Astronomers have long thought that black holes almost exclusively feed on hot ionized gas, but this does not appear to be always the case as revealed by new observations of researchers who have spotted a supermassive black hole feeding on cold gas.
Black holes are known to feed on slow and steady diet of hot ionized gas from the halo of the galaxy, but the new observation provides the first hard evidence that support the theory that black holes also feed on clouds of cold space gas.
In the study published in the journal Nature on June 8, Michael McDonald, from MIT's Kavli Institute for Astrophysics and Space Research, and colleagues used data collected by the Atacama Large Millimeter Array (ALMA) to map the movement and location of cold molecular gas in a cluster of galaxies known as Abell 2597 located 1 billion light-years away from Earth.
They found three massive clumps of gas that individually contain about the same amount of material as a million suns. The gas was observed heading toward a black hole at the center of the cluster at a speed of 600,000 miles per hour.
The observed phenomenon suggests that black holes consume a variety of diet and not just hot ionized gas as previously believed. It also revealed the two dining styles of black holes.
"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. So the idea that there are these two dinner modes for black holes is a pretty nice result," McDonald said.
The findings likewise offer insight on how black holes consume fuel, a process also known as accretion.
"The observations show that these cold clouds also fuel black hole accretion, revealing 'shadows' cast by the molecular clouds as they move inward at about 300 kilometres per second towards the active supermassive black hole, which serves as a bright backlight," the researchers wrote in their study.
ALMA, which has already made significant space discoveries such as previously undiscovered galaxies hiding behind the Milky Way and the birth of an alien solar system, may also possibly find more evidences that the phenomenon observed in the study is common.
The researchers said that they plan to use the Chile-based network of 66 radio telescopes to look for similar rainstorms in other galaxies to know if the cosmic weather observed in the study commonly occurs.
