Black Hole Jets May Be Shaping the Fate of Entire Galaxies, Study Finds

Astronomers have found evidence that jets released by supermassive black holes can transfer energy to gas surrounding their host galaxies, potentially affecting star formation, according to a study involving researchers from India and the US.

The study, published in The Astrophysical Journal Letters, examined the circumgalactic medium (CGM), a diffuse reservoir of gas surrounding galaxies and extending far beyond their visible stellar disks.

Researchers from the Raman Research Institute (RRI), an autonomous institute of the Department of Science and Technology, and Arizona State University investigated whether black hole jets could influence gas within the CGM.

Black holes at galaxy centres can launch jets of hot plasma, consisting of charged particles. The researchers examined whether these jets could disturb gas outside the stellar region.

The team searched for the glow produced by ionised gas in the CGM. When measurements were averaged in all directions around galaxies, they did not detect a clear signal. However, a signal appeared when observations were examined along the direction of the black hole jets.

The finding showed that the jets were illuminating gas along their paths rather than affecting material uniformly.

The strongest signal was detected in two regions. One was near the edge of the stellar disk, where the jet first encountered the CGM. The other was near the outer boundary of the CGM, where the slowed jet interacts with surrounding gas.

The researchers said energy deposited by the jets can heat and disturb the gas. Since cooler gas can clump together to form stars, such heating may prevent some gas from cooling and collapsing, thereby suppressing star formation.

Namrata Roy, assistant professor in the Astronomy and Astrophysics division at RRI and lead author, said the directional signal showed that the jet was illuminating gas in its path.

Sanchayeeta Borthakur, associate professor at Arizona State University and a co-author, said the findings indicate that black holes can influence galaxies beyond their central regions.

The study links black hole jets with surrounding gas and galaxy evolution.