Almost every large galaxy in the Universe has a black hole roaring at its center (the Milky Way has Sagittarius A *). When two giant ellipticals merge, their black holes are expected to do the same, and a giant supermassive singularity occupies the center of the new galaxy – but astronomers do not know where the one that should occupy the center of the largest galaxy in the Abell 2261 cluster is. , 2.7 billion light years from Earth.
Black holes follow the size and mass of the host galaxy. The one at the center of Abell 2261 should weigh a hundred billion times the mass of the Sun (the mass of Sgr A * is four billion times that of our star); using data from NASA’s Chandra X-ray Observatory and the Hubble Space Telescope collected between 1999 and 2004, astronomers had predicted its existence.
When using 2018 Chandra observations to prove its existence, the surprise: there is nothing at the center of the galaxy. The team led by astronomer Kayhan Gultekin came to the most logical conclusion: what should be one of the largest black holes in the universe is simply not there.
Obviously, if it’s not there, it has to be somewhere – and this change of address could be the result of its ejection from the center of the new galaxy due to the process of merging between the two galaxies that collided.
The fusion of black holes is an event that generates an enormous amount of ripples in space-time. If more gravitational waves are propagated in one direction than in another, the new black hole will be sent away from the center of the galaxy in the opposite direction – generating what in cosmology is called a black hole reversal.