New study suggests supermassive black holes may arise from dark matter

A new theoretical study has proposed a new mechanism for creating supermassive black holes from dark matter. The international team finds that instead of the conventional formation scenarios with ‘normal’ matter, supermassive black holes can instead arise directly from dark matter in areas of high density in the centers of galaxies. The result has important implications for cosmology in the early Universe and has been published in Monthly Communications from the Royal Astronomical Society

Exactly how supermassive black holes were initially formed is one of the biggest problems in the study of the evolution of galaxies today. Supermassive black holes have been observed as far back as 800 million years after the Big Bang, and how they grew so quickly remains unexplained.

Standard formation models involve normal baryonic matter – the atoms and elements that make up stars, planets, and all visible objects – that collapse under gravity to form black holes, which then grow over time. However, the new work explores the potential existence of stable galactic nuclei made of dark matter and surrounded by a dilute dark matter halo, finding that the centers of these structures can become so concentrated that they can also collapse into supermassive black holes. , once a critical threshold. has been reached.

According to the model, this could have happened much faster than other proposed formation mechanisms and supermassive black holes in the early Universe could have formed before the galaxies in which they live, contrary to current views.

Carlos R. Argüelles, the researcher at Universidad Nacional de La Plata and ICRANet who led the study, notes: “This new formation scenario may provide a natural explanation for the way supermassive black holes formed in the early Universe, without prior star formation. or that evoke black holes with unrealistic accretion rates. “

Another intriguing consequence of the new model is that the critical mass for collapse into a black hole may not be reached for smaller halos of dark matter, such as those around some dwarf galaxies. The authors suggest this could then leave smaller dwarf galaxies with a central dark matter nucleus in place of the expected black hole. Such a dark matter nucleus could still mimic the gravitational signatures of a conventional central black hole, while the outer halo of dark matter could also explain the observed galaxy rotation curves.

“This model shows how dark matter halos can harbor dense concentrations at their centers, which may play a critical role in helping us understand supermassive black hole formation,” added Argüelles.

“Here we proved for the first time that such distributions of dark matter between the nucleus and the halo can indeed form in a cosmological framework, and remain stable over the lifetime of the Universe.”

The authors hope that further studies will shed more light on the formation of supermassive black holes in the very first days of our Universe, and that they will investigate whether the centers of inactive galaxies, including our own Milky Way, can host these dense dark matter nuclei.