EHT achieves record-breaking results from Earth’s surface – DW – 08/28/2024

The Event Horizon Telescope (EHT) collaboration has achieved the highest resolution observations ever made from the surface of Earth, allowing future images of black holes to be obtained with 50% more detail than ever before.

The EHT has conducted test observations with the IRAM observatory in Granada and the Atacama Large Millimeter/submillimeter Array in Chile, among other facilities, to detect light from the centers of distant galaxies at a frequency of about 345 gigahertz (GHz), equivalent to a wavelength of 0.87 millimeters.

In 2019, the EHT collaboration released images of the supermassive black hole at the center of the galaxy M87, and in 2022 they released images of Sgr A*, which is located at the center of the Milky Way.

Black hole images now 50% more detailed

The EHT estimates that this new breakthrough will allow them to image black holes in future with 50% more detail than was previously possible, allowing the region just beyond the boundary of nearby supermassive black holes to be brought into sharp focus.

In addition, they will be able to obtain images of more black holes, according to the published study. Astronomical journal.

The images of the black hole so far were made by linking multiple radio wave observatories together using a technique called very long baseline interferometry (VLBI) to form a single, virtual Earth-sized telescope.

Another way to increase the resolution of a telescope is to observe light at shorter wavelengths, and that’s what the EHT collaboration has now done.

The EHT has produced the first images of black holes using observations at a wavelength of 1.3 millimetres.

However, “the bright ring resulting from the deflection of light caused by the black hole’s gravity was still fuzzy because we were at the absolute limits of how sharp we could make images,” explained Alexander Raymond, from the Jet Propulsion Laboratory (USA) and signed the study.

A New Window for Studying Black Holes

The team wanted to demonstrate that they could make detections as small as 0.87 millimetres to get sharper, more detailed images, for which they used only a subset of the EHT collaboration’s telescopes.

Although they haven’t yet taken any images, they have reliably detected light from several distant galaxies, but not enough antennas were used to accurately reconstruct the image from the data. This simulation of M87* shows what it looks like. 86 GHz (red), 230 GHz (green), and 345 GHz (blue). At higher frequencies, the image becomes more detailed and sharper.

This technical test opened a new window on the study of black holes. With its full complement of instruments, the EHT could see features as small as a bottle cap on the Moon from Earth.

These detections of VLBI signals at a wavelength of 0.87 mm are “groundbreaking because they open a new observation window for studying supermassive black holes,” said Thomas Krichbaum, a co-author of the study and a member of the Max Planck Institute for Radio Astronomy (Germany).

The scientist emphasized that in the future, “the combination of the IRAM telescopes in Spain (IRAM-30m) and France (NOEMA), ALMA and the Atacama Pathfinder EXperiment will allow us to obtain images of even smaller and weaker radiations at the same time than what has been achieved so far.” Until now, this was possible at two wavelengths: 1.3 millimeters and 0.87 inches.

FEW (EFE, Astronomical Journal, Harvard-Smithsonian Center for Astrophysics)