Supermassive black holes may conceal secrets about their predecessors. A new study proposes an innovative approach to unravel these mysteries. While stellar black holes are born from the collapse of large stars, supermassive black holes owe their gigantic size to much more complex processes.
Astronomers believe that the growth of these giants occurs not only through the absorption of gas and stars but also through a series of mergers of increasingly massive black holes. In a study published in
Astroparticle Physics, Imre Bartos and Oscar Barrera explore how the "offspring" black holes resulting from these mergers can carry information about the "parent" black holes.
Bartos' findings show that black holes born from collisions retain crucial information about their ancestors' properties, such as mass and spin. The latter, also known as angular momentum, could even reveal their formation and growth history.
Although described by physicist John Wheeler as devoid of any superficial characteristics, black holes can still reveal clues about their past through their spin. A black hole that has acquired a high rotational speed could have grown by absorbing gas or through previous collisions.
To conduct their study, Bartos and Barrera applied an advanced statistical technique called Bayesian inference. This method is particularly suitable in the current context where physicists use gravitational waves to analyze black hole mergers. Indeed, Bayesian inference allows combining observed data with pre-existing knowledge to estimate the properties of ancestral black holes. This approach thus improves the accuracy of conclusions drawn from the gravitational waves detected during merger events.
Recent observations suggest that "production lines" of black holes, where several successive mergers occur, could be common in the Universe. Bartos is thrilled by this cosmic investigation, comparing the hunt for traces left by previous generations of black holes to a genuine detective investigation.