Astronomers measure the most massive pair of black holes ever found

While the close separation between the black holes predicts a powerful merger, studies have shown that the pair has been stuck at this distance for more than three billion years, raising questions; What is support?

Using archival data from the Gemini North telescope, a team of astronomers has measured the pair supermassive black hole The heaviest ever found: 28 billion times the mass of the Sun.

Almost all massive galaxies host a supermassive black hole At its center. When two galaxies merge, their black holes They may form a binary pair, meaning they orbit each other closely.

It has been speculated that these binaries are intended to eventually merge, but this has never been observed. The question of whether such an event is possible has been a topic of discussion among astronomers for decades. In an article published in The Astrophysical Journal, a team of astronomers presents new insights into this question.

the only binary that is seen separately

In the new study, a supermassive black hole Located within the binary elliptical galaxy B2 0402. +379. This is the only binary supermassive black hole The two objects have never been resolved in enough detail to be seen separately, and hold the record for the smallest separation ever measured directly: just 24 light years.

While this close separation predicts a powerful merger, later studies revealed that the pair has been stuck at this distance for more than three billion years, raising questions; What is support?

To better understand the dynamics of this system and its ongoing merger, the team examined archival data from Gemini North’s Gemini Multi-Object Spectrograph (GMOS), which allowed them to determine the motions of nearby stars. black holes,

“The excellent sensitivity of GMOS allowed us to map the stars’ increasing velocities when looking closer to the center of the galaxy,” Roger Romani, a Stanford University physics professor and co-author of the paper, said in a statement. “With this, we were able to estimate the total mass of black holes who live there.”

28 billion times that of the Sun

The team estimates the mass of the binary to be 28 billion times the mass of the Sun, making the pair eligible. black hole The most massive binary ever measured. This measurement not only provides valuable context for the formation of the binary system and the history of its host galaxy, but supports the theory that the mass of one black hole Supermassive binaries play an important role in preventing potential mergers.

Understanding how this binary forms can help predict whether it will merge or not, and a handful of clues point to the pair forming through the merger of multiple galaxies. The first is that B2 0402+379 is a “fossil cluster”, meaning it is the result of the merger of stars and gas from the entire galaxy cluster into one giant galaxy.

Furthermore, the presence of two supermassive black holeWith their large combined mass, this suggests that they were the result of the merger of many smaller black holes from multiple galaxies.

After the galactic merger, supermassive black hole They do not collide head-on. Instead, as soon as they settle into a confined orbit, they begin to cross each other. With each step they take, energy is transferred black holes To the surrounding stars. As they lose energy, the pair gets pulled closer and closer until they are only light years apart, where gravitational radiation takes over and they merge.

This process has been observed directly in pairs black holes of stellar mass (the first recorded case was through the detection of gravitational waves in 2015), but never in a binary of the supermassive variety.

With new insight into the extremely large mass of the system, the team concluded that it would take an exceptionally large number of stars to slow the binary’s orbit so close.

swept away with wires and gas

In this process, black holes They appear to have thrown away almost all the matter around them, leaving the galaxy’s core devoid of stars and gas. With no more material available to further slow the pair’s orbit, their fusion has stalled in its final stages.

“Generally it seems that paired galaxies black holes “Lighter stars have enough stars and mass to bring them together quickly,” Romani said. Because the pair is so massive, it would have required a lot of stars and gas to make it work,” he said. “But the binary has destroyed the central galaxy of so much material, making it stable for us to study.” And it has become accessible.”

Whether the pair will overcome their impasse and eventually merge on a time scale of millions of years, or remain stuck in orbital limbo forever, remains to be determined. If they merge, the resulting gravitational waves will be a hundred million times more powerful than those produced by fusion black holes of stellar mass.

It’s possible that the pair could conquer that final distance through another galaxy merger, which would inject the system with additional material, or potentially a third. black hole, slowing the pair’s orbit enough to merge. However, given B2 0402+379’s status as a fossil cluster, another galactic merger is unlikely.

“We hope to conduct a follow-up investigation of the core of B2 0402+379, where we will see how much gas is present,” says Tirtha Surti, a Stanford student and lead author of the paper. “This should give us more information about whether… supermassive black hole “They may eventually merge or remain trapped as binaries,” he said. (With information from Europa Press)