Black hole activities suppress the birth of new stars around it: Study

A new study led by astronomers at the Indian Institute of Astrophysics (IIA) has found that black hole activities suppress the birth of new stars around it.

Supermassive black holes at the centres of galaxies are known to drive outflows of gas, and astronomers have long studied how feedback processes from these outflows can in turn determine the evolution of these galaxies.

However, a key puzzle has been to understand the relative influence of this gas outflow versus radiation from the central regions on the behaviour and evolution of the host galaxy.

The astronomers have uncovered key insights into these powerful forces shaping the universe. The Department of Science and Technology said that the study reveals that both intense radiation from around the black holes as well as the high-speed jets they emit can work together to eject gas from the centres of galaxies, potentially shutting down star formation in their central regions and regulating galactic growth.

Using cutting-edge archival data from international astronomical facilities like the Sloan Digital Sky Survey (SDSS) Telescope at optical wavelengths and the Very Large Array (VLA) at radio wavelengths, both located in the United States, the researchers studied over 500 relatively nearby galaxies hosting active galactic nuclei (AGN).

“AGN are energetic galaxy centres that emit copious radiation and gas, powered by matter falling onto their supermassive black holes, many millions of times more massive than our Sun,” the department said.

“We found that outflows of warm ionized gas are widespread in AGN, and while radiation from the black hole is the main driver, galaxies with radio jets show significantly faster and more energetic outflows,” said Payel Nandi, a Ph.D. student at IIA and the lead author of the study.

Their investigation further showed that such outflows, which are high-speed streams of gas pushed out from galactic centres, are more than twice as likely in galaxies detected in radio wavelengths (56%) compared to those without radio emission (25%).

“These powerful winds can travel at speeds of up to 2,000 km per second, fast enough to escape the gravitational pull of the galaxy itself,” the department said.

Dhruba J. Saikia from the Inter-University Centre for Astronomy and Astrophysics and co-author said that these findings are an important step in understanding the complex inter-relationships between supermassive black holes, radio jets, star formation, and evolution of their host galaxies.