At some point we’ve all regretted taking too long to make a move on that special someone, but at least there’s comfort knowing we didn’t take a quarter of all time that’s ever passed. That’s how long the sexual tension has been building between two slow-dancing supermassive black holes, whose eventual congress could rock the entire universe.
Black holes get it on all the time, and who can blame them – they are, after all, so attractive that even the famously flighty light can’t say no. When two black holes are drawn into each other’s intense gravitational pull, they’ll tango for a few million years or so before coming together in cosmic coitus so powerful they become inseparable – literally, two become one.
For a long time, sweaty scientists only knew this from graphic textbooks. No matter where astronomers (read: pervs) pointed their telescopes, they just couldn’t see the action happening live – black holes either did it in the dark, or drew their dusty curtains first.
But in 2015, the celestially-frustrated scientists finally got lucky. They still couldn’t see it, but this time they picked it up like neighbors sharing a wall – through vibrations. Only instead of sounds keeping the next room awake, these were gravitational waves distorting the very fabric of spacetime itself, rippling out across the universe from that interstellar intercourse.
In the years since, astronomers have used their extremely sensitive equipment to hear hundreds of other cosmic couples getting freaky. In some cases they’ve even managed to watch, as bright neutron stars are a bit more exhibitionist about things.
Now, having exhausted all other voyeuristic ventures, astronomers are keen to watch some supermassive-on-supermassive action for the first time. These gigantic black holes can boast masses of millions or billions of Suns, and often lurk at the center of galaxies, including our own. It’s thought that they should also bump uglies like their smaller cousins, but because it’s never been seen directly scientists are starting to wonder if supermassive black holes are celestial celibates.
To find out, a team of astronomers have now taken a closer look at a pair of supermassive black holes in the galaxy B2 0402+379, which are looking particularly chummy. These two are just 24 light-years apart, which is pretty much second base in space terms – by comparison, the previous closest pair were in full priest garb at 1,600 light-years apart.
But, like awkward teens at a party, these two don’t seem to know what to do next. Previous studies have estimated that they’ve been stuck at this stage for about 3 billion years. To find out what’s with the infinite foreplay, the astronomers analyzed archival data from the Gemini North telescope, which allowed them to calculate the speed of embarrassed stars hurrying out of the area. This in turn let them estimate the total mass of the black holes.
They found that the binary packed a huge mass of about 28 billion times that of the Sun, making them comfortably the heaviest black hole pair ever measured so far. And from that, the scientists were able to infer some key details about the couple’s past – and potential future.
It seems that the black holes have come together because there are no other sexy singles in their area – B2 0402+379 is what’s called a “fossil cluster,” meaning a cluster of galaxies have all merged into one giant galaxy, so between the two remaining black holes, they’ve already hooked up with an entire cluster’s worth of other black holes.
Even with their dating options limited, they don’t just dive in. The black holes swing past each other a few times first, checking each other out, with each pass transferring some energy to the stars around them. As they lose energy, they begin to drift closer and closer together, until at a certain point their own gravitational influence takes over and they get jiggy with it.
But the bigger the supermassive black holes, the more wingmen you need to get them together. Because these two are the most massive binary pair recorded so far, the team concludes that a staggering number of stars would have been needed to get them this close together, but now it seems that their inappropriate actions have vacated the dance floor, leaving the pair in an awkward limbo for billions of years.
“Normally it seems that galaxies with lighter black hole pairs have enough stars and mass to drive the two together quickly,” said Roger Romani, co-author of the study. “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 and accessible for our study.”
So the ultimate question is, “will they or won’t they?” The researchers aren’t sure if the pair will ever get there on their own, but it could happen if they make like many stagnant couples and try to spice things up by bringing in a third black hole. The problem with that is that there aren’t any other nearby galaxies left to merge with.
If they do eventually get their happy ending, the climax will be felt across the universe – literally. The gravitational waves thrown off after that eternal edging would be 100 million times more powerful than any detected so far. And you can bet that those filthy astronomers will be waiting to listen in.
The research was published in The Astrophysics Journal.
Source: NOIRLab
