The Event Horizon Telescope (EHT) has made the highest-resolution observations ever obtained from the Earth’s surface, which will in the future allow for images of black holes that are 50% more detailed than before.
The EHT has conducted test observations using the IRAM Observatory (Granada) and the Atacama Large Millimeter/submillimeter Array (Chile), among other facilities, to detect light from the centers of distant galaxies at a frequency of about 345 GHz, equivalent to a wavelength of 0.87 mm.
In 2019, the EHT collaboration published images of the supermassive black hole at the center of the M87 galaxy, and in 2022, they released images of Sagittarius A*, which lies at the heart of the Milky Way.
Black hole images are 50% more detailed
With this new advance, the EHT team estimates that in the future they will be able to take images of black holes that are 50 percent more detailed than was possible before, bringing the region outside the boundaries of supermassive black holes into sharper focus.
In addition, they will be able to obtain images of more black holes, According to a study published Astronomical Journal.
The black hole images captured so far were taken by linking multiple radio observatories, using a technique called very long baseline interferometry (VLBI), to form a single virtual Earth-sized telescope.
Another way to increase the telescope’s resolution is to observe shorter wavelength light, which is what the EHT collaboration has now done.
Using the EHT, the first images of black holes were taken using 1.3 mm wavelength observations.
However, “the bright ring, formed by the bending of light caused by the black hole’s gravity, was still blurry, as we were at the absolute limit of how sharp the images we could take.” Alexander Raymond explained, From the Jet Propulsion Laboratory (USA) and the study site.
A new window to study black holes
The team wanted to prove they could detect 0.87 millimeters, to get sharper, more detailed images, for which they used only part of the array of telescopes that make up the EHT collaboration.
Although they haven’t been able to get images yet, they have made strong detections of light from several distant galaxies, but not enough antennas to accurately reconstruct the image from the data. This simulation of M87* shows what it looks like at 86 GHz (red), 230 GHz (green), and 345 GHz (blue). At higher frequencies, the image reveals more detail and clarity.
This technical test has opened a new window into the study of black holes. With its full suite of facilities, the EHT can see details as small as a bottle cap on the Moon from Earth.
These detections of VLBI signals at 0.87 mm are “innovative, because they open a new observational window for studying supermassive black holes,” according to Thomas Krechbaum, co-author of the study and a member of the Max Planck Institute for Radio Astronomy (Germany).
The scientist stressed that in the future “the combination of the IRAM telescopes in Spain (IRAM-30m), France (NOEMA and ALMA) and the Atacama Pathfinder experiment will allow us to obtain, simultaneously, images of smaller and weaker emissions than previously achieved.” It was possible until now at two wavelengths, 1.3 mm and 0.87″.
little (if, Astronomical Journal, Harvard-Smithsonian Center for Astrophysics
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