Black holes collide: Researchers see flash of light for the first time

Black holes are black. The gravity is so strong that not even visible light can escape.

Accordingly, it is a rather dark affair when this cosmic event happens: the collision and merging of two black holes. Researcher want to have discovered a flash of light in such an event for the first time.

Shock waves

The whole thing happened 7.5 billion light years from Earth. Two black holes rotated several times a second before hitting each other. The explosion launched shock waves into space. And that could have been the trigger for the flash of light.

At their last dance, the black holes were in a huge disk of dust and gas. This disk is several light years in size and surrounds another black hole. It is a supermassive black hole in the center of the galaxy. This galactic construct of disk and active, supermassive black hole is called quasar.

Rotating the smaller black holes and the collision hurled the aforementioned shock waves into the gas and dust. As a result, the material heated up, became lighter and could be seen from the earth. For the scientists, it was a case of black holes being “at the right time, in the right place.”

Unconventional theory

However, the discovery was not accidental. The researchers behind it wanted to know why quasars sometimes flash inexplicably, i.e. shine much brighter for a short time. They theorized that black holes near a quasar could be responsible. However, the quasar itself is a supermassive black hole. The idea of ​​smaller black holes in the center of a galaxy, next to a supermassive black hole, was very unconventional.

Nevertheless, they pursued the theory. They used the measurements of the Ligo and Virto observatories. These have specialized in detecting gravitational waves that travel through space at the speed of light. These arise, among other things, when black holes merge.

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