It’s hard to believe how much the idea of black holes can stretch our understanding of the universe. Surprisingly, even the great Einstein had his doubts about their existence despite his own groundbreaking theory of general relativity predicting them!
Recently, astrophysicists stumbled upon something that pushes the limits of what’s possible: a phenomenal clash between two colossal black holes. This event has sparked questions about whether such a merger could even occur.
According to a new study that hasn’t yet been peer-reviewed, these merging black holes resulted in a cosmic entity designated GW231123, which turns out to have a jaw-dropping mass around 225 times that of our Sun. This makes it the largest black hole merger ever observed, eclipsing the previous record of a 140 solar masses merger.
Mark Hannam from LIGO shared in a statement, “These giant black holes defy conventional stellar evolution models. This discovery challenges everything we think we know about how black holes come to be.”
Black holes produce intense ripples in the fabric of space and time called gravitational waves, a phenomenon first theorized by Einstein in 1916. Fast-forward nearly a century, and the LIGO project—comprising two observatories across the US—made history by detecting these cosmic disruptions.
The monumental merger was detected back in November 2023, with the GW231123 signal lasting only a brief moment. Yet, this fleeting detection was enough to analyze the original black holes’ masses, revealing one was about 137 times that of the Sun, and the other came in at roughly 103 solar masses. Before the grand collision, the two black holes were like dance partners, circling each other frantically before merging into one.
This celestial event is tricky because the black holes might fall into what’s termed an “upper mass gap” in stellar evolution. Typically, stars of this immense size would explode in a cataclysmic event known as a pair-instability supernova, which would obliterate them without leaving a trace, not even a black hole.
While some experts feel the “mass gap” is better explained by our observational limitations rather than an unexplained phenomenon, it remains a contentious discussion. Cole Miller from the University of Maryland, not involved in this research, expressed the uncertainty, stating, “It’s a debate that some people are willing to champion, but it’s far from a definitive conclusion.”
Another intriguing idea is that these black holes may not have originated from a single star at all.
“One possibility is that these two black holes in this merger came together after previously merging with smaller black holes,” noted Hannam.
Their spins are equally fascinating, with the larger rotating at an astonishing 90% of the maximum speed, while the smaller one achieves 80%, both oscillating at rates that approach fractions of light speed. This translates to around 400,000 times faster than Earth’s rotation, said scientists.
According to Charlie Hoy from LIGO, “Both black holes spin incredibly fast—almost at the limit defined by Einstein’s theory. This makes it nearly impossible to model and interpret the signal effectively. It’s a vital case to help refine our theoretical approaches moving forward.”
The results of this groundbreaking discovery will be shared at the GR-Amaldi conference in Glasgow this week. According to LIGO scientist Gregorio Carullo from the University of Birmingham, “It will take years for the scientific community to completely unveil the complexities of this signal and what it signifies, meaning we’ve only scratched the surface of this incredible mystery.”
