The results of a new study were published and it seems that there is proof that big black holes stop star formation in older galaxies. It appears that the feedback consisting of radio frequencies coming from central black holes in mature galaxies can indeed prevent hot gas from cooling and making baby stars.

Tobias Marriage, from the Johns Hopkins University in Baltimore, had this to say about the study’s results:

When you look into the past history of the universe, you see these galaxies building stars. At some point, they stop forming stars and the question is: Why? Basically, these active black holes give a reason for why stars stop forming in the universe.

Scientists have managed to determine that big black holes stop star formation after studying the SZ (Sunyaev-Zel’dovich) effect signature that is normally used to study clusters of large galaxies. It appears that the effect can also be studied to find out information about smaller formations. Researcher Megan Gralla, from Johns Hopkins University in Baltimore, explains:

The SZ is usually used to study clusters of hundreds of galaxies, but the galaxies we’re looking for are much smaller and have just a companion or two. What we’re doing is asking a different question than what has been previously asked. We’re using a technique that’s been around for some time and that researchers have been very successful with, and we’re using it to answer a totally different question in a totally different subfield of astronomy.

Stars form after hot gas in drawn into a galaxy where it then cools. If the same hot gas gets sucked in a big black hole that is located inside the galaxy, then the black hole grows, as well as the stars inside the galaxy. This cycles will repeat itself forever: more gas gets sucked in the black hole, thus making it and the stars in the galaxy bigger.

But it appears that in mature galaxies, gas doesn’t cool off anymore to form new stars. It stay hot and the reason behind it is the massive black holes. Marriage revealed that the mechanism of why big black holes stop star formation is not yet fully understood and debates are still often.