Supermassive Black Hole from the Early Universe Surprises Researchers

Using the unprecedented imaging and spectroscopy capabilities of the James Webb Space Telescope from NASA, ESA, and CSA, researchers have mapped the movement and composition of the gas surrounding a supermassive black hole at the center of Abell2744-QSO1, a tiny galaxy located over 13 billion light-years away. The results suggest that the black hole, with a mass 50 million times that of the Sun, is older than its host galaxy, possibly formed in the first second of the Big Bang, and must have been massive from the very beginning.

What came first, the galaxy or the black hole? Scientists long suspected it might have been the galaxy: large stars within an existing galaxy consume their fuel and collapse into black holes, which can then consume surrounding material and merge over time into even more massive entities. However, it is difficult to comprehend how black holes with millions to billions of solar masses—thousands of which have been discovered in the early universe—could have formed so quickly from such tiny seeds.

Now, researchers using the Webb telescope have found clear evidence that some supermassive black holes were enormous from the start and formed without a phase of stellar collapse or a significantly more massive host galaxy to feed on.

"This is a remarkable discovery," said Roberto Maiolino from the University of Cambridge in the United Kingdom, co-author of the studies published today in Nature and the Monthly Notices of the Royal Astronomical Society. "It is a paradigm shift, a complete rethinking of the classical scenarios of how black holes form and grow."

Little Red Dot QSO1

The team's conclusion is based on detailed observations of Abell2744-QSO1 (QSO1), a prototypical Little Red Dot that existed only 700 million years after the Big Bang.

Although QSO1 has a diameter of just 1,300 light-years and its light has been traveling for more than 13 billion years, it is easier to study than most other "Little Red Dots" because it is gravitationally distorted by the galaxy cluster Abell 2744 (Pandora Cluster). QSO1 is both magnified and imaged threefold, appearing at three different locations in the sky.

Initial investigations of QSO1 provided compelling evidence that it could be little more than a cloud of luminous hydrogen and helium gas orbiting a supermassive black hole estimated to have a mass of 40 million solar masses. However, as with other early black holes discovered by Webb, there was uncertainty about whether it was indeed that massive.

"Until now, all mass measurements of black holes in the early universe have been indirect and based on assumptions derived from our knowledge of them in the local universe. We didn't know if these assumptions actually applied to the distant universe," said co-author Francesco D’Eugenio, also from the University of Cambridge.

Mapping Gas Composition and Velocity

The team realized that if the black hole in QSO1 is as massive as it appears, they could use the Integral Field Unit (IFU) on Webb's NIRSpec (Near Infrared Spectrograph) to trace the effects of its gravity on the gas swirling around it while simultaneously mapping the distribution of various elements in the gas.

Cambridge graduate Ignas Juodžbalis and Cosimo Marconcini from the University of Florence, lead authors of one of the studies, used the IFU observations to map the movements of the hydrogen gas around the black hole. When they plotted the rotational velocity against the distance from the center, they found that the gas exhibits Keplerian motion: it orbits a central point, similar to how the planets in our solar system orbit the Sun.

"This is important because it shows us that most of the mass of QSO1 is concentrated in the black hole at the center," said Juodžbalis. "If the mass were more widely distributed, as would be the case with a large number of stars, the gas would not exhibit this perfect Keplerian rotation."

Since Keplerian motion follows the simple laws of gravity, the team was able to use the gas velocity measurements to directly calculate the mass of the black hole—a feat that had not been possible before. They found that the black hole is not only enormous—about 50 million solar masses—but also accounts for an astonishing two-thirds of the total mass of QSO1. This proportion is a thousand times greater than in nearby galaxies, where supermassive black holes make up only a tiny fraction of the total mass of the host galaxy.

The IFU composition maps confirmed these findings and showed that the gas in QSO1 is almost entirely composed of hydrogen and helium, with very small amounts of heavier elements like oxygen, which would be expected in a galaxy with many stars and stellar debris. With a metallicity of less than 0.5% of solar metallicity, QSO1 ranks among the most pristine galactic environments ever measured.

"This is a phenomenal result," said Maiolino. "It is the first direct measurement of the mass of a black hole within the first billion years after the Big Bang, and it agrees with previous measurements." The team sees this as a good sign that the assumptions used for indirect mass measurements are accurate and that the masses of other black holes in the early universe have not been overestimated.

Origins of Supermassive Black Holes

The mass of QSO1, disproportionate to its host galaxy, suggests that it could not have formed gradually from much smaller, stellar black holes that merged and grew larger. "It seems we have found a black hole that has no significant host galaxy and is older than stellar processes," said Juodžbalis. "This is very exciting because it is a hint at primordial black holes or black holes formed through direct collapse, which have been theoretically predicted but not yet confirmed."

Whether the black hole in QSO1 formed from a "heavy seed" that developed within the first second of the Big Bang or later from the collapse of a massive gas cloud, it was almost certainly large and may be in an early stage of galaxy formation around it.

The team believes that Little Red Dots like QSO1 may not have been rare in the early universe and is currently analyzing similar objects to determine whether supermassive black holes are indeed older than the galaxies in which they currently reside.

Background Information

Webb is the largest and most powerful telescope ever launched into space. As part of an international cooperation agreement, ESA provided the launch service for the telescope using the Ariane 5 rocket. In collaboration with partners, ESA was responsible for the development and qualification of the Ariane 5 adaptations for the Webb mission and for procuring the launch service through Arianespace. ESA also provided the main spectrograph NIRSpec and 50% of the mid-infrared instrument MIRI, which was designed and built by a consortium of publicly funded European institutes (the MIRI European Consortium) in collaboration with JPL and the University of Arizona.

Webb is an international partnership between NASA, ESA, and the Canadian Space Agency (CSA).

Image credit: NASA, ESA, CSA, L. Furtak (Ben-Gurion University), R. Maiolino (Cambridge), F. D’Eugenio (Cambridge), I. Juodžbalis (Cambridge), H. Übler (MPE), C. Marconcini (University of Florence). Image processing: A. Pagan