The Event Horizon Telescope attempted to view its black hole in the radio, and was successful, where its view of Sagittarius A* was not. Despite its mass of 6.6 billion Suns, it is over 2000 times farther away than Sagittarius A*. At the top is optical from Hubble, at the lower-left is radio from NRAO, and at the lower-right is X-ray from Chandra. The second-largest black hole as seen from Earth, the one at the center of the galaxy M87, is shown. And you need a galaxy that's radio-transparent, meaning that you can actually see all the way to the black hole without being confounded by foreground radio signals. You need a galaxy that's radio-loud, meaning that it emits a radio background that's sufficiently strong to actually stand out against the silhouette of the event horizon.You have to have the right resolution, meaning that your telescope (or telescope array) needs to see the object you're viewing as more than a single pixel.This requires three things to all line up in your favor: When you view a black hole, what you're attempting to see is the background radio light surrounding the enormous mass at a galaxy's center, where the event horizon of the black hole itself sits in the foreground of part of the light, revealing a silhouette. But for Sagittarius A*, we didn't quite get as lucky. X-ray: NASA/UMass/D.Wang et al., IR: NASA/STScIįor M87, we saw everything we could've hoped for. It has a mass of about four million Suns, and is found surrounded by hot, X-ray emitting gas. An X-ray / Infrared composite image of the black hole at the center of our galaxy: Sagittarius A*.
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