Story Behind and details of the First ever black hole image

First M87 Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole –
The Astrophysical Journal Letters

April 10, 2019, Astrophysical Journal Letters published a groundbreaking article titled “First M87 Event Horizon Telescope Results. I. The Shadow of the Supermassive Black Hole“. This article published the first ever black hole image. It was captured by the Event Horizon Telescope (EHT), a network of eight linked telescopes.

Abstract of the published paper

When surrounded by a transparent emission region, black holes are expected to reveal a dark shadow caused by gravitational light bending and photon capture at the event horizon. To image and study this phenomenon, we have assembled the Event Horizon Telescope, a global very long baseline interferometry array observing at a wavelength of 1.3 mm. This allows us to reconstruct event-horizon-scale images of the supermassive black hole candidate in the center of the giant elliptical galaxy M87. We have resolved the central compact radio source as an asymmetric bright emission ring with a diameter of 42 ± 3 μas, which is circular and encompasses a central depression in brightness with a flux ratio gsim10:1. The emission ring is recovered using different calibration and imaging schemes, with its diameter and width remaining stable over four different observations carried out in different days. Overall, the observed image is consistent with expectations for the shadow of a Kerr black hole as predicted by general relativity. The asymmetry in brightness in the ring can be explained in terms of relativistic beaming of the emission from a plasma rotating close to the speed of light around a black hole. We compare our images to an extensive library of ray-traced general-relativistic magnetohydrodynamic simulations of black holes and derive a central mass of M = (6.5 ± 0.7) × 10^9 M_⊙. Our radio-wave observations thus provide powerful evidence for the presence of supermassive black holes in centers of galaxies and as the central engines of active galactic nuclei. They also present a new tool to explore gravity in its most extreme limit and on a mass scale that was so far not accessible.


The Black Hole measures 40 billion km across which is 3 million times the size of the Earth and has been described by scientists as “a monster”. The black hole is 500 million trillion km away and was photographed by a network of eight telescopes across the world.

The image shows an intensely bright “ring of fire”, as Prof Falcke describes it, surrounding a perfectly circular dark hole. The bright halo is caused by superheated gas falling into the hole. The light is brighter than all the billions of other stars in the galaxy combined – which is why it can be seen at such distance from Earth. The edge of the dark circle at the centre is the point at which the gas enters the black hole, which is an object that has such a large gravitational pull, not even light can escape.

What is a black hole?

A black hole is a region of space from which nothing, not even light, can escape. Despite the name, they are not empty but instead consist of a huge amount of matter packed densely into a small area, giving it an immense gravitational pull. There is a region of space beyond the black hole called the event horizon. This is a “point of no return”, beyond which it is impossible to escape the gravitational effects of the black hole.

Prof Falcke had the idea for the project when he was a PhD student in 1993. At the time, no-one thought it was possible. But he was the first to realise that a certain type of radio emission would be generated close to and all around the black hole, which would be powerful enough to be detected by telescopes on Earth. He also recalled reading a scientific paper from 1973 that suggested that because of their enormous gravity, black holes appear 2.5 times larger than they actually are. These two factors suddenly made the seemingly impossible, possible. After arguing his case for 20 years, Prof Falcke persuaded the European Research Council to fund the project. The National Science Foundation and agencies in East Asia then joined in to bankroll the project to the tune of more than £40m.

Eight stations of the EHT 2017 campaign over six geographic locations as viewed from the equatorial plane.
Eight stations of the EHT 2017 campaign over six geographic locations as viewed from the equatorial plane.

No single telescope is powerful enough to image the black hole. So, in the biggest experiment of its kind, Prof Sheperd Doeleman of the Harvard-Smithsonian Centre for Astrophysics led a project to set up a network of eight linked telescopes. Together, they form the Event Horizon Telescope and can be thought of as a planet-sized array of dishes. Each is located high up at a variety of exotic sites, including on volcanoes in Hawaii and Mexico, mountains in Arizona and the Spanish Sierra Nevada, in the Atacama Desert of Chile, and in Antarctica.

A team of 200 scientists pointed the networked telescopes towards M87 and scanned its heart over a period of 10 days. The information they gathered was too much to be sent across the internet. Instead, the data was stored on hundreds of hard drives that were flown to central processing centres in Boston, US, and Bonn, Germany, to assemble the information. Katie Bouman a PhD student at MIT developed an algorithm that pieced together the data from the EHT. Without her contribution, the project would not have been possible. Prof Doeleman described the achievement as “an extraordinary scientific feat”. “We have achieved something presumed to be impossible just a generation ago,” he said.

“Breakthroughs in technology, connections between the world’s best radio observatories, and innovative algorithms all came together to open an entirely new window on black holes.” The team is also imaging the supermassive black hole at the centre of our own galaxy, the Milky Way. Odd though it may sound, that is harder than getting an image from a distant galaxy 55 million light-years away. This is because, for some unknown reason, the “ring of fire” around the black hole at the heart of the Milky Way is smaller and dimmer.

The full list of authors/researchers involved in this research are listed here

  1. The Event Horizon Telescope Collaboration
  2. Kazunori Akiyama
  3. Antxon Alberdi
  4. Walter Alef
  5. Keiichi Asada
  6. Rebecca Azulay
  7. Anne-Kathrin Baczko
  8. David Ball
  9. Mislav Baloković
  10. John Barrett
  11. Dan Bintley
  12. Lindy Blackburn
  13. Wilfred Boland
  14. Katherine L. Bouman
  15. Geoffrey C. Bower
  16. Michael Bremer
  17. Christiaan D. Brinkerink
  18. Roger Brissenden
  19. Silke Britzen
  20. Avery E. Broderick
  21. Dominique Broguiere
  22. Thomas Bronzwaer
  23. Do-Young Byun
  24. John E. Carlstrom
  25. Andrew Chael
  26. Chi-kwan Chan
  27. Shami Chatterjee
  28. Koushik Chatterjee
  29. Ming-Tang Chen
  30. Yongjun Chen (陈永军)
  31. Ilje Cho
  32. Pierre Christian
  33. John E. Conway
  34. James M. Cordes
  35. Geoffrey B. Crew
  36. Yuzhu Cui
  37. Jordy Davelaar
  38. Mariafelicia De Laurentis
  39. Roger Deane
  40. Jessica Dempsey
  41. Gregory Desvignes
  42. Jason Dexter
  43. Sheperd S. Doeleman
  44. Ralph P. Eatough
  45. Heino Falcke
  46. Vincent L. Fish
  47. Ed Fomalont
  48. Raquel Fraga-Encinas
  49. William T. Freeman
  50. Per Friberg
  51. Christian M. Fromm
  52. José L. Gómez
  53. Peter Galison
  54. Charles F. Gammie
  55. Roberto García
  56. Olivier Gentaz
  57. Boris Georgiev
  58. Ciriaco Goddi
  59. Roman Gold
  60. Minfeng Gu (顾敏峰)
  61. Mark Gurwell
  62. Kazuhiro Hada
  63. Michael H. Hecht
  64. Ronald Hesper
  65. Luis C. Ho (何子山)
  66. Paul Ho
  67. Mareki Honma
  68. Chih-Wei L. Huang
  69. Lei Huang (黄磊)
  70. David H. Hughes
  71. Shiro Ikeda
  72. Makoto Inoue
  73. Sara Issaoun
  74. David J. James
  75. Buell T. Jannuzi
  76. Michael Janssen
  77. Britton Jeter
  78. Wu Jiang (江悟)
  79. Michael D. Johnson
  80. Svetlana Jorstad
  81. Taehyun Jung
  82. Mansour Karami
  83. Ramesh Karuppusamy
  84. Tomohisa Kawashima
  85. Garrett K. Keating
  86. Mark Kettenis
  87. Jae-Young Kim
  88. Junhan Kim
  89. Jongsoo Kim
  90. Motoki Kino
  91. Jun Yi Koay
  92. Patrick M. Koch
  93. Shoko Koyama
  94. Michael Kramer
  95. Carsten Kramer
  96. Thomas P. Krichbaum
  97. Cheng-Yu Kuo
  98. Tod R. Lauer
  99. Sang-Sung Lee
  100. Yan-Rong Li (李彦荣)
  101. Zhiyuan Li (李志远)
  102. Michael Lindqvist
  103. Kuo Liu
  104. Elisabetta Liuzzo
  105. Wen-Ping Lo
  106. Andrei P. Lobanov
  107. Laurent Loinard
  108. Colin Lonsdale
  109. Ru-Sen Lu (路如森)
  110. Nicholas R. MacDonald
  111. Jirong Mao (毛基荣)
  112. Sera Markoff
  113. Daniel P. Marrone
  114. Alan P. Marscher
  115. Iván Martí-Vidal
  116. Satoki Matsushita
  117. Lynn D. Matthews
  118. Lia Medeiros
  119. Karl M. Menten
  120. Yosuke Mizuno
  121. Izumi Mizuno
  122. James M. Moran
  123. Kotaro Moriyama
  124. Monika Moscibrodzka
  125. Cornelia Müller
  126. Hiroshi Nagai
  127. Neil M. Nagar
  128. Masanori Nakamura
  129. Ramesh Narayan
  130. Gopal Narayanan
  131. Iniyan Natarajan
  132. Roberto Neri
  133. Chunchong Ni
  134. Aristeidis Noutsos
  135. Hiroki Okino
  136. Héctor Olivares
  137. Gisela N. Ortiz-León
  138. Tomoaki Oyama
  139. Feryal Özel
  140. Daniel C. M. Palumbo
  141. Nimesh Patel
  142. Ue-Li Pen
  143. Dominic W. Pesce
  144. Vincent Piétu
  145. Richard Plambeck
  146. Aleksandar PopStefanija
  147. Oliver Porth
  148. Ben Prather
  149. Jorge A. Preciado-López
  150. Dimitrios Psaltis
  151. Hung-Yi Pu
  152. Venkatessh Ramakrishnan
  153. Ramprasad Rao
  154. Mark G. Rawlings
  155. Alexander W. Raymond
  156. Luciano Rezzolla
  157. Bart Ripperda
  158. Freek Roelofs
  159. Alan Rogers
  160. Eduardo Ros
  161. Mel Rose
  162. Arash Roshanineshat
  163. Helge Rottmann
  164. Alan L. Roy
  165. Chet Ruszczyk
  166. Benjamin R. Ryan
  167. Kazi L. J. Rygl
  168. Salvador Sánchez
  169. David Sánchez-Arguelles
  170. Mahito Sasada
  171. Tuomas Savolainen
  172. F. Peter Schloerb
  173. Karl-Friedrich Schuster
  174. Lijing Shao
  175. Zhiqiang Shen (沈志强)
  176. Des Small
  177. Bong Won Sohn
  178. Jason SooHoo
  179. Fumie Tazaki
  180. Paul Tiede
  181. Remo P. J. Tilanus
  182. Michael Titus
  183. Kenji Toma
  184. Pablo Torne
  185. Tyler Trent
  186. Sascha Trippe
  187. Shuichiro Tsuda
  188. Ilse van Bemmel
  189. Huib Jan van Langevelde
  190. Daniel R. van Rossum
  191. Jan Wagner
  192. John Wardle
  193. Jonathan Weintroub
  194. Norbert Wex
  195. Robert Wharton
  196. Maciek Wielgus
  197. George N. Wong
  198. Qingwen Wu (吴庆文)
  199. Ken Young
  200. André Young
  201. Ziri Younsi
  202. Feng Yuan (袁峰)
  203. Ye-Fei Yuan (袁业飞)
  204. J. Anton Zensus
  205. Guangyao Zhao
  206. Shan-Shan Zhao
  207. Ziyan Zhu
  208. Juan-Carlos Algaba
  209. Alexander Allardi
  210. Rodrigo Amestica
  211. Jadyn Anczarski
  212. Uwe Bach
  213. Frederick K. Baganoff
  214. Christopher Beaudoin
  215. Bradford A. Benson
  216. Ryan Berthold
  217. Jay M. Blanchard
  218. Ray Blundell
  219. Sandra Bustamente
  220. Roger Cappallo
  221. Edgar Castillo-Domínguez
  222. Chih-Cheng Chang
  223. Shu-Hao Chang
  224. Song-Chu Chang
  225. Chung-Chen Chen
  226. Ryan Chilson
  227. Tim C. Chuter
  228. Rodrigo Córdova Rosado
  229. Iain M. Coulson
  230. Thomas M. Crawford
  231. Joseph Crowley
  232. John David
  233. Mark Derome
  234. Matthew Dexter
  235. Sven Dornbusch
  236. Kevin A. Dudevoir
  237. Sergio A. Dzib
  238. Andreas Eckart
  239. Chris Eckert
  240. Neal R. Erickson
  241. Wendeline B. Everett
  242. Aaron Faber
  243. Joseph R. Farah
  244. Vernon Fath
  245. Thomas W. Folkers
  246. David C. Forbes
  247. Robert Freund
  248. Arturo I. Gómez-Ruiz
  249. David M. Gale
  250. Feng Gao
  251. Gertie Geertsema
  252. David A. Graham
  253. Christopher H. Greer
  254. Ronald Grosslein
  255. Frédéric Gueth
  256. Daryl Haggard
  257. Nils W. Halverson
  258. Chih-Chiang Han
  259. Kuo-Chang Han
  260. Jinchi Hao
  261. Yutaka Hasegawa
  262. Jason W. Henning
  263. Antonio Hernández-Gómez
  264. Rubén Herrero-Illana
  265. Stefan Heyminck
  266. Akihiko Hirota
  267. James Hoge
  268. Yau-De Huang
  269. C. M. Violette
  270. Impellizzeri
  271. Homin Jiang
  272. Atish Kamble
  273. Ryan Keisler
  274. Kimihiro Kimura
  275. Yusuke Kono
  276. Derek Kubo
  277. John Kuroda
  278. Richard Lacasse
  279. Robert A. Laing
  280. Erik M. Leitch
  281. Chao-Te Li
  282. Lupin C.-C. Lin
  283. Ching-Tang Liu
  284. Kuan-Yu Liu
  285. Li-Ming Lu
  286. Ralph G. Marson
  287. Pierre L. Martin-Cocher
  288. Kyle D. Massingill
  289. Callie Matulonis
  290. Martin P. McColl
  291. Stephen R. McWhirter
  292. Hugo Messias
  293. Zheng
  294. Meyer-Zhao
  295. Daniel Michalik
  296. Alfredo
  297. Montaña
  298. William
  299. Montgomerie
  300. Matias Mora-Klein
  301. Dirk Muders
  302. Andrew Nadolski
  303. Santiago Navarro
  304. Joseph Neilsen
  305. Chi H. Nguyen
  306. Hiroaki Nishioka
  307. Timothy Norton
  308. Michael A. Nowak
  309. George Nystrom
  310. Hideo Ogawa
  311. Peter Oshiro
  312. Tomoaki Oyama
  313. Harriet Parsons
  314. Scott N. Paine
  315. Juan Peñalver
  316. Neil M. Phillips
  317. Michael Poirier
  318. Nicolas Pradel
  319. Rurik A. Primiani
  320. Philippe A. Raffin
  321. Alexandra S. Rahlin
  322. George Reiland
  323. Christopher Risacher
  324. Ignacio Ruiz
  325. Alejandro F. Sáez-Madaín
  326. Remi Sassella
  327. Pim Schellart
  328. Paul Shaw
  329. Kevin M. Silva
  330. Hotaka Shiokawa
  331. David R. Smith
  332. William Snow
  333. Kamal Souccar
  334. Don Sousa
  335. T. K. Sridharan
  336. Ranjani Srinivasan
  337. William Stahm
  338. Anthony A. Stark
  339. Kyle Story
  340. Sjoerd T. Timmer
  341. Laura Vertatschitsch
  342. Craig Walther Ta-Shun Wei
  343. Nathan Whitehorn
  344. Alan R. Whitney
  345. David P. Woody
  346. Jan G. A. Wouterloot
  347. Melvin Wright
  348. Paul Yamaguchi
  349. Chen-Yu Yu
  350. Milagros Zeballos
  351. Shuo Zhang and
  352. Lucy Ziurys
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Author and Assistant Professor in Finance, Ardent fan of Arsenal FC. Always believe "The only good is knowledge and the only evil is ignorance - Socrates"
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