A conference being held this week in Arizona will lay the groundwork for an attempt to visualize the supermassive black hole that resides at the heart of our galaxy.
Since a black hole absorbs light itself, the Event Horizon Telescope (EHT) team is looking for the ring of matter that forms around the perimeter of the structure. If Einstein’s equations behind the General Theory of Relativity are correct, the matter around the edge of the event horizon will form a circle as it spins around the rim.
“Black holes are like babies, they are very messy eaters,” Sheperd Doeleman, principal investigator of the EHT, told The Register. “A lot of what a black hole tries to eat ends up sprayed across the galaxy.”
The EHT program will plan how to coordinate 50 radio telescopes across our planet to focus on the black hole center of our galaxy. This galactic maw has around four million times the mass of our sun and is 26,000 light years away – about 245,979,000,000,000,000 kilometers, give or take a few trillion. Trying to image this from earth is the equivalent looking for a grapefruit on the surface of the moon – catching an image of the black hole's surroundings will take a telescope over 2,000 times as powerful as Hubble, according to Doeleman.
There are many black holes in our galaxy, but almost all are relatively small and thus hard to spot. It is thought that they originated as stars that went supernova, but the hole at the galactic center is a different kettle of fish, thought to have grown concurrently with the galaxy, and is big enough to be visible.
“We’re hunting big game, we need a large target to see,” Doeleman explained. “The galactic center is the Goldilocks black hole, just at the right distance and mass to resolve the event horizon.”
The team has already conducted a preliminary scan, using three networked radio telescopes, which have determined that there is an object in the target zone. Now many more telescopes are needed to capture the first images of the center of the Milky Way – a project that could be completed in the next three or four years, now that the team has proven that it’s technically possible and that there is an object to study. ®