The Event Horizon Telescope Collaboration’s test produced the highest-resolution observations ever obtained from Earth, laying the foundation for exciting future observations of black holes.
As we all know, the Event Horizon Telescope (EHT) provided humans with the first image of a black hole in April 2019.
The telescope itself is a network of radio telescope observatories spread across the Earth’s surface, which are synchronized and focused on specific light sources (black holes) to take clear images of the region of space-time occupied by these behemoths. Importantly, the image of a black hole is actually an image of superheated material surrounding the black hole itself, since no light can escape the black hole. The image of a black hole is actually an image of the black hole’s shadow.
The latest research from the collaboration is published today in astronomical magazine–The team describes their approach to improving the telescope’s resolution. Normally, astronomers would use larger telescopes to get higher-resolution images, but the EHT has already reached across Earth. Instead, the collaboration observed shorter wavelengths of light, producing sharper images.
“Through the EHT, we saw the first image of a black hole using 1.3 millimeter wavelength observations, but the bright ring we saw (formed by the bending of light in the black hole’s gravity) still looked blurry because we were at the absolute limit of the black hole. U.S. Alexander Raymond, a researcher at the space agency’s Jet Propulsion Laboratory and co-lead author of the study, said in a press release from the European Southern Observatory.
“At 0.87 mm, our images will be sharper and more detailed, which in turn may reveal new properties, both previously predicted and possibly some that were not predicted,” he added.
The collaboration used a subset of the arrays – ALMA and Chile’s Atacama Pathfinder Experiment (APEX) – in testing the utility of shorter wavelengths for producing sharper images. This collaboration focused the subarray on distant galaxies, achieving observations of 19 microarcseconds, equivalent to the highest-resolution images ever taken from the Earth’s surface.
Although the team achieved observations at such sharp resolution, they did not produce images because the antennas used in the study were unable to reconstruct images from the data collected.
When the collaboration refocuses attention on black holes, the improvements in resolution could be dramatic. According to a release from ESO, at certain wavelengths, the team was able to obtain images of black holes that were 50% clearer than previously released images.
In addition to the black holes it has already imaged, the improved resolution could mean the collaboration will make it easier to image more distant, smaller or dimmer black holes than the supermassive black holes imaged in 2019 and 2022.
