Scientists at the University of Southampton have uncovered a connection between the feeding of supermassive black holes (SMBHs) and the movement of gas clouds from one galaxy to another.
An international team found that the interaction of neighboring galaxies plays a vital role in providing the large amounts of gas needed to sustain these giant, super-dense space phenomena.
The research will be published in the journal Nature Astronomy.
A black hole forms when a star collapses, compressing matter into a small area, resulting in an increase of gravity to the point where nothing, including light, can escape, thus the name “black hole.”
Supermassive black holes, which have masses millions of times greater than our sun and emit significant amounts of energy, are still not fully understood in terms of their formation and power source.
“Supermassive black holes fuel their activity by, in part, the gradual accumulation of gas from the environment around them,” explains lead researcher Dr. Sandra Raimundo.
“Supermassive black holes can make the centres of galaxies shine very brightly when they capture gas and it’s thought this process can be a major influence on the way that galaxies look today.
“How SMBHs get enough fuel to sustain their activity and growth still puzzles astronomers, but the work we have carried out provides a step towards understanding this.”
Scientists from the University of Southampton, along with researchers from the universities of Copenhagen and California, analyzed data from the 4-meter Anglo-Australian telescope in Australia to examine the orbits of gas and stars in over 3000 galaxies.
They identified those that had “misaligned” gas, which rotates in a different direction from the stars in the galaxy, indicating past interaction between galaxies.
They discovered that galaxies with misaligned gas had a greater proportion of active supermassive black holes.
The study found a strong correlation between misaligned gas and activity in supermassive black holes, indicating that gas is transferred when galaxies interact, travels long distances through space and then falls into the gravitational pull of the supermassive black hole, serving as a crucial source of fuel.
Astronomers had previously theorized that galaxy mergers could provide this source of gas, but this study provides direct evidence for this connection.
“The work that we carried out shows the presence of gas that is misaligned from stars is associated with an increase in the fraction of active supermassive black holes,” points out Dr. Raimundo.
“Since misaligned gas is a clear sign of a past interaction between two galaxies, our work shows that galaxy interactions provide fuel to power active supermassive black holes.
“This is the first time that a direct connection has been observed between the formation and presence of misaligned gas and the fuelling of active supermassive black holes.”
“What is exciting about these observations is,” adds co-author Dr. Marianne Vestergaard, “that we can now, for the very first time, identify the captured gas and trace it all the way to the centre where the black hole is devouring it.”
The researchers aim to expand their study and apply their discoveries to determine the proportion of supermassive black holes that grew through this mechanism, and how significant it was in the early Universe.
Source: 10.1038/s41550-022-01880-z
Image Credit: NASA/ESA/Hubble Heritage Team