Solar System-sized Gas Cloud May Reveal Thousands of Black Holes at Milky Way's Core

An astronomically huge cloud of cosmic gas may reveal a vast field of black holes suspected to be at the core of the Milky Way as it passes through the center of our galaxy.

The G2 cloud, as it's known, is about the size of our entire solar system, having dimensions three times larger than the orbit of Pluto around the Sun. Frist identified in 2011, the G2 cloud is drifting toward the core of the galaxy. The power of the massive black hole at the galactic core will spin and heat the flowing gas, which will react by spitting out light observable with X-ray telescopes.

This September, the cloud will pass close by the core of the Milky Way and researchers are preparing to learn a great deal about what will happen when it does.

As Tom Fielden, science correspondent for the BBC put it when he wrote about the G2 cloud last November:

"It promises to be quite a show as all the material that doesn't get sucked into oblivion will be swept up, swirled around in a gigantic catherine wheel, heated, stretched, shredded and finally fired out again in a dazzling display of gravitational power."

Not something that happens every day in astronomy.

But the latest thoughts on the G2 cloud come from a team at Colombia University, which suggests that in addition to the fireworks caused by the big black hole, the passing of the G2 cloud will also reveal thousands of smaller black holes.

"We know that there is a very massive black hole in the center of the galaxy, many millions of times heavier than our Sun, and we also suspect that there are thousands and thousands much smaller - a few times the mass of the Sun," Columbia University's Imre Bartos told the BBC. "When I first saw this G2 cloud going toward the center, we thought that this may be the first opportunity to hopefully say something directly, to see these black holes near the center," he said.

In the abstract of the paper published in the journal Physical Review Letters, the authors wrote that the G2 cloud provides an "unprecedented opportunity" to probe the black hole and neutron star population of the galactic center.

Stefan Gillessen, one of the authors of the 2012 paper that claimed discovery of the G2 cloud, said the idea to exploit the G2 clouds passing as a way to measure for smaller black holes was solid.

"We didn't think of that when we did the original paper - I think it's something worth following up," he told BBC News.