Dance Giants of Death: Astronomers have discovered three supermassive black holes in the course of a collision – a real rarity. The gravitational giants are at the center of three merging galaxies. Their discovery provides a unique insight into the process of galaxies growing up and gigantic black holes appearing. Whether all three black holes eventually merge or one is ejected is still open.
In the center of almost all galaxies lies a supermassive black hole – also in the heart of our Milky Way. Only the enormous weight of these giants holds the galaxies together and shapes their behavior. But what happens when galaxies collide? The observations and models suggest that the black holes in their centers then merge with each other. However, there are also cases where the two gravitational giants still orbit each other for a surprisingly long time – thus the galaxy has two central black holes.
© NASA / CXC / George Mason Univ./ R. Pfeifle et al., SDSS and NASA / STScI
Three in one go
Why the Great Clash sometimes fails or at least delays, he wanted to examine Ryan Heifl George George Mason University in Fairfax and team closer. Therefore, in astronomical astronomy data, they first searched for fusion galaxies. They then directed the X-ray telescope to NASA's Chandra X-ray Department and the Large Binocular Telescope (LBT) in Arizona to assess the state of their active galactic nuclei.
Surprising result: In addition to some collisions of double-core galaxies, astronomers also discovered billiards, which included three galaxies. "We literally stumbled upon this incredible system," Pfeiffer says. Although telescopes have previously seen two of these galaxies, the third in the league has only just come to light. The triple system is located about one billion light-years from Earth and briefly bears the official name SDSS J084905.51 + 111447.2, SDSS J0849 + 1114.
Active galaxy cores in seam detail
The exciting question was: What about the central black holes of these three galaxies? The first indication was the images of the Chandra X-ray telescope. They detect three intense X-ray sources – clear signs of three supermassive black holes that actively capture matter. Additional LBT as well as infrared telescopes have also shown typical spectral signatures of absorbed matter in the vicinity of these objects.
"This is the strongest evidence to date of a triple system of active supermassive black holes," said Schiffle. According to telescope data, these active galactic nuclei are only between 11,000 and 23,000 light-years away. Larger quantities of gas and dust also indicate that they are already intensively interacting with each other, as astronomers report.
© Chandra X-ray Observatory
What about the trio?
But how does this scenario continue? As astronomers explain, two of the black holes will first merge. Because the presence of a third party in the league can bring a decisive pair of such galactic cores, a decisive impetus for definitive final access. "A third supermassive black hole can significantly shorten the time to fusion," explained Pifel and his colleagues. According to computer models, this trio effect can affect up to 16 percent of galaxy collisions.
However, the gravitational impact of the third black hole can have the opposite effect, as the researchers explain: Instead of giants getting closer to each other, the interactions act like a catapult and throw one of the three black holes away in space. "The result then in the galaxy was wandering a supermarket black hole," astronomers said. Researchers have already found evidence of such emissions in a distant quasar in 2017 – but in this case it was the result of a double collision.
To find out more about the interaction of active galactic nuclei, astronomers now want to look for other cases of such triple mergers. If different phases of these collisions are found, this may help to clarify the fate of such trips into the black hole. (Astrophysical Journal, in press)
Source: Chandra X-ray Observatory / Harvard-Smithsonian Astrophysics Center