Two massive black holes found in collision-created “fossil galaxies” were located about 750 million light years away. The binary system of black holes weighs around 28 billion solar masses, and due to their masses, they “refuse” to collide and unite.
The most massive black hole duo
The duo in elliptical “fossil” galaxy B2 0402+379 represents the most massive black hole binary ever found. According to a report from the Astrophysical Journal, published on January 5, 2024, only 24 lightyears separate the duo, and they have been “dancing around” each other for over 3 billion years.
The team that found the binary in data collected by the Gemini North telescope in Hawaii believes that massive black holes are being stopped from merging due to their tremendous mass.
Roger Romani, a physics professor at Stanford University, said in a statement, “Normally, it seems that galaxies with lighter black hole pairs have enough stars and mass to drive the two together quickly.” However, the professor pointed out, “Since this pair is so heavy, it required lots of stars and gas to get the job done. But the binary has scoured the central galaxy of such matter, leaving it stalled.”
Stubborn monsters
Scientists observing the two massive black holes speculated that they are not compatible yet, and due to their masses, nothing has slowed them down. Lead author Tirth Surti, a physics student at Stanford, said the team is looking forward to a follow-up investigation of B2 0402+379’s core to determine how much gas is present.
Scientists speculate that the supermassive black holes at the core move together when galaxies collide. When these supermassive black holes get close enough, their gravitational forces should cause them to collide and merge. However, two supermassive black holes have not yet merged, leaving scientists in awe.
Surti added that a follow-up investigation should help us understand whether the supermassive black holes can merge or “if they will stay stranded as a binary.”
“Fossil cluster”
B2 0402+379 is a so-called “fossil cluster,” meaning that it results from merging an entire set of galaxies. After such mergers, black holes do not collide head-on. Instead, they tend to pass by each other and form an orbit around a common center of gravity. During this process, energy is transferred from the black holes to the nearby stars, causing the black holes to lose energy and move closer. Eventually, in the case of stellar mass black holes, they merge. However, this phenomenon does not occur with supermassive binary black holes.
However, if these two massive black holes merge, the resulting gravitational wave is potentially hundreds of millions of times more potent than a stellar mass merger.
