Astronomers have figured out what can happen when a giant black hole does not “do its job” and does not interfere with the life of a cluster of galaxies. Using NASA’s Chandra X-ray Observatory and other telescopes, scientists have found that the behavior of a passive black hole could explain the massive star-forming stream that is occurring in a distant galaxy cluster. The results of the study are published in the Astrophysical Journal Letters.
Galactic clusters contain hundreds or thousands of galaxies permeated with hot gas. Ejections of material fueled by a supermassive black hole at the center of a cluster of galaxies usually prevent this hot gas from cooling and forming a huge number of stars. This heating allows supermassive black holes to influence or control the activity and evolution of the host cluster.
But what happens if this black hole stops being active? The SpARCS104922.6 + 564032.5 galaxy cluster (SpARCS1049 for short), located 9.9 billion light-years from Earth, provides an answer to this question.
Based on observations from NASA’s Hubble Space Telescope and the Spitzer Space Telescope, astronomers have found that stars are forming at an extraordinary rate – about 900 new solar masses per year – in the SpARCS1049 cluster. This is 300 times faster than the speed at which our galaxy, the Milky Way, forms its stars.
This reminds me of the old expression “Cat out the door – mice dance!” Here the cat, or the black hole, is quiet, and the mice, or the stars, have found something to do.
Julie Hlavasek-Larrondo of the University of Montreal in Canada led the research
This violent star formation occurs about 80,000 light-years from the center of SpARCS1049. Astronomers are wondering what is causing this stunning cycle of star birth?
The answer may come from new Chandra data revealing hot gas behavior in SpARCS1049. In most of the cluster, the gas temperature is about 65 million degrees. However, in the place of star formation, the gas is denser than average and has cooled to a temperature of only about 10 million degrees. The presence of this cooler gas suggests that other undiscovered gas reservoirs have cooled to even lower temperatures, which are allowing so many stars to form.
Without a black hole actively pumping energy into the environment, the gas could cool enough to allow stars to appear at this rate. Such a black hole could be a crucial form of star formation in the early universe, scientists emphasize.
Many astronomers thought that without the intervention of a black hole, star formation would get out of hand. Astronomers now have observational evidence that this is indeed the case.
The supermassive black hole at the center of this galaxy is running low on fuel. Losing the black hole’s fuel source prevents emissions and allows the gas to cool unobstructed, with the densest gas cooling the fastest. One explanation for this shift is that two small clusters of galaxies collided at some point in the past to create SpARCS1049, pushing the densest gas away from the central galaxy.