Black holes are not just surrounded by hot gas, as originally thought. Scientists have recently observed one with pockets of cold gas that condenses out of hot gas and “rains” into the black hole.
Astrophysicists have observed activity in the Abell 2597 Brightest Cluster Galaxy, where the center is a supermassive black hole. Abell 2597 is a cluster of 50 galaxies located 1.23 billion light-years from Earth.
The scientists from the Atacama Large Millimeter/Submillimeter Array (ALMA) in Northern Chile found that Abell 2597 contained not only the expected warm, ionized gas (the outer region is heated by intense radiation from the surroundings), but cooler colecular gas. Clumpy rain of cold molecular gas clouds moved toward the core, clouds that are dozens of light-years across.
They called it “rain,” though it is really cold gas bubbles falling out of a hot cloud racing toward a black hole at seven thousand miles per hour. Dr. Grant Tremblay, astrophysicist from Yale University and lead author of the study looked at the center of Abell 2597 and noticed the shadow that the gas clusters were casting and observed that gas bubbles were falling into the black hole.
It’s simply a beautiful, clean demonstration of cold gas moving inward toward the heart of the galaxy. (Over time), if the clouds really are that close to the black hole, we should see them physically move on human timescales – that is, six months to a few years. We might actually see a movie of cold black hole accretion! That would be really, really cool. If these “cold rainstorms” are both long-lived and common in massive galaxies it might mean that our understanding of black hole growth needs to be reconsidered.
Though, the study cannot generalize that this “weather” occurs in other galaxies, it opens up the possibility and gives the scientists a basis for further study.