By Amit Malewar 19 Aug, 2024
Collected at: https://www.techexplorist.com/black-hole-exerts-immense-influence-life-death-home-galaxy/87393/
Cold gas is the essential raw material for star formation. For the first time, a Chinese-led study shows that the larger the black hole, the less cold gas there is in the galaxy.
Scientists examined data from 69 nearby galaxies. They found that a black hole at the center of a galaxy could warm up surrounding cold gas and prevent it from condensing and forming new stars.
This study shows that the black hole exerts immense influence over the life and death of its home galaxy.
Lad researcher Wang Tao from Nanjing University said, “Our research shows that the larger the black hole, the less cold gas there is in the galaxy.”
The work suggests a direct link between the mass of galaxies’ central black holes and their host galaxies’ atomic hydrogen gas content.
There are two types of galaxies: star-forming galaxies and passive galaxies. Passive galaxies have little or no cool gas.
What causes this galaxies’ transition from star-forming to passive?
As passive galaxies are more massive, scientists think that something has prevented galaxies from acquiring cool gas reservoirs. Since the 1970s, scientists have suggested that supermassive black holes can be so powerful when they pull in gas that they might disrupt the cool gas in their galaxies. But, until now, no one has seen this connection between the black holes and the cool gas in their galaxies.
In this study, scientists measured the stellar mass of nearby galaxies, the mass of their central black holes, and the reservoir of atomic hydrogen gas (HI) that is available.
They found that the gas reservoir decreases with a much better correlation with the mass of the central black holes.
They found that galactic mass does not define how much gas they have, but the mass of the central black hole determines the same. The more massive the black hole in a galaxy, the smaller its reservoir of atomic gas.
The accretion of matter from intergalactic space generates cool gas. This study suggests that black holes can prevent galaxies from absorbing this outside matter.
Another possibility is that black holes might push some of the gas out. However, this seems less likely because earlier studies show that even galaxies with very active black holes still have plenty of cool gas and continue to form stars, just like other galaxies.
By regulating the cool gas accretion in galaxies, black holes provide concrete evidence that central black holes affect the growth and quenching of their host galaxies.
Journal Reference:
- Wang, T., Xu, K., Wu, Y. et al. Black holes regulate cool gas accretion in massive galaxies. Nature (2024). DOI: 10.1038/s41586-024-07821-2
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