Astronomers Discover Bizarre ‘Infinity’ Galaxy

Yale astronomer Pieter van Dokkum and his team have identified a remarkable object in deep space, which they’ve named the “Infinity” galaxy. This structure is actually made up of two galaxies that recently collided, forming a shape reminiscent of the infinity symbol. At the heart of this formation, the researchers report the presence of a supermassive black hole, nestled within a dense cloud of gas. Their findings were published in the Astrophysical Journal Letters.

According to the team, the discovery stands out for several compelling reasons. It may point to a new mechanism for how black holes form, offer insight into how massive black holes could have existed so early in the universe’s history, and possibly represent the first direct observation of a supermassive black hole shortly after its birth.

“This is as close to a smoking gun as we’re likely ever going to get,” said van Dokkum, the Sol Goldman Family Professor of Astronomy and professor of physics in Yale’s Faculty of Arts and Sciences and lead author of the new study.

Everything about this galaxy, he said, is unusual.

“Not only does it look very strange, but it also has this supermassive black hole that’s accreting a lot of material,” he said. “The biggest surprise of all was that the black hole was not located inside either of the two nuclei of the merging galaxies, but in the middle. We asked ourselves: how can we make sense of this?”

Van Dokkum and astronomer Gabriel Brammer of the University of Copenhagen made the discovery while studying images from the COSMOS-Web survey, which is part of the data archives of NASA’s James Webb Space Telescope.

Van Dokkum also led follow-up observations of the Webb data. In addition, the researchers used W.M. Keck Observatory data for the study, and archival data from the National Radio Astronomy Observatory’s Very Large Array and the Chandra X-ray Observatory.

Finding a black hole that is not located in the nucleus of a massive galaxy is, in itself, unusual, the researchers said. To then discover that the black hole had only just formed was unprecedented.

“In other words, we think we’re witnessing the birth of a supermassive black hole — something that has never been seen before,” van Dokkum said.

The finding also has implications for the ongoing debate about the formation of black holes in the early universe.

One theory — the “light seeds” theory — is that small black holes formed when stars’ cores collapsed and exploded. Eventually, those “light seed” black holes merged into supermassive black holes. This theory, however, would require an extraordinarily long time to reach fruition. And the Webb telescope already has identified supermassive black holes that appeared in the universe too early to be explained by the “light seeds” theory.

That leaves the “heavy seeds” theory, which has been championed by Yale astrophysicist Priyamvada Natarajan and others. This theory suggests that much larger black holes can form from the collapse of large clouds of gas. The sticking point for the “heavy seeds” theory has been that collapsing gas clouds usually form stars.

The Infinity galaxy, however, may show how extreme conditions — including those in the early universe suggested by the “heavy seeds” theory — could lead to the creation of a black hole, van Dokkum said.

“In this case, two disk galaxies collided, forming the ring structures of stars that we see,” he said. “During the collision, the gas within these two galaxies shocks and compresses. This compression might just be enough to have formed a dense knot, that then collapsed into a black hole.

“While such collisions are rare events, similarly extreme gas densities are thought to have been quite common at early cosmic epochs, when galaxies began forming,” he added.

Van Dokkum and his colleagues stressed that additional research is needed to confirm the findings and what they portend for black hole formation.

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