On 5 to 14 April 2017, the team behind the Event Horizon Telescope hopes to test the fundamental theories of black-hole physics by attempting to take the first ever image of a black hole’s event horizon (the point at which theory predicts nothing can escape).
By connecting a global array of radio telescopes together to form the equivalent of a giant Earth-sized telescope – using a technique known as Very Long Baseline Interferometry and Earth-aperture synthesis – scientists will peer into the heart of our Milky Way galaxy where a black hole that is 4 million times more massive than our Sun – Sagittarius A* – lurks.
Scientists Are Turning Earth Into a Telescope to See a Black Hole
ALMA is now one of the most important telescopes to the EHT’s upcoming two-week observing period. Should snow or rain fall in the Chilean desert during those two weeks, none of the EHT telescopes will run, said Impellizzeri. ALMA is a no/no-go facility.
Image: ALMA (ESO/NAOJ/NRAO)
There are other crucial telescopes lending their disks to the mission in April, like the South Pole Telescope. “We can always see the galactic center from the South Pole,” said Marrone. Plus, pictures imaged from North-South pairs tend to be the crispest, he said. Scientists theorize this effect comes from magnetic fields between us and the black holes.
Ultimately, all of the telescopes are important. Should one telescope fail to make observations due to bad weather, that’s less information to build the image. “If you start losing one of your dishes, you’re essentially ripping off a piece of the Earth-sized telescope,” said Doeleman.
During the upcoming EHT run, scientists will mainly monitor the telescopes and perform maintenance. The run will start by collecting 3 millimeter light waves during its first few days, and then it’ll move on to 1 or so millimeter waves for the remaining period, gathering different kinds of light for different kinds of images. After that, researchers ship all the disks—petabytes worth of data—to a central supercomputer at the Haystack Radio Observatory in Massachusetts and another in Bonn, Germany. There, the light signals’ times can be correlated and researchers can run mathematical models based on the data to actually produce the image. That requires intense pattern-matching and data machine learning algorithms—there are an infinite number of pictures that could potentially fit the data. The algorithms, written in part by MIT graduate student Katie Bouman, try to pick the image that best matches what makes the from a physical perspective.
That means we won’t see the EHT’s black hole picture until much later this year at the earliest, maybe not until next year. All of those telescopes might even need to clear their schedules for another observing run next year before we see anything meaningful. “I’m not 100 percent sure that this year they’ll get the result they expect,” said Impellizzeri, meaning a full-blown black hole picture. “Within the next couple of cycles they will. But this is the first result.”
h/t Digital mix guy