The European Southern Observatory (ESO) and the Event Horizon Telescope (EHT) project will hold a global press conference on May 12 to reveal new discoveries about the center of the Milky Way. This international collaboration of radio telescopes and Event Horizon Telescope observatories aimed primarily to capture the first image of a black hole. It’s been done since 2019, when astronomers released the first-ever direct image of a black hole’s event horizon. galaxy giant elliptical M87. Similarly, at the press conference scheduled for May 12, a historic revelation is expected to be made regarding the central black hole of our galaxy, Sagittarius A*.
The EHT is a virtual telescope (a network of telescopes) with a diameter of 10,000 km. The larger a telescope, the more detail it can capture. However, it is not a unique telescope! Indeed, it would then 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 of IRAM (International Millimeter Radioastronomy Institute) in Europe, the ALMA radio telescope in Chile (co-managed by Europe, the United States and Japan) as well as structures in the United States. States, Hawaii, and Antarctica.
Despite this deployment of technologies, the photo of a “real” black hole has still not reached us, even if the EHT teams have unveiled a quality image in 2019. Indeed, this type of astronomical object has the main property of being so massive that nothing can escape, not even light. What scientists have been trying to observe for years is what is around the black hole, the “accretion disk”. It is matter and gas orbiting around the core of the object at very high speed, heated to extreme temperatures. Of course, they end up being devoured by the black hole.
Given that the project scientists are holding simultaneous press conferences around the world next May 12, we can infer that their announcement will most likely be groundbreaking and may well concern the first image of the supermassive black hole at the center of the planet. Milky Way, named Sagittarius A*.
Two targets
For the EHT, the observation of Sagittarius A* and M87* require good weather conditions at all eight sites simultaneously. Sagittarius A* was the first of the project’s two targets. The object is located at 26,000 light years of Earth, at 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 of the galaxy M87, which is much larger and located much further away.
Despite this, it was M87 that provided the first exploitable results. Indeed, Sgr A* is obscured by a cloud of dust and gas, making it particularly difficult to study. M87’s image looks a bit like a fuzzy orange patch. In the middle is the “shadow” of the black hole, appearing as an opaque area. So we don’t actually see the black hole, since its gravity prevents any potentially detectable radiation from escaping. Experts compare taking a direct image of M87* to observing an object 1 millimeter in size at a distance of 13,000 kilometers.
Note that the data produced by this observation network is considerable, so much so that to move all the data sets, it was done by whole box of hard disks. In addition, not all data was accessible simultaneously. Indeed, the Antarctic telescope is isolated half the year. Either way, we’ll have to wait until May 12 to find out what the EHT has observed regarding Sgr A* and what the scientists have concluded.
Multiple distribution channels for a groundbreaking announcement
However, the ESO press release promises something “revolutionary”. This is the term that was already used to announce the first direct image of a black hole in 2019. The conference will be broadcast online on the ESO website and on the ESO YouTube channel on 12 May 2022 at 3:00 p.m. CEST (3:00 p.m. French time). Simultaneous press conferences will be held around the world, including Washington DC, Santiago de Chile, Mexico City, Tokyo and Taipei. The press releases will include important audiovisual material, enough to leave us dreaming!
As far as ESO is concerned, 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 deliver keynote addresses. A panel of EHT researchers will explain the result and answer questions. The lectures will be followed by a YouTube event with several EHT expert astronomers, for the public, like a question-and-answer session.