'BlackHoleCam' Will Harness Telescopes Around The World To Create First-Ever Image Of Milky Way's Black Hole
Astrophysicists believe that at the center of our galaxy is a black hole four million times more massive than the sun. But we've never seen it, something that may (sort of) change soon: a team of European astrophysicists plans to image the Milky Way's supermassive black hole with BlackHoleCam, a project that takes readings from radio telescopes from all around the world. BlackHoleCam won't image the black hole itself, but rather its "event horizon," the boundary around a black hole through which nothing--not even light--can escape.
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"While most astrophysicists believe black holes exists, nobody has actually ever seen one," said Heino Falcke, a radio astronomy professor at Radboud University in the Netherlands and one of BlackHoleCam's principal investigators. "The technology is now advanced enough that we can actually image black holes and check if they truly exist as predicted: If there is no event horizon, there are no black holes."
Flush with a €14 million grant (about $19.3 million USD) from the European Research Council, the BlackHoleCam will use a technology called Very-Long-Baseline Interferometry (VLBI) to "see" the event horizon. VLBI uses radio signal readings from multiple telescopes (in this case the new ALMA telescope in Chile will be among them). BlackHoleCam's computers then synthesize the data from the multiple telescopes, creating computer simulations based on light and matter readings from the telescopes.
What exactly are these signals that the BlackHoleCam hopes to pick up from the event horizon? At Sagittarius A*, the center of the Milky Way where the black hole is believed to be located, any gaseous matter that gets caught up there disappears. When gas gets sucked into Sagittarius A*, it lets out radio emissions. It is believed that the event horizon casts a shadow over the radio emission. According to the BlackHoleCam scientists, that shadow is incredibly small--the size of an apple on the moon, as seen from earth--but BlackHoleCam will be able to pick that up. Again, if BlackHoleCam sees images of an event horizon, that's evidence of a black hole within Sagittarius A*.
"We have made enormous progress in computational astrophysics in recent years," said Luciano Rezzolla, a principal investigator of BlackHoleCam. "We can now calculate very precisely how space and time are warped by the immense gravitational fields of a black hole, and determine how light and matter propagate around black holes."
This is the second major Milky Way initiative to take place this month. Last week, the European Space Agency launched a telescope that will map the entire Milky Way. The Gaia telescope will create a 3D map of a billion stars, which will "rewrite every star chart and every astronomy book that we have written over the centuries," according to one scientist working on the Gaia project.
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