During the Cosmic Dawn, supermassive black holes fed on gas halos, cold gas reservoirs that settled around some of the early galaxies of the universe. This is why these supermassive black holes, true cosmic "monsters", grew so rapidly in this period of universe history.
The observation was made with the help of ESO's Very Large Telescope, the Southern European Observatory, which helps put together another piece in the puzzle that helps understand how cosmic structures formed more than 12 billion years ago. behind. The research was published today in The Astrophysical Journal, reporting on the work of a team involving Portuguese researcher Tiago Costa, who is pursuing a postdoctoral research at the Max Planck Institute for Astrophysics in Garching bei München, Germany.
“We can demonstrate for the first time that early galaxies have enough“ food ”in their vicinity to make supermassive black holes in their centers grow while maintaining intense star formation,” explains Emanuele Paolo Farina of the Institute. Max Planck of Astronomy in Heidelberg, Germany, who led the research work.
How supermassive black holes grew so early in the history of the universe has been a mystery, and it is now possible to put together one more piece to understand the phenomenon. The researcher explains that it was estimated that the first black holes, which must have formed from the collapse of the first stars, grew very fast, but so far astronomers had not discovered “black hole food” – ie gas and dust – in sufficiently large quantities to explain this rapid growth.
Previous observations from the Atacama Large Millimeter / submillimeter Array (ALMA) revealed an enormous amount of dust and gas in these early galaxies, but it seemed to essentially trigger very intense star formation, suggesting that very little material could be left to feed a black hole.
Quasars Billions of Years Old
It was to unravel this mystery that Farina and the team of researchers from various countries, including the Portuguese Tiago Costa, used the MUSE (Multi Unit Spectroscopic Explorer) instrument, mounted on ESO's Very Large Telescope (VLT), located in the Chilean desert of the Atacama, to study quasars, extremely bright objects located in the center of massive galaxies and fed by supermassive black holes.
Through this study, 31 quasars were observed, seen as they were over 12.5 billion years ago, at a time when the universe was still very young, only 870 million years old. It is one of the largest studied samples of such primordial quasars in the history of the universe, says the statement from ESO.
During the investigation astronomers discovered that 12 of these quasars are surrounded by huge gas reservoirs. They are dense, cold gaseous hydrogen halos that extend up to 100,000 light years away from the central black holes with billions of solar masses. The team also found that these gas halos are tightly linked to the galaxies, thus providing them with a perfect "food" source for maintaining both black hole growth and intense star formation.
The sensitivity of the VLT-mounted MUSE was considered “decisive” in the quasar study. “With just a few hours of observation per target, we were able to investigate the surroundings of the largest and most starving black holes in the early universe,” says Farina.
Although quasars are very bright, the surrounding gas reservoirs are much harder to observe. Even so, it was possible to detect the faint glow of hydrogen gas in the halos, allowing astronomers to finally discover these “food” deposits that fed the supermassive black holes in the early universe.
It is expected that in the near future ESO's Extremely Large Telescope (ELT) could help scientists reveal even more details about the galaxies and supermassive black holes that existed in the first two billion years after the Big Bang. .