Radio Astronomy (ASTRON)

East Asian Observatory

Gregory Desvignes

Max Planck Society

Paris Observatory

Vedant Dhruv

University of Illinois

S. Doeleman

Harvard University

Harvard-Smithsonian Center for Astrophysics

Sean Dougal

University of Arizona

Sergio A. Dzib

Institut de Radioastronomie Millimétrique (IRAM)

Max Planck Society

Ralph P. Eatough

Chinese Academy of Sciences

Max Planck Society

Razieh Emami

Harvard-Smithsonian Center for Astrophysics

H.D. Falcke

Radboud University

Joseph R. Farah

University of California

Las Cumbres Observatory Global Telescope Network

V. Fish

Massachusetts Institute of Technology (MIT)

E. Fomalont

National Radio Astronomy Observatory

H. Alyson Ford

University of Arizona

R. Fraga-Encinas

Radboud University

William T. Freeman

Google Inc.

Massachusetts Institute of Technology (MIT)

P. Friberg

East Asian Observatory

James Clerk Maxwell Telescope

Christian M. Fromm

Goethe University Frankfurt

Max Planck Society

University of Würzburg

Antonio Fuentes

Spanish National Research Council (CSIC)

Peter Galison

Harvard University

Roberto Garcia

Institut de Radioastronomie Millimétrique (IRAM)

Olivier Gentaz

Institut de Radioastronomie Millimétrique (IRAM)

Boris Georgiev

University of Waterloo

Perimeter Institute for Theoretical Physics

C. Goddi

Istituto nazionale di astrofisica (INAF)

University of Cagliari

University of Sao Paulo (USP)

National Institute for Nuclear Physics

Arturo I. Gómez-Ruiz

National Council for Science and Technology Mexico

National Institute of Astrophysics, Optics and Electronics

J. L. Gomez

Spanish National Research Council (CSIC)

Minfeng Gu

Chinese Academy of Sciences

M. Gurwell

Harvard-Smithsonian Center for Astrophysics

K. Hada

National Astronomical Observatory of Japan

The Graduate University for Advanced Studies (SOKENDAI)

Daryl Haggard

McGill University

Kari Haworth

Harvard-Smithsonian Center for Astrophysics

Michael H. Hecht

Massachusetts Institute of Technology (MIT)

R. Hesper

University of Groningen

Dirk Heumann

University of Arizona

Luis C. Ho

Beijing University of Technology

Paul Ho

Academia Sinica

East Asian Observatory

James Clerk Maxwell Telescope

Mareki Honma

The Graduate University for Advanced Studies (SOKENDAI)

University of Tokyo

National Astronomical Observatory of Japan

Chih Wei L. Huang

Academia Sinica

Lei Huang

Chinese Academy of Sciences

D. Hughes

National Institute of Astrophysics, Optics and Electronics

Shiro Ikeda

National Astronomical Observatory of Japan

University of Tokyo

The Graduate University for Advanced Studies (SOKENDAI)

The Institute of Statistical Mathematics

C. M. V. Impellizzeri

Georgia Institute of Technology

National Radio Astronomy Observatory

Leiden University

Astrophysical Journal

0004-637X (ISSN) 1538-4357 (eISSN)

Vol. 950 1 35

RadioNet 4

European Commission (EC) (EC/H2020/730562), 2017-01-01 -- 2020-12-31.

Onsala space observatory infrastructure

Swedish Research Council (VR) (2017-00648), 2018-01-01 -- 2021-12-31.

Subject Categories (SSIF 2011)

Astronomy, Astrophysics and Cosmology

DOI

10.3847/1538-4357/acc586

More information

Latest update

7/23/2026