Astronomers Capture First Image of a

Black Hole


RadioNet infrastructures contribute to paradigm-shifting observations of the gargantuan black hole at the heart of distant galaxy Messier 87

The Event Horizon Telescope (EHT) — a planet-scale array of eight ground-based radio telescopes forged through international collaboration — was designed to capture images of a black hole. Today, in coordinated press conferences across the globe, EHT researchers reveal that they have succeeded, unveiling the first direct visual evidence of a supermassive black hole and its shadow.

Planet-Forming Disks Workshop


This breakthrough was announced today in a series of six papers published in a special issue of Astrophysical Journal Letters. The image reveals the black hole at the centre of Messier 87 [1], a massive galaxy in the nearby Virgo galaxy cluster. This black hole resides 55 million light-years from Earth and has a mass 6.5-billion times that of the Sun [2].

The EHT links telescopes around the globe to form an Earth-sized virtual telescope with unprecedented sensitivity and resolution [3]. The EHT is the result of years of international collaboration, and offers scientists a new way to study the most extreme objects in the Universe predicted by Einstein’s general relativity during the centennial year of the historic experiment that first confirmed the theory [4].

We feel excited to finally see the long awaited spectacular first view of a black hole, for which scientists and engineers have worked for decades”, says EHT Board Chair and RadioNet coordinator J. Anton Zensus, Director at the Max Planck Institute for Radio Astronomy in Bonn. Karl Schuster, director of IRAM and a member of RadioNet and EHT Boards, pointed out that “the IRAM 30-m telescope, due to its location and sensitivity is absolutely critical for the results obtained. High-resolution radio astronomical observation is a unique method to analyse black holes.”

Black holes are extremely compressed cosmic objects, containing incredible amounts of mass within a tiny region. The presence of these objects affects their environment in extreme ways, warping spacetime and super-heating any surrounding material.

Multiple independent EHT observations and imaging methods have revealed a ring-like structure with a dark central region — the black hole’s shadow.

"Once we were sure we had imaged the shadow, we could compare our observations to extensive computer models that include the physics of warped space, superheated matter and strong magnetic fields. Many of the features of the observed image match our theoretical predictions surprisingly well," remarks Paul T.P. Ho, EHT Board member and Director of the East Asian Observatory [5]. "This makes us confident about the interpretation of our observations, including our estimation of the black hole’s mass."

Creating the EHT was a formidable challenge, which required upgrading, and connecting a worldwide network of eight pre-existing telescopes deployed at a variety of challenging high-altitude sites. These locations included volcanoes in Hawaii and Mexico, mountains in Arizona and the Spanish Sierra Nevada, the Chilean Atacama Desert, and Antarctica.

The EHT observations use a technique called very-long-baseline interferometry (VLBI), which synchronises telescope facilities around the world and exploits the rotation of our planet to form one huge, Earth-size telescope observing at a wavelength of 1.3mm. VLBI allows the EHT to achieve an angular resolution of 20 micro-arcseconds — enough to read a newspaper in New York from a sidewalk café in Paris [6].

The telescopes contributing to this result were ALMA, APEX, the IRAM 30-meter telescope, the James Clerk Maxwell Telescope, the Large Millimeter Telescope Alfonso Serrano, the Submillimeter Array, the Submillimeter Telescope, and the South Pole Telescope [7]. The data analysis necessary to transform the raw data into the final image was conducted by highly specialised supercomputers hosted by the Max Planck Institute for Radio Astronomy and MIT Haystack Observatory.

© Photo credits: ALMA - ESO / C. Malin; SMA - Shelbi Hostler; SPT - Jeff McMahon; SMT - David Harvey; PV - IRAM; JCMT - JCMT/JAC; LMT - Gopal Narayanan; APEX - APEX.

The construction of the EHT and the observations announced today represent the culmination of decades of observational, technical, and theoretical work. This example of global teamwork required close collaboration by researchers from around the world. Thirteen partner institutions worked together to create the EHT, using both pre-existing infrastructure and support from a variety of agencies. Key funding was provided by the US National Science Foundation (NSF), the EU's European Research Council (ERC), and funding agencies in East Asia.

RadioNet and thus the European Commission contributed to the success of the EHT project. "It is great to see that our investment in European millimetre radio astronomy, the technological upgrade of telescopes, the training of users and especially the free access to the infrastructures, succeeded in such an excellent result" said Zensus.

Commissioner Carlos Moedas, responsible for Research, Science, and Innovation, said: “Fiction often inspires science and black holes have long fuelled our dreams and curiosity. Today, thanks to the amazing contribution of European scientists, the existence of black holes is no longer just a theoretical concept. This amazing discovery proves again how working together with partners around the world can lead to achieving the unthinkable and moving the horizons of our knowledge.”

"We have achieved something presumed to be impossible just a generation ago," concluded Doeleman. "Breakthroughs in technology and the completion of new radio telescopes over the past decade enabled our team to assemble this new instrument — designed to see the unseeable."



[1] The shadow of a black hole is the closest we can come to an image of the black hole itself, a completely dark object from which light cannot escape. The black hole’s boundary — the event horizon from which the EHT takes its name — is around five times smaller than the shadow it casts and measures just under 40 billion km across.

[2] Supermassive black holes are relatively tiny astronomical objects — which has made them impossible to directly observe until now. As a black hole’s size is proportional to its mass, the more massive a black hole, the larger the shadow. Thanks to its enormous mass and relative proximity, M87’s black hole was predicted to be one of the largest viewable from Earth — making it a perfect target for the EHT.

[3] Although the telescopes are not physically connected, they are able to synchronize their recorded data with atomic clocks — hydrogen masers — which precisely time their observations. These observations were collected at a wavelength of 1.3 mm during a 2017 global campaign. Each telescope of the EHT produced enormous amounts of data – roughly 350 terabytes per day – which was stored on high-performance helium-filled hard drives. These data were flown to highly specialised supercomputers — known as correlators — at the Max Planck Institute for Radio Astronomy and MIT Haystack Observatory to be painstakingly combined into an image.

[4] 100 years ago, two expeditions set out for the island of Príncipe off the coast of Africa and Sobra in Brazil to observe the 1919 solar eclipse, with the goal of testing general relativity by seeing if starlight would be bent around the limb of the sun, as predicted by Einstein. In an echo of those observations, the EHT has sent team members to some of the world's highest and isolated radio facilities to once again test our understanding of gravity.

[5] The East Asian Observatory (EAO) partner on the EHT project represents the participation of many regions in Asia, including China, Japan, Korea, Taiwan, Vietnam, Thailand, Malaysia, India and Indonesia.

[6] Future EHT observations will see substantially increased sensitivity with the participation of the IRAM NOEMA Observatory, the Greenland Telescope and the Kitt Peak Telescope.

[7] ALMA is a partnership of the European Southern Observatory (ESO; Europe, representing its member states), the U.S. National Science Foundation (NSF), and the National Institutes of Natural Sciences (NINS) of Japan, together with the National Research Council (Canada), the Ministry of Science and Technology (MOST; Taiwan), Academia Sinica Institute of Astronomy and Astrophysics (ASIAA; Taiwan), and Korea Astronomy and Space Science Institute (KASI; Republic of Korea), in cooperation with the Republic of Chile. APEX is operated by ESO, the 30-meter telescope is operated by IRAM (the IRAM Partner Organizations are MPG (Germany), CNRS (France) and IGN (Spain)), the James Clerk Maxwell Telescope is operated by the EAO, the Large Millimeter Telescope Alfonso Serrano is operated by INAOE and UMass, the Submillimeter Array is operated by SAO and ASIAA and the Submillimeter Telescope is operated by the Arizona Radio Observatory (ARO). The South Pole Telescope is operated by the University of Chicago with specialized EHT instrumentation provided by the University of Arizona.


More Information

This research was presented in a series of six papers published today in a special issue of Astrophysical Journal Letters.

The EHT collaboration involves more than 200 researchers from Africa, Asia, Europe, North and South America. The international collaboration is working to capture the first-ever image of a black hole by creating a virtual Earth-sized telescope. Supported by considerable international investment, the EHT links existing telescopes using novel systems — creating a fundamentally new instrument with the highest angular resolving power that has yet been achieved.

The individual telescopes involved are; ALMA, APEX, the IRAM 30-meter Telescope, the IRAM NOEMA Observatory, the James Clerk Maxwell Telescope (JCMT), the Large Millimeter Telescope Alfonso Serrano (LMT), the Submillimeter Array (SMA), the Submillimeter Telescope (SMT), the South Pole Telescope (SPT), the Kitt Peak Telescope, and the Greenland Telescope (GLT).

The EHT consortium consists of 13 stakeholder institutes; the Academia Sinica Institute of Astronomy and Astrophysics, the University of Arizona, the University of Chicago, the East Asian Observatory, Goethe-Universitaet Frankfurt, Institut de Radioastronomie Millimétrique, Large Millimeter Telescope, Max Planck Institute for Radio Astronomy, MIT Haystack Observatory, National Astronomical Observatory of Japan, Perimeter Institute for Theoretical Physics, Radboud University and the Smithsonian Astrophysical Observatory.

ALMA, APEX, the IRAM 30-meter Telescope, the IRAM NOEMA Observatory (which will join the EHT network soon) have received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 730562 [RadioNet].


EHT Press Conference - 10 April 2019 - 3.00 CEST - Brussels - Lifestream



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RadioNet has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 730562, and contribution from the partner organisations