Odyssey: A public GPU-based code for general relativistic radiative transfer in Kerr spacetime

Hung Yi Pu, Kiyun Yun, Ziri Younsi, Suk Jin Yoon

Research output: Contribution to journalArticlepeer-review

32 Citations (Scopus)


General relativistic radiative transfer calculations coupled with the calculation of geodesics in the Kerr spacetime are an essential tool for determining the images, spectra, and light curves from matter in the vicinity of black holes. Such studies are especially important for ongoing and upcoming millimeter/submillimeter very long baseline interferometry observations of the supermassive black holes at the centers of Sgr A∗ and M87. To this end we introduce Odyssey, a graphics processing unit (GPU) based code for ray tracing and radiative transfer in the Kerr spacetime. On a single GPU, the performance of Odyssey can exceed 1 ns per photon, per Runge-Kutta integration step. Odyssey is publicly available, fast, accurate, and flexible enough to be modified to suit the specific needs of new users. Along with a Graphical User Interface powered by a video-accelerated display architecture, we also present an educational software tool, Odyssey-Edu, for showing in real time how null geodesics around a Kerr black hole vary as a function of black hole spin and angle of incidence onto the black hole.

Original languageEnglish
Article number105
JournalAstrophysical Journal
Issue number2
Publication statusPublished - 2016 Apr 1

Bibliographical note

Funding Information:
We thank the anonymous referee for useful comments and suggestions that helped improve the manuscript. We thank Steven V. Fuerst for sharing his code, Hsi-Yu Schive for helpful discussions about GPU programming, and K. Akiyama for discussions on spectral data from Sgr A. H.-Y.P. and Z.Y. are grateful for numerous helpful and stimulating discussions with Kinwah Wu. H.-Y.P. also thanks members of the GLT team for their support and encouragement. H.-Y.P. is supported by the Ministry of Science and Technology (MOST) of Taiwan under the grant MOST 103-2112-M-001-038-MY2. Z.Y. is supported by an Alexander von Humboldt Fellowship and acknowledges support from the ERC Synergy Grant BlackHoleCam-Imaging the Event Horizon of Black Holes (Grant 610058). S.-J.Y. acknowledges support from the National Research Foundation of Korea to the Centre for Galaxy Evolution Research (No. 2010-0027910), from the Mid-Career Researcher Program (No. 2015-008049) through the National Research Foundation (NRF) of Korea, and from the Yonsei University Future-leading Research Initiative of 20142015. This research has made use of NASAs Astrophysics Data System.

Publisher Copyright:
© 2016. The American Astronomical Society. All rights reserved.

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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