For the first time, astronomers have detected clouds of cold, clumpy gas streaming toward a black hole at the center of a massive galaxy cluster, 1 billion light years from Earth.
Using the Atacama Large Millimeter/submillimeter Array (ALMA) telescope in Chile, the researchers mapped a trio of gas clouds in the Abell 2597 cluster.
The clouds, each of which contains the mass of around a million suns, are speeding toward the cluster’s black hole center at an unbelievable speed of up to 800,000 miles per hour. At just 150 light years away from the black hole’s edge, the clouds are pretty much doomed to become dinner. They’ll likely merge into its accretion disk, mingling with the slow trickle of hot gas that provides its regular dinners, before sliding into oblivion.
“This diffuse, hot gas is available to the black hole at a low level all the time, and you can have a steady trickle of it going in,” Michael McDonald, assistant professor of physics in MIT’s Kavli Institute for Astrophysics and Space Research, told MIT News.
“Every now and then, you can have a rainstorm with all these droplets of cold gas, and for a short amount of time, the black hole’s eating very quickly,” McDonald said. “So the idea that there are these two dinner modes for black holes is a pretty nice result.”
Given the new observations, McDonald says black holes probably have two ways of feeding. Grazing on a steady diet of diffuse hot gas and gobbling up clumps of cold gas as it comes nearby.
The researchers hope to look for more black holes with unusual appetites, but they may never find one so voracious again.
“We got very lucky,” McDonald said. “We could probably look at 100 galaxies like this and not see what we saw just by chance. Seeing three shadows at once is like discovering not just one exoplanet, but three in the first try. Nature was very kind in this case.”