Mark Megahan
The same philosophers who spend all night arguing drunkenly over how many angels can dance on the head of a pin have also been known to kick around the conundrum of what happens if an irresistible force encounters an immovable object. Two supermassive black holes on a guaranteed collision course provides pretty close to a textbook example of getting caught between a rock and a hard place. Even better, all the explosive action will be happening on astronomically cosmic scale. You may want to plan being elsewhere when the fireworks go off, in just about 250 million years or so.
Force fusion of Black Holes
At the center of most galaxies, including our very own Milky Way, you can find a black hole providing gravitational stability. Created from the collapse of only the most massive stars, the singularities continue to grow phenomenally more massive, as more matter falls past the point of no return, called the event horizon.
Because the inventor of the cat-flap, Isaac Newton, also happened to figure out that “force” is equal to “mass” multiplied by “acceleration,” we know that the two black holes will smack into each other like semi-trucks head-on at full-speed.
Astronomers lucky enough to book time at the Very Large Telescope at the European Southern Observatory captured images of the train wreck in progress. They also happen to be “the closest pair of supermassive black holes to Earth.”
That comes in handy for the number crunching experts. “The two objects also have a much smaller separation than any other previously spotted pair of supermassive black holes.” It is a total certainty that they’re on a collision course to “eventually merge into one giant black hole.” The force of the collision will be off the scale, even for astronomical events.
The singularities are speeding toward each other in the NGC 7727 galaxy which can be spotted if you point your telescope at the constellation Aquarius. It’s practically happening down the street. “the supermassive black hole pair is about 89 million light-years away from Earth.” Up until now, the closest pair we knew about was 470 million light-years away.
The force of gravity creates a dense group of stars in each nucleus with a supermassive black hole at its center.” They’re 1600 light-years apart and closing fast.
It happens all the time
Astronomers say this kind of thing is happening all the time. Pretty much any time two massive galaxies merge, sooner or later their black hole cores will spiral in closer to each other in a final dance of gravitational death force. What makes this pair so special is how close it is and how soon it will happen.
“The pair in NGC 7727 beat the record for the smallest separation between two supermassive black holes.” Not only are they merely 1600 light-years from each other, the “small separation and velocity of the two black holes indicate that they will merge into one monster black hole, probably within the next 250 million years.”
The experts nod their heads saying it explains “how the most massive black holes in the Universe come to be.” They know how to weigh black holes and some of them are huge. Karina Voggel and her team “were able to determine the masses of the two objects by looking at how the gravitational pull of the black holes influences the motion of the stars around them.”
Once they ran the calculations, the data confirms the “bigger black hole, located right at the core of NGC 7727, was found to have a mass almost 154 million times that of the Sun, while its companion is 6.3 million solar masses.” That means one heck of a lot of force when they collide.
Astronomers already have an example of what happens afterward. The host galaxy of the colliding pair NGC 7727 could itself be the “the result of a clash between two galaxies that occurred about one billion years ago.” They think it is because the “consequences of this tremendous cosmic bump are still evident in the peculiar, irregular shape of NGC 7727 and the streams of stars in its outer regions.”
The force of the collision is still having effects on surrounding space. The team wants to note that their “feat was made possible thanks to the close proximity of the system to Earth and the detailed observations the team obtained at the Paranal Observatory in Chile.”
