Ground-based 'Earth-sized' telescope achieves unprecedented ground resolution in space observations
The Event Horizon Telescope (EHT) Collaboration has made a significant breakthrough in black hole imaging capability, achieving observations at a submillimeter wavelength of 0.87 mm - a first for ground-based astronomy. This advancement, which was conducted using coordinated subarrays of the EHT, has resulted in images with a resolution 50% higher than those previously captured, offering a glimpse into the finer structure of black holes.
By operating the EHT at this specific submillimeter wavelength, the team was able to improve image resolution by approximately 50% compared to previous observations at longer wavelengths. This shorter wavelength improves spatial resolution due to the inverse relationship between wavelength and resolving power in interferometry.
The choice of 0.87 mm was strategic, as it lies in the submillimeter band, where Earth's atmosphere is more challenging for observations but offers higher angular resolution. Operating at this wavelength required precise calibration and coordination of multiple telescopes equipped with sensitive detectors capable of operating efficiently at this band.
The new observations could enable the study of black holes more distant and much smaller than those imaged so far. The team used two smaller subarrays for the 0.87 mm experiment, including the Atacama Large Millimeter/submillimeter Array (ALMA) and the Atacama Pathfinder EXperiment (APEX) in Chile, the IRAM 30-meter telescope in Spain, the NOrthern Extended Millimeter Array (NOEMA) in France, the Greenland Telescope, and the Submillimeter Array in Hawaiʻi.
In the future, the combination of the IRAM telescopes, NOEMA, ALMA, and APEX will enable imaging of even smaller and fainter emission than has been possible thus far at two wavelengths, 1.3 mm and 0.87 mm, simultaneously. The EHT Collaboration also predicts that the future combination of telescopes will allow for simultaneous imaging at two wavelengths, 1.3 mm and 0.87 mm.
Thomas Krichbaum, co-author of the study, stated that these VLBI signal detections at 0.87 mm open a new observing window for the study of supermassive black holes. The team using the EHT detected light from several distant galaxies, and they anticipate that the new observations at 0.87 mm will potentially reveal new properties of black holes.
The EHT is an array of telescopes stretching across the globe, and normally in astronomy, better observations result from bigger telescopes. However, since the EHT is already effectively the size of Earth, the team opted to observe in shorter wavelengths to achieve sharper images. At 0.87 mm, the images will be sharper and more detailed, potentially revealing new properties of black holes.
The EHT is most famous for its images of the supermassive black hole in galaxy M87 and the image of the supermassive black hole at the centre of the Milky Way. With the new observations at 0.87 mm, the team predicts they could see details as small as 13 microarcseconds, equivalent to seeing a bottle cap on the Moon from Earth.
The team achieved observations with a resolution of 19 microarcseconds, the highest-ever resolution achieved solely from the surface of Earth. For more information about the EHT project, visit eventhorizontelescope.org.
- The Event Horizon Telescope (EHT) Collaboration, using a strategic choice of 0.87 mm wavelength, operated in the submillimeter band for the observations, taking advantage of the higher angular resolution it offers despite the Earth's atmosphere being more challenging.
- The EHT team, after operating at 0.87 mm, was able to improve the image resolution by approximately 50% compared to previous observations at longer wavelengths, using interferometry's inverse relationship between wavelength and resolving power.
- The Advancements made by the EHT Collaboration in black hole imaging at the submillimeter wavelength of 0.87 mm could potentially enable the study of black holes that are more distant and much smaller than those imaged so far, due to increased resolution and detail in the images.
- The EHT Collaboration's work with the telescopes arrayed across the globe, operating at 0.87 mm, resulted in images with a resolution of 19 microarcseconds, the highest-ever resolution achieved solely from the surface of Earth, offering unprecedented glimpses into the finer structure of black holes, contributing significantly to the field of astronomy and space-and-astronomy technology.
