Massive Black Holes: Potential Remnants from the Early Universe Explained

An exceptionally massive black hole from the early universe may represent a type of exotic starless black hole first theorized by Stephen Hawking.

In August, Boyuan Liu and his team from the University of Cambridge used the James Webb Space Telescope (JWST) to uncover a peculiar galaxy named Abell 2744-QSO1. This ancient galaxy, dating back 13 billion years, harbored a black hole around 50 million times the mass of our Sun but hosted extremely few stars.

“This contradicts traditional theories which dictate that stars must form prior to or simultaneously with black holes,” Liu explained. Typically, black holes are believed to evolve when massive stars exhaust their fuel and undergo gravitational collapse.

Liu and his team conducted initial simulations suggesting that QSO1 might have originated as a primordial black hole—an exotic concept introduced by Stephen Hawking and Bernard Carr in 1974. Unlike conventional black holes, primordial black holes are thought to form from density fluctuations shortly after the Big Bang.

While most primordial black holes likely evaporated by the time of the JWST’s observations, some might have persisted, evolving into larger black holes like QSO1.

Although Liu and his team’s calculations align broadly with their observations, they remain relatively simple and do not factor in the intricate interactions among primordial black holes, gas clouds, and stars.

Now, the authors have employed advanced simulations to investigate how primordial black holes grew in the universe’s infancy. They analyzed how gas dynamics influenced the formation of early primordial black holes and how interactions with newly formed and dying stars affected them.

Their predictions about the black hole’s ultimate mass and the heavy elements present in it are congruent with the findings from QSO1.

“It’s not conclusive, but it represents a compelling possibility,” Liu stated. “These observations suggest that established black hole formation theories may not fully explain the phenomenon, making the notion of a significant primordial black hole in the early universe increasingly plausible.”

Simulations indicate that primordial black holes could be a feasible origin for QSO1, according to Roberto Maiorino, a team member involved in the discovery of black holes. “The alignment of their predicted properties with those of QSO1, in terms of black hole mass, stellar mass, and chemical composition, is both intriguing and promising.”

However, standard models of primordial black holes typically predict that their maximum mass should be around a million solar masses, while Maiorino pointed out that QSO1 is 50 times larger. “Nevertheless, it’s plausible that these primordial black holes are densely concentrated, allowing them to merge and grow rapidly,” he noted.

A further challenge arises from the requirement that for a primordial black hole to initially collapse, a burst of high-energy radiation, like that from a nearby supernova, is essential; however, no potential sources have been identified near QSO1, according to Maiorino.

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