An unexpected but mutually beneficial relationship has been discovered between a galaxy and a supermassive black hole located at its center. Scientists have found that the black hole can recycle its own hot gas as cold, and thereby produce fuel for star formation. Until now, astrophysicists have thought that the role of black hole jets and bubbles was to regulate star formation and prevent cooling.
The research team of scientists studied the Phoenix Cluster, a crowded collection of galaxies that lies around 5.7 billion years from Earth. The researchers had observed that Phoenix was unusually bright for a cluster located so far away from us.
Moreover, it seemed that a lot of star forming activity was taking place in the central galaxy of the cluster -- at a rate of about 500-800 stars per year. Incidentally, the Milky Way only forms 10 stars a year. Scientists found the occurrence unusual because most of the observed central galaxies are red and dead, implying that they are old and do not create stars.
The international team of researchers from the U.S.' Massachusetts Institute of Technology, the U.K.’s Cambridge University and Australia’s Melbourne University, which observed the Phoenix Cluster with Chile’s Atacama Large Millimeter Array (ALMA), found that the unusual activity could be attributed to the presence of cold gas at the edge of the superheated bubbles surrounding the central galaxy. According to The Sydney Morning Herald report, the scientists observed that the supply of cold and dense gas could eventually lead to the creation of the next generation of stars. Additionally, the amount of cold gas surrounding the galaxy is vast enough to form 10 billion Suns.
"These observations showed us that there is a black hole which is sending out jets of hot gas but at the edges the gas is cooling off and forming an ordered river as it falls back down," astrophysicist Christian Reichardt said, according to MIT News. "This is potentially an explanation for how black holes can, over billions of years, still regulate star formation."