A collection of 13 telescopes has parted the fog to reveal the best-ever image of the supermassive black hole at the centre of our galaxy, Sagittarius A*. Matter that falls in to a black hole heats up, causing it to emit light, but Sagittarius A* is surrounded by plasma which bounces聽this light around, making it difficult to see clearly. Now astronomers are figuring out how to see through the haze.
鈥淭he galactic centre is full of matter around the black hole, which acts like frosted glass that we have to look through to see the black hole,鈥� says Eduardo Ros at the Max Planck Institute for Radio Astronomy in Germany.
Ros and his colleagues used a set of 13 telescopes spread throughout the world to take the new image (below), which has twice as high a resolution as the previous best picture. Then, they developed a computer model of the matter around the black hole to remove most of the frosted-glass effect.
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The final image revealed that Sagittarius A* looks like a point 鈥� there are no obvious signs of the powerful jets of matter and radiation that we expect around a supermassive black hole. The most likely explanations are that the the jet dies out incredibly close to the black hole or that we can鈥檛 see its shape because it鈥檚 pointed directly at Earth.
If the jet dies out close to the black hole, that would make it different from other supermassive black holes. But statistically, it is unlikely that the jet would be pointed straight at us. If it is, Ros says, we need not worry.
鈥淚f anything is there, it will be a length that is 1000 times less than the distance to us,鈥� he says. 鈥淭here is no danger at all 鈥� we should not fear the supermassive black hole.鈥�
That this image was such a success is a good sign for the Event Horizon Telescope, a huge collaboration that intends to take the first direct image of a black hole. That set of observatories will take its image using a different wavelength of light than this group, which Ros says will reduce the effects of the fog by a factor of ten. Using the method he and his team demonstrated, we should be able to peek past that fog and see the behemoth at our galaxy鈥檚 heart for the first time.
The Astrophysical Journal
