Largest black hole collision

The largest collision of two black holes detected is the GW190521 collision between two black holes with estimated masses of 66 and 85 times the mass of the sun respectively, and was detected by LIGO (USA) and the Virgo Interferometer (Italy) on 21 May 2019.

The result of the collision was a larger, merged black hole, with a mass 142 times the mass of the sun. This is the first black hole between 100 and 100 thousand solar masses to have been detected, and suggests that supermassive black holes, like the one at the centre of our own milky way galaxy, may have formed through the repeated merging of smaller, stellar black holes.

The difference in mass between the two initial black holes and the resulting one was converted into an enormous amount of energy that was released as a huge explosion detected at both the Laser Interferometer Gravitational-Wave Observatory (LIGO) and the Virgo Interferometer in the form of gravitational waves. The collision took place so far away that even though gravitational waves travel at the speed of light, or approximately one billion kilometres per hour, it has taken more than seven billion years for the waves from this collision to be detected on earth.