Supermassive Black Holes From the Dawn of the Universe Feasted on Halos of Gas, Study Suggests

Astronomers have discovered "gas halos" around some of the universe's earliest galaxies. It's a find scientists say could provide food for the supermassive black holes that lie at their center—and fills one of the missing pieces of the puzzle when it comes to the formation of the early universe billions of years ago.

"We are now able to demonstrate, for the first time, that primordial galaxies do have enough food in their environments to sustain both the growth of supermassive black holes and vigorous star formation," lead author Emanuele Paolo Farina, of the Max Planck Institute for Astronomy in Heidelberg, Germany, said in a statement.

"This adds a fundamental piece to the puzzle that astronomers are building to picture how cosmic structures formed more than 12 billion years ago."

The first black holes that populated the early Universe were extraordinarily large—"with masses several billion times the mass of our Sun," said Farina. It has been assumed that due to the sheer size of these black holes they would have had to have grown incredibly fast, a process that requires large amounts of gas and dust that can provide "food" for the supermassive black holes. But how exactly they achieved this remained a mystery.

Illustration Supermassive Black Hole
An illustration of a supermassive black hole. Astronomers have detected the faint glow of "gas halos" surrounding some of the earliest objects in the Universe. Thibault Renard/iStock

Writing in The Astrophysical Journal, Farina and colleagues describe how they detected reservoirs (or "gas halos") made of cool hydrogen gas around some of the earliest galaxies using the European Southern Observatory's (ESO) Very Large Telescope based in the Chilean Atacama Desert.

Specifically, the team looked at quasars—extremely bright celestial phenomena that look a bit like stars but because of their distance from Earth must be emitting much more energy.

One discovered in 2015, as an example, has the mass of 12 billion solar masses and, according to Cosmos Magazine, emits energy equivalent to 420 trillion suns. Others are not quite so big but are still among some of the brightest and most distant objects in the universe. At their centers lie supermassive black holes.

The paper involved the study of 31 quasars, which appear to astronomers today as they would have been over 12.5 billion years ago, when the Universe would have been around 870 million years old—and practically an infant in astronomical terms. Of those, 12 appeared to be surrounded by the "faint glow" of an aura made from cold, dense hydrogen. Eight of the 12 were newly discovered, say researchers.

These halos extend almost 100,000 light years outwards from the black hole, but remained closely bound, offering a potential food source for these supermassive black holes as well as a possible explanation for how they were able to grow to such colossal sizes so quickly.

"Further investigations of the detected nebulae are necessary to fully capture the physical status of the emitting material," or gas halos, the study's authors write—"however our REQUIEM survey suggest that the halos of the first quasars contain sufficient fuel to maintain the observed high–rate of gas consumption."

gas halo
This image shows one of the gas halos newly observed with the MUSE instrument on ESO's Very Large Telescope superimposed to an older image of a galaxy merger obtained with ALMA. The large-scale halo of hydrogen gas is shown in blue, while the ALMA data is shown in orange. ESO/Farina et al.; ALMA ESO/NAOJ/NRAO, Decarli et al.