The Theory of Relativity predicted theory predicted black holes, neutron stars, and the gravitational waves from their mergers. Scientists finally observed these mergers and their gravitational waves in 2015. Since then, the LIGO/Virgo collaboration has detected many of them. The collaboration has released a new catalogue of discoveries, along with a new infographic. The new infographic displays the black holes, neutron stars, mergers, and the other uncertain compact objects behind some of them.
The infographic accompanies the new catalogue of gravitational waves and mergers published by LIGO/Virgo. The catalogue is called the GWTC-2, or Gravitational-Wave Transient Catalog-2. While the previous catalogue contained only 11 signals, this new one contains 50.
The signals come from all combinations of mergers between black holes and neutron stars. The new catalogue contains some surprises. A pair of the detections were from the mergers of low-mass objects.
“One of our new discoveries, GW190426_152155, could be a merger of a black hole of around six solar masses with a neutron star. Unfortunately the signal is rather faint, so we cannot be entirely sure,” explains Serguei Ossokine, a senior scientist at AEI Potsdam. “GW190924_021846 certainly is from the merger of the two lightest black holes we’ve seen so far. One had the mass of 6 Suns, the other that of 9 Suns. There are signals from mergers with less massive objects like GW190814 but we don’t know for sure whether these are black holes.”
On the surface of it, each of these events can appear similar. They’re all the result of mergers of black holes and/or neutron stars. But according to Frank Ohme, leader of an Independent Max Planck Research Group at AEI Hannover, observations are revealing more and more detail.
“When you look at the catalogue, there’s one thing all events have in common: They come from mergers of compact objects such as black holes or neutron stars. But if you look more closely, they all are quite different,” said Ohme. “We’re getting a richer picture of the population of gravitational-wave sources. The masses of these objects span a very wide mass range from about that of our Sun to more than 90 times that, some of them are closer to Earth, some of them are very far away.”
One of the highlights in the catalogue is GW190521, which is the most massive binary black hole merger with a total mass of 150 Suns and the first observation of the birth of an intermediate-mass black hole. Another is GW190425, which is most likely the second observation of a binary neutron star merger.