Astronomers find black holes created in mergers carry information about their ancestors

A recently published paper in Astroparticle Physics by Imre Bartos and Oscar Barrera from the Department of Physics at the University of Florida sheds light on how information about "parent" black holes can be carried by "daughter" black holes formed through mergers. While supermassive black holes at the centers of galaxies cannot be directly created by the collapse of a massive star, mergers of black holes of increasing size can contribute to their growth.

Traditionally, black holes possess few discernible characteristics other than mass, spin, and electric charge. This is known as the "no-hair theorem," elucidated by theoretical physicist John Wheeler. However, Bartos explains that despite this limitation, it is still possible to unravel details about a black hole's origins by examining its spin. For instance, high spin could indicate black holes that have accreted matter from their surroundings or have resulted from previous "parent" black hole collisions, while low spin is often associated with black holes born from star deaths and collapses.

Bartos and Barrera employed Bayesian inference, a mathematical technique, in their study. By incorporating measured black hole properties and their prior expectations, they were able to infer distributions of the ancestral black hole properties. This research is especially relevant as astronomers use gravitational wave observations, small ripples in spacetime, to gain insights into black hole mergers.

The paper's findings become significant in light of recent discoveries suggesting the prevalence of black hole assembly lines, where multiple black holes merge successively, resulting in more massive entities. This discovery poses the exciting challenge of determining the properties of ancestral black holes from the measurements of the newest generation. Bartos describes his fascination with this detective story, uncovering the secrets of these cosmic entities from their fingerprints left by previous generations.

In conclusion, the study by Bartos and Barrera highlights the potential of "daughter" black holes formed through mergers to carry information about their ancestral black holes. The spin of these black holes can offer valuable insights into their origins, shedding light on the mysteries of the universe. As astronomers continue to explore black hole collisions and mergers through gravitational wave observations, the tantalizing possibility of unraveling the story of ancestral black holes grows ever closer.