Astronomers do not have to wait too long until they can see for the first time one of the most gigantic mergers in space. The new study, chaired by Chiara Mingarelli, showed that gravitational waves emitted when two supermassive black holes collide can be detected in no more than 10 years. This study differs from others in that it uses real data, rather than the results of computer modeling.
Supermassive black holes are located in the centers of large galaxies, similar to our Milky Way, and their masses can reach several million or even billions of solar masses. For comparison, the masses of merging black holes, discovered so far with the help of gravitational-wave detectors, amounted to only a few dozen solar masses.
Although gravitational waves radiated by collisions of supermassive black holes are very powerful, they are not included in the wavelength range observed with the help of modern LIGO and Virgo experiments. In the future, stars will be used to search for gravitational waves emitted by combining supermassive black holes, called pulsars, which can be likened to cosmic “metronomes”. These rapidly rotating stars emit pulses of radio emission at a constant frequency. When a gravitational wave passes through the space between the Earth and the pulsar, the time between the arrival of individual pulses will slightly increase or decrease.
In their study, Mingarelli and her colleagues estimated the probability of finding a fusion of supermassive black holes, using data on the number of nearby galaxies in which black holes can be located, and data on the number and location of nearby pulsars. The results of calculations showed that convincing detection of gravitational waves coming from the collision of supermassive black holes can be done no more than 10 years, according to the authors of the study.