Black hole mergers are both beautiful and one of the most violent events in the universe. The process unfolds as follows.
The story begins with two people black hole They orbit far apart from each other in long lazy circles. They may have originated as a pair of binary stars, or they may simply have met by chance in the depths of the star. interstellar space. In any case, in order to merge, the two must get close together, which means losing a lot of orbital energy.
The first step in stealing energy from the system is through the interaction of the black hole with its environment. they are not alone. There is always a thin layer of gas and dust floating around. Sometimes there are even larger objects like planets or planets. star. All these objects are gravity Along with the black hole. Sometimes they fall off and are never seen again. Or it might pick up a little speed, steal some of its orbital energy from the black hole, and just barely miss.
When the black hole gets close enough, another process takes over. black hole disturbs space–time They orbit each other and are released by this stirring gravitational waves It emanates from the pair like ripples on a pond. However, gravitational waves are incredibly weak and only begin to seriously rob a black hole of energy if they get very close.
Related: How do dancing black holes approach and merge?
Because of this, astrophysicists were faced with a conundrum called “.final parsec problem” Simulations show that gravitational interactions with the environment can bring the black hole within about a meter. parsec (approx. 3.26 light years) each other within a considerable time. But within that distance, there just isn’t enough to keep the energy apart. On the other hand, at the same distance, gravitational waves are much too weak and take many times the time. age of the universe To get the job done.
The final parsec problem is currently an unsolved mystery. astrophysics. But whatever mechanism occurs, eventually the black holes will get close enough that gravitational waves can actually extract large amounts of energy from the system. At this point, the black holes have only a few seconds to merge.
At such close distances, black holes begin to deform each other. There is actually no surface. The event horizon is an invisible border that marks an area from which there is no escape. However, its shape is event horizon It depends not only on the black hole itself, but also on the geometry of spacetime around it. Therefore, when the black holes begin their deadly dance, their event horizons stretch toward each other.
We will only understand what happens next through complex computer simulations that monitor and track the evolution of the event horizon. A few milliseconds before impact, each black hole sends out a narrow tendril (a small tunnel in the event horizon) towards its companion star. These tendrils form a bridge between the two black holes, as if connected by an umbilical cord.
Soon the bridge widens and the event horizons come together like two soap bubbles colliding. In an instant, the black holes merge into one.
No one knows what’s going on inside. of center of black hole It is known as a singularity, or point of infinite density. This is where our current understanding of physics breaks down. Simulations show that the singularities quickly find each other, orbit for a short period of time, and then merge, but it is unclear what will actually happen.
Curiously, the mass of the newly merged black hole is less than the combined mass of the original black holes. For example, in 2016, Lygo scientific cooperation detected the first gravitational wave event From black hole mergers, scientists discovered that a black hole with a mass of 36 solar masses merged with a black hole with a mass of 30 solar masses, creating a new black hole with a mass of only 63 solar masses.
What happened to those three extra solar masses? That mass was converted into energy in the form of gravitational waves. Someone had to pay for all the energy loss, which resulted from the transformation of the black hole’s mass itself. Every time a black hole merges, approximately 5% is converted into gravitational waves.
From a perspective, it’s like converting three entire suns into pure energy. When black holes collide, they release more energy than all the stars in the universe, and it all happens in complete silence and darkness.
