Event Horizon Telescope observations of the jet launching and collimation in Centaurus A
Authors: Janssen Michael , Falcke Heino , Kadler Matthias , Ros Eduardo , Wielgus Maciek , Akiyama Kazunori , Baloković Mislav , Blackburn Lindy , Bouman Katherine L. , Chael Andrew , Chan Chi-kwan , Chatterjee Koushik , Davelaar Jordy , Edwards Philip G. , Fromm Christian M. , Gómez José L. , Goddi Ciriaco , Issaoun Sara , Johnson Michael D. , Kim Junhan , Koay Jun Yi , Krichbaum Thomas P. , Liu Jun , Liuzzo Elisabetta , Markoff Sera , Markowitz Alex , Marrone Daniel P. , Mizuno Yosuke , Müller Cornelia , Ni Chunchong , Pesce Dominic W. , Ramakrishnan Venkatessh , Roelofs Freek , Rygl Kazi L. J. , van Bemmel Ilse ,   The Event Horizon Telescope Collaboration, Alberdi Antxon , Alef Walter , Algaba Juan Carlos , Anantua Richard , Asada Keiichi , Azulay Rebecca , Baczko Anne-Kathrin , Ball David , Barrett John , Benson Bradford A. , Bintley Dan , Blundell Raymond , Boland Wilfred , Bower Geoffrey C. , Boyce Hope , Bremer Michael , Brinkerink Christiaan D. , Brissenden Roger , Britzen Silke , Broderick Avery E. , Broguiere Dominique , Bronzwaer Thomas , Byun Do-Young , Carlstrom John E. , Chatterjee Shami , Chen Ming-Tang , Chen Yongjun , Chesler Paul M. , Cho Ilje , Christian Pierre , Conway John E. , Cordes James M. , Crawford Thomas M. , Crew Geoffrey B. , Cruz-Osorio Alejandro , Cui Yuzhu , De Laurentis Mariafelicia , Deane Roger , Dempsey Jessica , Desvignes Gregory , Dexter Jason , Doeleman Sheperd S. , Eatough Ralph P. , Farah Joseph , Fish Vincent L. , Fomalont Ed , Ford H. Alyson , Fraga-Encinas Raquel , Friberg Per , Fuentes Antonio , Galison Peter , Gammie Charles F. , García Roberto , Gelles Zachary , Gentaz Olivier , Georgiev Boris , Gold Roman , Gómez-Ruiz Arturo I. , Gu Minfeng , Gurwell Mark , Hada Kazuhiro , Haggard Daryl , Hecht Michael H. , Hesper Ronald , Himwich Elizabeth , Ho Luis C. , Ho Paul , Honma Mareki , Huang Chih-Wei L. , Huang Lei , Hughes David H. , Ikeda Shiro , Inoue Makoto , James David J. , Jannuzi Buell T. , Jeter Britton , Jiang Wu , Jimenez-Rosales Alejandra , Jorstad Svetlana , Jung Taehyun , Karami Mansour , Karuppusamy Ramesh , Kawashima Tomohisa , Keating Garrett K. , Kettenis Mark , Kim Dong-Jin , Kim Jae-Young , Kim Jongsoo , Kino Motoki , Kofuji Yutaro , Koyama Shoko , Kramer Michael , Kramer Carsten , Kuo Cheng-Yu , Lauer Tod R. , Lee Sang-Sung , Levis Aviad , Li Yan-Rong , Li Zhiyuan , Lindqvist Michael , Lico Rocco , Lindahl Greg , Liu Kuo , Lo Wen-Ping , Lobanov Andrei P. , Loinard Laurent , Lonsdale Colin , Lu Ru-Sen , MacDonald Nicholas R. , Mao Jirong , Marchili Nicola , Marscher Alan P. , Martí-Vidal Iván , Matsushita Satoki , Matthews Lynn D. , Medeiros Lia , Menten Karl M. , Mizuno Izumi , Moran James M. , Moriyama Kotaro , Moscibrodzka Monika , Musoke Gibwa , Mejías Alejandro Mus , Nagai Hiroshi , Nagar Neil M. , Nakamura Masanori , Narayan Ramesh , Narayanan Gopal , Natarajan Iniyan , Nathanail Antonios , Neilsen Joey , Neri Roberto , Noutsos Aristeidis , Nowak Michael A. , Okino Hiroki , Olivares Héctor , Ortiz-León Gisela N. , Oyama Tomoaki , Özel Feryal , Palumbo Daniel C. M. , Park Jongho , Patel Nimesh , Pen Ue-Li , Piétu Vincent , Plambeck Richard , PopStefanija Aleksandar , Porth Oliver , Pötzl Felix M. , Prather Ben , Preciado-López Jorge A. , Psaltis Dimitrios , Pu Hung-Yi , Rao Ramprasad , Rawlings Mark G. , Raymond Alexander W. , Rezzolla Luciano , Ricarte Angelo , Ripperda Bart , Rogers Alan , Rose Mel , Roshanineshat Arash , Rottmann Helge , Roy Alan L. , Ruszczyk Chet , Sánchez Salvador , Sánchez-Arguelles David , Sasada Mahito , Savolainen Tuomas , Schloerb F. Peter , Schuster Karl-Friedrich , Shao Lijing , Shen Zhiqiang , Small Des , Sohn Bong Won , SooHoo Jason , Sun He , Tazaki Fumie , Tetarenko Alexandra J. , Tiede Paul , Tilanus Remo P. J. , Titus Michael , Torne Pablo , Trent Tyler , Traianou Efthalia , Trippe Sascha , van Bemmel Ilse , van Langevelde Huib Jan , van Rossum Daniel R. , Wagner Jan , Ward-Thompson Derek , Wardle John , Weintroub Jonathan , Wex Norbert , Wharton Robert , Wong George N. , Wu Qingwen , Yoon Doosoo , Young André , Young Ken , Younsi Ziri , Yuan Feng , Yuan Ye-Fei , Zensus J. Anton , Zhao Guang-Yao , Zhao Shan-Shan 
Published: July 2021

Very-long-baseline interferometry (VLBI) observations of active galactic nuclei at millimetre wavelengths have the power to reveal the launching and initial collimation region of extragalactic radio jets, down to 10–100 gravitational radii (rg ≡ GM/c2) scales in nearby sources1. Centaurus A is the closest radio-loud source to Earth2. It bridges the gap in mass and accretion rate between the supermassive black holes (SMBHs) in Messier 87 and our Galactic Centre. A large southern declination of −43° has, however, prevented VLBI imaging of Centaurus A below a wavelength of 1 cm thus far. Here we show the millimetre VLBI image of the source, which we obtained with the Event Horizon Telescope at 228 GHz. Compared with previous observations3, we image the jet of Centaurus A at a tenfold higher frequency and sixteen times sharper resolution and thereby probe sub-lightday structures. We reveal a highly collimated, asymmetrically edge-brightened jet as well as the fainter counterjet. We find that the source structure of Centaurus A resembles the jet in Messier 87 on ~500 rg scales remarkably well. Furthermore, we identify the location of Centaurus A’s SMBH with respect to its resolved jet core at a wavelength of 1.3 mm and conclude that the source’s event horizon shadow4 should be visible at terahertz frequencies. This location further supports the universal scale invariance of black holes over a wide range of masses5,6.