Scott Noble / RIT
A simulation shows superheated plasma swirling around the black hole at the center of our galaxy.
Astronomers are setting up a virtual telescope as wide as our planet to capture the first picture outlining our galaxy's monstrous black hole.
"Everybody's super-excited," one of the leaders of the effort, astrophysicist Dimitrios Psaltis of the University of Arizona's Steward Observatory, told me today. "A couple of years ago, this was science fiction. Now it's becoming a reality."
Psaltis and his colleagues are calling together researchers from around the world for a conference in Tucson starting Wednesday, with the aim of combining up to 50 radio telescopes from Taiwan to the Netherlands to the South Pole into one big observing instrument they call the "Event Horizon Telescope."
The observations have to be done by radio telescopes sensitive to millimeter-scale wavelengths, because that's the ideal range for seeing through "the dust and the mess" at the center of our Milky Way galaxy, Psaltis said.
By combining millimeter-wave radio readings from widely separated antennas, astronomers can produce an unparalleled picture of the region around our Milky Way's central black hole. "We expect to see the swirling of matter going into the black hole in real time," Psaltis said. "What we're really hoping to see is how the black hole is fed."
Black hole in the neighborhood
A black hole is an object so massive that nothing, not even light, can escape its gravitational grip within a boundary known as the event horizon. Black holes can be created by the catastrophic collapse of massive stars, and a much larger breed can take root at the center of galaxy during its formation. The black hole at the center of the Milky Way is relatively frugal in its dining habits, and that's probably a good thing for us: Scientists have suggested that the violent galactic environment associated with more ravenous supermassive black holes wouldn't be conducive to life as we know it.
Even though our galaxy's black hole is thought to have the mass of 4 million suns, and even though astronomers have determined its location by charting its gravitational effect, astronomers have never seen it directly. The black hole itself would be nothing more than a black spot, surrounded by a blazing swirl of inward-falling matter. Its extent is said to be no more than the width of Mercury's orbit around the sun, and astronomers would be watching it from a distance of 26,000 light-years. Actually seeing the "shadow" or silhouette of the black hole's event horizon would be as challenging as spotting a grapefruit on the moon, according to a University of Arizona news release.
Despite those challenges, the astronomers behind the Event Horizon Telescope believe the observation can at last be made, in part because of promising results from a pilot study conducted using the Steward Observatory's Submillimeter Telescope in Arizona, the James Clerk Maxwell Telescope on Mauna Kea in Hawaii and the Combined Array for Research in Millimeter-wave Astronomy in California.
"Those three telescopes told us that we can actually observe all the way to the black hole," Psaltis told me.
Now more telescopes will be brought into the network, including the 50-antenna Atacama Large Millimeter Array in Chile, also known as ALMA. Sheperd Doeleman of MIT's Haystack Observatory, who is the principal investigator for the Event Horizon Telescope, says ALMA's participation will be a "real game-changer."
"We will be able to actually see what happens very close to the horizon of a black hole, which is the strongest gravitational field you can find in the universe," he said in the news release. "No one has ever tested Einstein's general theory of relativity at such strong fields."
Observing the bright outline that defines the black hole's shadow could serve as an unprecedented test of general relativity, Psaltis said. If the outline is precisely circular, that would be in line with what Einstein's theory predicts. But if the outline turns out to be elliptical, the theory "must be flawed" in some way, he said.
Psaltis emphasized that the black hole picture would not take shape all at once. Instead, the details would emerge gradually as more and more readings are sent to the project's central data processing center at MITs' Haystack Observatory.
"In perhaps three years, we'll be able to have the first complete picture of the black hole," he said.
More about black holes:
- How a black hole throws fastballs
- Zoom in on the black hole next door
- Our monster black hole will get a colossal feast
- Cygnus X-1 provides answers to black hole questions
- KVOA: Scientists meet in Tucson to get set for black hole picture
Alan Boyle is msnbc.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.