Gravitational Test beyond the First Post-Newtonian Order with the Shadow of the M87 Black Hole
Dimitrios Psaltis, Lia Medeiros, Pierre Christian, Feryal Özel, Kazunori Akiyama, Antxon Alberdi, W. Alef, Keiichi Asada, Rebecca Azulay, David Ball, Mislav Baloković, John Barrett, Dan Bintley, Lindy Blackburn, W. Boland, Geoffrey C. Bower, Michael Bremer, Christiaan D. Brinkerink, Roger Brissenden, S. Britzen, Dominique Broguière, Thomas Bronzwaer, Do‐Young Byun, J. E. Carlstrom, Andrew Chael, Chi‐kwan Chan, Shami Chatterjee, Koushik Chatterjee, Ming‐Tang Chen, Xiaopeng Cheng, Ilje Cho, J. E. Conway, J. M. Cordes, G. Crew, Yuzhu Cui, Jordy Davelaar, Mariafelicia De Laurentis, Roger Deane, Jessica Dempsey, G. Desvignes, Jason Dexter, Ralph P. Eatough, H. Falcke, Vincent L. Fish, Ed Fomalont, Raquel Fraga-Encinas, Per Friberg, Christian M. Fromm, Charles F. Gammie, Roberto García, Olivier Gentaz, C. Goddi, José L. Gómez, Minfeng Gu, Mark Gurwell, Kazuhiro Hada, Ronald Hesper, Luis C. Ho, Paul T. P. Ho, Mareki Honma, Chih-Wei L. Huang, Lei Huang, D. H. Hughes, Makoto Inoue, Sara Issaoun, D. J. James, Buell T. Jannuzi, Michaël Janssen, Wu Jiang, Alejandra Jiménez-Rosales, Michael D. Johnson, Svetlana G. Jorstad, Taehyun Jung, Mansour Karami, R. Karuppusamy, Tomohisa Kawashima, Garrett K. Keating, Mark Kettenis, Jae-Young Kim, Junhan Kim, Jongsoo Kim, Motoki Kino, Jun Yi Koay, Patrick M. Koch, Shoko Koyama, M. Krämer, C. Krämer, T. P. Krichbaum, Cheng‐Yu Kuo, Tod R. Lauer, Sang-Sung Lee, Yanrong Li, Zhiyuan Li, M. Lindqvist, Rocco Lico, Jun Liu, Kuo Liu, Elisabetta Liuzzo, Wen-Ping Lo, A. P. Lobanov
Abstract
We present measurements of the properties of the central radio source in M87 using Event Horizon Telescope data obtained during the 2017 campaign. We develop and fit geometric crescent models (asymmetric rings with interior brightness depressions) using two independent sampling algorithms that consider distinct representations of the visibility data. We show that the crescent family of models is statistically preferred over other comparably complex geometric models that we explore. We calibrate the geometric model parameters using general relativistic magnetohydrodynamic (GRMHD) models of the emission region and estimate physical properties of the source. We further fit images generated from GRMHD models directly to the data. We compare the derived emission region and black hole parameters from these analyses with those recovered from reconstructed images. There is a remarkable consistency among all methods and data sets. We find that >50% of the total flux at arcsecond scales comes from near the horizon, and that the emission is dramatically suppressed interior to this region by a factor >10, providing direct evidence of the predicted shadow of a black hole. Across all methods, we measure a crescent diameter of 423 as and constrain its fractional width to be <0.5. Associating the crescent feature with the emission surrounding the black hole shadow, we infer an angular gravitational radius of GM/Dc 2 =3.80.4 as. Folding in a distance measurement of -+ 16.8 Mpc 0.7 0.8 gives a black hole mass of = | | M M 6.5 0.2 0.7 10 stat sys 9