Long ago, in a galaxy far, far away, a black hole chowed down on a chilly supper of cold gas — a clumpy rainstorm in space. Now, scientists are watching the feast unfold.
This is the first time a black hole has been seen eating such a refreshing meal: Scientists previously had only observed black holes eating slow, steady meals of hot gas shed by the spiraling galaxies they call home. Now we have evidence of a quick, spontaneous meal of cold (minus-200 degrees Fahrenheit and below), clumpy (yum) gas, formed as hot gas between the galaxies cools and condenses like a rain cloud. Observations of the binging black hole, which sits in a galaxy cluster about 1 billion light years away, were published Wednesday in Nature.
“The simple model of black hole accretion consists of a black hole surrounded by a sphere of hot gas, and that gas accretes smoothly onto the black hole, and everything’s simple, mathematically,” co-author Michael McDonald, assistant professor of physics in MIT’s Kavli Institute for Astrophysics and Space Research, said in a statement. “But this is the most compelling evidence that this process is not smooth, simple, and clean, but actually quite chaotic and clumpy.”
Using the Atacama Large Millimeter/submillimeter Array (ALMA) telescope in Chile, the researchers mapped a trio of gas clouds in the Abell 2597 cluster — a grouping of 50 galaxies, one of which hosts the black hole in question. The clouds, each of which contains the mass of around a million suns, are speeding toward the cluster's delicious black hole center at speeds of almost 800,000 mph in a process called accretion. 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.
“Although it has been a major theoretical prediction in recent years, this is one of the first unambiguous pieces of observational evidence for a chaotic, cold ‘rain’ feeding a supermassive black hole,” lead study author Grant Tremblay of Yale University said in a statement. “It’s exciting to think we might actually be observing this galaxy-spanning ‘rainstorm’ feeding a black hole whose mass is about 300 million times that of our Sun.”
Kind of makes you feel better about that midnight fridge raid, right?
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.”