Narrator (April Hobart, CXC): Astronomers have known for quite some time that supermassive black holes influence the growth of galaxies they live in, but they have been trying to figure out exactly how. A new study of over 200 galaxy clusters using data from NASA's Chandra X-ray Observatory is an important step in that direction. Researchers used Chandra to look at some of the largest known galaxies lying in the middle of galaxy clusters. These galaxies are embedded in enormous atmospheres of hot gas. This hot gas should cool and many stars should then form. However, observations show that something is hindering the star birth. The latest study suggests that a phenomenon referred to as cosmic precipitation may be playing a critical role. Cosmic precipitation is not rain, sleet, or snow. Rather, it is a mechanism that allows hot gas to produce showers of cool gas clouds that fall into a galaxy. Some of these clouds form stars, but others rain onto the supermassive black hole, triggering jets of energetic particles that push against the falling gas and reheat it. This prevents more stars from forming. This cycle of cooling and heating creates a feedback loop that regulates the growth of the galaxies. Future studies will test whether this precipitation-black hole feedback process also regulates star formation in smaller galaxies, including our own Milky Way galaxy.
Revised: May 19, 2022