A new theoretical study has proposed a natural explanation for how supermassive black holes –once described as “the most perfect macroscopic objects in the universe, the only elements in their construction are our concepts of space and time” –formed in the early Universe. The proposal is the existence of stable galactic cores –made of dark matter surrounded by a diluted dark matter halo –that become so concentrated once a critical threshold is reached that they collapse into supermassive objects.
Explains Early Existence Soon After Big Bang
This intrepid conjecture eliminates the need for rapid star formation” solving one of the biggest problems in the study of galaxy evolution today: how supermassive black holes observed as early as 800 million years after the Big Bang, could grow so quickly.
The Royal Astronomical Society reports that the international team found that rather than the conventional formation scenarios involving ‘normal’ matter, supermassive black holes could instead form directly from dark matter in high density regions in the center of galaxies, challenging the accepted model of baryonic matter – the atoms and elements that that make up stars, planets, and all visible objects – collapsing under gravity to form black holes, which then grow over time..
“This new formation scenario,” says Carlos R. Argüelles, the researcher at Universidad Nacional de La Plata and ICRANet who led the investigation, “may offer a natural explanation for how supermassive black holes formed in the early Universe, without requiring prior star formation or needing to invoke seed black holes with unrealistic accretion rates.”
Dwarf Galaxy Dark Matter Mimics Conventional Central Black Holes
Another intriguing consequence of the new model is that the critical mass for collapse into a black hole might not be reached for smaller dark matter halos, for example those surrounding some dwarf galaxies, leaving smaller dwarfs with a central dark matter nucleus rather than the expected black hole. Such a dark matter core could still mimic the gravitational signatures of a conventional central black hole, whilst the dark matter outer halo could also explain the observed galaxy rotation curves.
Dark-Matter Haloes Key
“This model shows how dark matter haloes could harbor dense concentrations at their centers, which may play a crucial role in helping to understand the formation of supermassive black holes,” added Carlos.
“Here we’ve proven for the first time that such core-halo dark matter distributions can indeed form in a cosmological framework, and remain stable for the lifetime of the Universe.”
The authors hope that further studies will shed more light on supermassive black hole formation in the very earliest days of our Universe, as well as investigating whether the centers of non-active galaxies, including our own Milky Way, may play host to these dense dark matter cores.
Image at top of page: Discovery made with the Atacama Large Millimeter/submillimeter Array (ALMA) of a massive rotating disk galaxy, the Wolfe Disk, is seen when the Universe was only ten percent of its current age, challenges the traditional models of galaxy formation.