Radio Jets from a black hole help star formation

The radio jets of a black hole are producing new cold gas in the extended halo of the galaxy, a thing that astronomers did not believe to be possible.

In the study of a galaxy in a crowded cluster named Phoenix Cluster 5,7 billion light years away was found this peculiar black hole.

The supermassive black hole in the center of the galaxy was devouring  star forming gas and projecting large jets in the intergalactic space. Astronomers refer to this type of black-hole powered system as an active galactic nucleus (AGN).

Earlier research made from the NASA Chandra X-ray observatory found that the jets from this AGN are creating bubbles that do not allow the hot gas to cool and form stars.


However the latest observations made with ALMA show long filaments of cold gas around the edges of those bubbles. They are spread at over 82,000 light years and contain over 10 billion solar masses.

“With ALMA we can see that there’s a direct link between these radio bubbles inflated by the supermassive black hole and the future fuel for galaxy growth.

“This gives us new insights into how a black hole can regulate future star birth and how a galaxy can acquire additional material to fuel an active black hole.” said Helen Russell, the lead author and astronomer at University of Cambridge.

The AGN and Galaxy Growth Connection

The observations show a previously unknown between the AGN and the star forming cold gas.

“To produce powerful jets, black holes must feed on the same material that the galaxy uses to make new stars,”

“This material powers the jets that disrupt the region and quenches star formation. This illustrates how black holes can slow the growth of their host galaxies.” said Michael McDonald, astrophysicist and co author of the paper.

If there was not a large amount of heat, the galaxies would form stars at rates far exceeding current ones. The astronomers believe that the heat that comes from jets and radiations from the feeding black hole suppress the star creation rate.

It was found that this theory does not hold in the Phoenix Cluster.It appears that there is another element that ties the black hole and its galaxy. The jets from it appear to heated its atmosphere and somehow stimulate cold gas forming.

“That’s what makes this result so surprising,” said Brian McNamara,  astronomer and co-author on the paper. “This supermassive black hole is regulating the growth of the galaxy by blowing bubbles and heating the gases around it. Remarkably, it also is cooling enough gas to feed itself.”

This peculiar result helps astronomers find out how this cosmic thermostat regulates the launching of radio jets from the supermassive black hole.

“This could also explain how the most massive black holes were able to both suppress run-away starbursts and regulate the growth of their host galaxies over the past six billion years or so of cosmic history,” noted Russell.