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The European Southern Observatory (ESO) and the Event Horizon Telescope (EHT) project are holding a global press conference on 12 May to unveil new discoveries about the center of the Milky Way. This international collaboration between radio telescopes and Event Horizon Telescope observatories was primarily aimed at taking the first image of a black hole. This has been done since 2019, when astronomers released the first live image ever of the event horizon of a black hole in the giant elliptical galaxy M87. Similarly, at the press conference scheduled for May 12, a historic revelation is expected regarding our galaxy’s central black hole, Sagittarius A *.
EHT is a virtual telescope (a network of telescopes) with a diameter of 10,000 km. The larger a telescope, the more details it can capture. However, it is not a unique telescope! It would certainly risk collapsing under its own weight … The Event Horizon telescope covers a large part of the globe thanks to the combination of several observatories spread across the planet. It thus brings together the 30-meter telescope from IRAM (International Millimeter Radioastronomy Institute) in Europe, the ALMA radio telescope in Chile (co-controlled by Europe, the United States and Japan) and structures in the United States. Hawaii and Antarctica.
Despite this rollout of technologies, the image of a “real” black hole has still not reached us, even though the EHT teams revealed a quality image in 2019. In fact, this type of astronomical object has the main property of being so massive that nothing can escape , not even light. What the researchers have been trying to observe for years is what is around the black hole, the “growth disk”. It is matter and gas that orbit the core of the object at very high speeds, heated to extreme temperatures. Of course, they end up being devoured by the black hole.
Given that the project’s scientists are holding simultaneous press conferences around the world on May 12, we can conclude that their announcement will most likely be groundbreaking and may well relate to the first image of the supermassive black hole in the center of the planet. . The Milky Way, called Sagittarius A *.
For EHT, observation of Sagittarius A * and M87 * requires good meteorological conditions at the eight sites simultaneously. Sagittarius A * was the first of the project’s two goals. The object is located 26,000 light-years from Earth, in the heart of our galaxy. Its mass is equivalent to 4.3 million times that of the Sun, which is relatively low for a supermassive black hole. The second target is the black hole in the galaxy M87, which is much larger and located much further away.
Despite this, it was the M87 that gave the first results that could be exploited. In fact, Sgr A * is hidden by a cloud of dust and gas, making it particularly difficult to study. The M87’s image looks a bit like a fuzzy orange patch. In the center is the “shadow” of the black hole that appears as an opaque area. So we do not actually see the black hole, as its gravity prevents any potentially detectable radiation from escaping. Experts compare taking a direct image of the M87 * with observing an object 1 millimeter in size at a distance of 13,000 kilometers.
Note that the data produced by this observation network is significant, so much so that to move all the datasets, it was done by the whole box of hard drives. In addition, not all data were available simultaneously. The Antarctic telescope is actually isolated half the year. Either way, we will have to wait until May 12 to find out what EHT has observed regarding Sgr A * and what the researchers have concluded.
Multiple distribution channels for a groundbreaking message
However, ESO’s press release promises something “revolutionary”. This is the term already used to announce the first live image of a black hole in 2019. The conference will be broadcast online on ESO’s website and on ESO’s YouTube channel on 12 May 2022 at. 15:00 CEST (3: 22.00 French time). At the same time, press conferences will be held around the world, including Washington DC, Santiago de Chile, Mexico City, Tokyo and Taipei. The press releases will contain important audiovisual material, enough to make us dream!
In the case of ESO, the conference will be held at the headquarters in Germany. The Director-General of ESO will deliver the keynote address. Huib Jan van Langevelde, EHT Project Director, and Anton Zensus, Founding Chairman of the EHT Collaboration Council, will also give keynote speeches. A panel of EHT researchers will explain the result and answer questions. The lectures will be followed by a YouTube event with several experts in EHT astronomers, for the public, as a question-and-answer session.