Massive black holes can block the formation of new stars in older galaxies by blasting out a large volume of radio-frequency-emitting particles, according to a new study by Johns Hopkins University.

The findings, published in the journal Monthly Notices of the Royal Astronomical Society, provides evidence that jets of “radio-frequency feedback” that are spewed from black holes at near-light speed can prevent the hot gas that would normally lead to the formation of a star from cooling and collapsing, according to a statement from Johns Hopkins.

Tobias Marriage, assistant professor of physics and astronomy at Johns Hopkins and co-lead author of the study, said the team noticed that at a certain point, galaxies simply stop forming stars, and the research has revealed that the black holes are a significant reason.

To make these findings, the team examined the Sunyaev-Zel’dovich effect signature, which is usually used to study large galaxy clusters and can also help with smaller galaxies. Also referred to as the SZ effect, it happens when high-energy electrons in hot gas combined with the much fainter light in what is called the cosmic microwave background — light left over from the beginning of the universe.

The SZ effect is usually to study hundreds of galaxies, but in this case the team was able to detect the effect in active galactic nuclei.

Normally, hot gas drawn into a galaxy cools and condenses, collapsing into baby stars, while some of the gas gets sucked into the galaxy’s black hole, causing it to grow. But the team found that in almost all mature galaxies, the gas stops cooling, which prevents it from collapsing into a star. The study found a high correlation between a lack of new stars in a galaxy — despite the presence of hot gas — and a high amount of radio-frequency feedback.

There are still unsolved mysteries, however. Scientists still have not determined why black holes in mature galaxies begin to emit radio-frequency feedback.