Black holes, these fascinating and mysterious objects in the universe, have just revealed a little more of their secrets thanks toEvent Horizon Telescope (EHT). This global network of telescopes has managed to take the sharpest image of a black hole ever taken from Earth. This major advance, announced on August 27, 2024opens up new perspectives for us to better understand these cosmic phenomena.
How innovative technology is changing the game in astronomy
The EHT is not just another telescope. It is a global ensemble that uses a cutting-edge technique called very long baseline interferometry (VLBI)thus creating a virtual telescope as large as our planet. By bringing together data from several telescopes scattered across the globe, the EHT achieves breathtaking resolution.
Among the instruments involved in this observation are the Atacama Large Millimeter/submillimeter Array (ALMA)the Atacama Pathfinder EXperiment (APEX)l’ANGERthe NOrthern Extended Millimeter Array (NOEMA)the Submillimeter Array (SMA) and the Greenland Telescope. Thanks to these powerful tools, we were able to obtain incredible resolution of 19 microarcsecondesoffering images of unprecedented clarity.
What are the promising discoveries from high-frequency observations?
During this recent observation campaign, the EHT captured light coming from distant galaxies at an impressive frequency of 345 GHzwith a wavelength of 0.87 mm. This is the first time that such a frequency has been used with the VLBI technique to observe a black hole. Before that, we stayed on 230 GHz, which limited the clarity of the images.
Alexander Raymond, co-author of a study published in theAstronomical Journalexplains: “With the EHT, our first images showed black holes by detecting radio waves at 230 GHz. But even there, the light ring was blurry because we were reaching the limits of what we could do in terms of sharpness.” With the new observations at 345 GHz, he hopes to see “clearer and more detailed images”.
What technical challenges were overcome to go even further?
Observing at such a high frequency poses quite a few technical problems. Water vapor in the atmosphere greatly absorbs 345 GHz signals, making it difficult to capture them from Earth. To get around this major obstacle, EHT has benefited from notable technological improvements such as a wider bandwidth increasing its sensitivity.
-Patel says: “Now that we have high-bandwidth systems capable of processing and capturing larger portions of the radio spectrum, we are finally starting to overcome some basic sensitivity concerns.” Careful planning was also essential to choose times when the weather was ideal at all observation sites.
The future looks exciting for the study of black holes
The future seems full of hope for the EHT and its bold projects. The project ngEHT plans to further expand this network by adding new antennas and improving existing ones. The ultimate idea? Not only produce still images but also create high fidelity movies of black holes to follow their dynamics in real time.
This progress goes far beyond a simple technical feat; it could reveal unsuspected properties of black holes and enrich our vision of the cosmos. As researchers continue their careful exploration of these celestial mysteries with ever greater precision, each new discovery brings us one step closer to the secrets buried at the edges of our universe.
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