Astronomers suggest that at the center of most, if not all, galaxies is a supermassive black hole with a mass of millions or even billions of times the mass of our Sun. These massive objects cannot form directly from the collapse of a massive star, as is the case with stellar-mass black holes, because no star is massive enough to give rise to such magnificent structures.

Therefore, there must be processes that will enable black holes to reach such huge masses. The accretion of surrounding gas, dust, and even stars can contribute to this growth, but the fastest way to increase mass is through successive mergers of increasingly larger black holes.

In a paper published in the journal Astroarticle Physics, authors Imre Bartos and Oscar Barrera from the University of Florida describe how “sister” black holes formed in such a merger can store information about the enraged “parent.”

“We found that black holes that emerge from the merger of other black holes carry information about the properties of their ‘ancestors’, such as spin and mass,” says Bartos. The most important innovation in the field of research is the reconstruction of the spin of “parent” black holes based on data obtained on their masses.

The properties of black holes are limited: it is only possible to measure mass, angular momentum (spin) and electric charge. However, according to Bartos, even these few parameters are enough to reconstruct some details about the origin of the black hole. For example, high spin may indicate accretion of surrounding gas or previous mergers of “parent” black holes, while low spin often accompanies the birth of a black hole during the gravitational collapse of a star.

In their study, Bartos and Barrera used the Bayesian mathematical method, which reconstructs the properties of parent objects by matching the measured properties of a black hole with expected parameters. This work is extremely important as physicists increasingly use gravitational waves to study black hole collisions and mergers.

“Recent observations of black hole mergers suggest that black hole ‘merger lines’, in which multiple objects merge sequentially, may be a common phenomenon in the universe. In this context, the question arises of how we can restore the properties of ancient black holes based on measurements of their descendants. Space objects “I was fascinated by this detective story about uncovering the past and discovering the legacy of previous generations,” says Bartos.