![]() ![]() This resolving power would also be sufficient to see an apple on the moon. This makes the EHT the only instrument on Earth that has a sufficient resolving power to directly image black holes. The shorter the wavelength of the measured radio waves, the more difficult the data processing and calibration, but the better the resolution. While there are other VLBI arrays in the world (e.g., the Very Long Baseline Array and the European VLBI Array), the EHT is special, because the other networks observe radio waves with long (centimeters) wavelengths, while the EHT observes at much shorter (millimeter) wavelengths. With the VLBI techniques, the highest resolution in astronomy can be achieved. The EHT has telescopes around the globe and is therefore a "very long baseline interferometry" (VLBI) network. What makes the Event Horizon Telescope special? Or as small shards of a big broken mirror. In an analogy, one can view the EHT array as a single big incomplete virtual radio telescope, where the individual parts are given by the handful of telescopes in our array. From the differences in arrival times, we can then reconstruct the structure of the observed source with sufficient resolution. Simply stated, we track the arrival times of radio waves emitted from the vicinity of an observed astronomical source (a black hole) at our telescopes at different locations on Earth. Here, the resolution of the instrument is no longer given by the size of a single telescope, but by the distance between pairs of telescopes. The EHT consists of several radio telescopes around the globe, which work together as an astronomical interferometer. How does the Event Horizon Telescope work? Michael Janssen is a postdoctoral researcher at the Max Planck Institute for Radio Astronomy in Bonn, Germany who conducts research with the Event Horizon Telescope (EHT). We asked Michael Janssen, a postdoctoral researcher at the Max Planck Institute for Radio Astronomy in Bonn, Germany, a few questions about the black hole imaging Event Horizon Telescope. ![]() Event Horizon Telescope FAQs answered by an expert It's no exaggeration to say, that by using this ability in 2019 the EHT was able to irrevocably shift the paradigm of astronomy and cosmology, and perhaps of science itself. The EHT Collaboration explains this is powerful enough to read a newspaper in New York from a sidewalk café in Paris! The EHT observes this phenomenon at a wavelength of 1.3 millimeters using a process called very-long-baseline interferometry (VLBI) achieving an angular resolution of 20 micro-arcseconds. This shadow caused by the gravitational bending and capturing of light when imaged can reveal a great deal about the black hole that casts it including its mass and its size. Radboud University researcher and chair of the EHT Science Council, Heino Falcke explained that if a black hole is immersed in this bright region then it should cast a shadow on this glowing gas. The tremendous gravitational influence on this material exerted by the black hole gives rise to violent conditions that cause the material to be super-heated and glow. (Image credit: EHT Collaboration)Īround some supermassive black holes is a disk of gas and dust that astronomers call an accretion disk because this material is gradually fed, or accreted, to the black hole. It shows the shadow of the monster black hole inside the distant galaxy M87. This photo is the historic first image of a supermassive black hole ever recorded. ![]()
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