Scientists have discovered two pairs of merging black holesand they think that the larger participant in each merger is a rare “second generation” veteran of the previous encounter.
The unusual behavior of two larger black holes, observed through ripples in space-time called gravitational waves, was described on October 28 in Letters from an Astrophysical Journal.
The results “provide compelling evidence that these black holes formed from previous black hole mergers,” said a co-author of the study. Stephen FairhurstThis was stated by a professor at Cardiff University in the UK and a representative of the LIGO scientific collaboration. statement.
Consecutive merges
The study was based on two recently discovered mergers that occurred just a month apart. Analysis of the gravitational waves from these events allowed the researchers to infer the mass, spin and distances of the black holes involved.
In the first, on Oct. 11, 2024, scientists spotted two black holes—six and 20 times the mass of the Sun, respectively— colliding in a merger known as GW241011, about 700 million light-years from Earth. The biggest black hole was one of the fastest spinning black holes ever discovered.
The second merger, GW241110, was discovered on November 10, 2024, with black holes weighing eight and 17 times the mass of the Sun. This merger occurred further away, 2.4 billion light years away. The larger black hole was also spinning opposite to its orbit, something that had never been observed before.
Scientists say each of these mergers had new properties, including that the larger black hole in each merger was almost twice the size of the smaller one, and that the larger black holes were spinning strangely compared to hundreds of other mergers observed through gravitational waves since historic first detection of LIGO (Laser Interferometer Gravitational-Wave Observatory) in 2015.
The scientists hypothesized that the larger black holes in each merger had previously come together in a process called “hierarchical merger,” which occurred in dense environments such as star clusters, where the black holes often came close to each other.
“This is one of our most exciting discoveries to date,” study co-author. Jess McIverThis was reported by an astrophysicist from the University of British Columbia. “These events provide strong evidence that there are very dense and busy regions in the Universe that are pushing some dead stars together.”
In addition to possible findings of second-generation black holes, scientists said two mergers confirmed laws of physics predicted by Albert Einstein more than a century ago, and that these events are helping scientists learn more about elementary particles.
For example, GW241011 generated a clear signal that allowed scientists to see how the large black hole was deformed as it rotated due to the black hole's rapid rotation. The resulting signature of gravitational waves coincided with Einstein's theories. and also from mathematician Roy Kerrregarding rotating black holes.
The same event also caused a “hum” in the gravitational wave signal, which occurred because the larger black hole was much larger than the smaller one. (The hum is similar to the overtones of musical instruments, the staff said.) The observation also helped confirm Einstein's predictions.
