It is quite rare to spot a black hole in space, let alone spot a black hole collision which in itself is an epic spectacle of the universe. But before we look into the details of a black hole collision, it’s useful to understand what black holes are.
Owing to a strong gravitational force, a black hole is a region in space that sucks matter in its vicinity. In fact, the gravitational force is so strong that even light cannot escape from it. Hence the title black hole. As far as the birth of black holes are concerned. They are usually formed when two or more gigantic stars approaching the end of their life cycles collide. Upon collision, a black hole is born that grows exponentially by absorbing the particles and other matter around it. Such is the complexity and beauty of the universe of which we form a tiny part of.
To imagine a merger containing two black holes, with one black hole at least the size of approximately 85 suns is, as Simon Portegies Zwart; computational astrophysicist at Leiden University, put it “mind boggling”. The merger that left the astronomers in awe also presented the astronomers with a revelation that the collision of black holes produces yet again another black hole, but only bigger and stronger. The black hole produced due to the merger in discussion is said to be as large as 150 solar masses.
Thanks to the cutting edge technology used by the US and an Italian observatory, the detection of this colossal merger was possible from almost 7 billion light years away. The discovery was made by recording the sudden spike in gravitational waves which are indicative of any activity occurring in space. In a collision of cosmic matter, energy is released in the form of gravitational waves which are then recorded by astronomers to detect the event taking place far away in the galaxy. But when it comes to this merger, the spike in gravitational waves awed the astronomers and for every right reason. Just spotting a black hole is rare enough, now imagine a collision between two.
What makes this merger mind boggling for the astronomers is the sheer size of the black holes involved in the collision. Since theoretically speaking, it is highly unlikely for stars of such giant sizes to exist. Therefore, a black hole which is a product of two or more stars colliding, existing with such a heavy mass is also unlikely-but not impossible as the merger shows.
Astronomers are putting forward all sorts of theories to explain the gigantic size of the black holes involved in the merger, some suspects the black holes to be a product of multiple smaller black holes.
How a black hole so huge came into existence is still puzzling and unknown to the astronomers but this merger nonetheless puts in perspective just how spectacular our universe is.