As we gain greater ability to see deeper and deeper into the Universe, we’ve been finding something very surprising: Supermassive black holes millions to billions of times the mass of the Sun, before the Universe was even 10% of its current age.
This is quite the cosmological conundrum. Given what we all know about the expansion rate of black holes, there oughtn’t are enough time since Big Bang for them to grow so huge. But their presence is undeniable – so something strange must be afoot.
According to new research, that something could be one among the strangest things within the Universe : Dark-matter.
“We can consider two reasons why the early Universe black holes are so massive,” said physicist & astronomer Hai-Bo Yu of the University of California Riverside.
“The seed – or ‘baby’ – black-hole is either far more massive, or it grows much faster than we thought, or both. The question that then arises is what are the physical mechanisms for producing a huge enough seed black-hole or achieving a quick enough growth rate?”
Dark matter is one among the Universe’s greatest mysteries. we do not know what it’s , or what it’s made from . The sole way it interacts with the normal’ baryonic matter within the Universe – that is the stuff that each one the things we will see is formed of – is gravitationally.
Because it interacts gravitationally, we could observe gravitational effects within the Universe, like the rotation of galaxies and therefore the way light curves along a strong-gravitational-field , and subtract the gravitational effect of normal matter determine dark-matter content. and there is more of it. An estimated 85% of all the matter within the Universe is dark-matter .
Most galaxies reside in halo of dark-matter; it’s thought to be vital for their’ formation. One model for the formation of supermassive black holes is that the direct collapse of a dense cloud of gas. Yu and his colleagues wondered if there could be another contribution.
“This mechanism … cannot produce a huge enough seed black hole to accommodate newly observed supermassive black-holes – unless the seed black hole experienced a too fast rate of growth ,” Yu said.
“Our work provides an alternate explanation: A self-interacting dark-matter halo experiences gravothermal instability and its central region collapses into a seed black-hole .”
As far as we might tell thus far , dark-matter only interacts with baryonic matter gravitationally, but it’s going to be ready to interact with itself.
The team’s scenario starts with the formation of just such dark-matter halo, coming together gravitationally within the early Universe. The inward pull of gravity would compete against the outward push of warmth and pressure; for non-self-interacting substance , particles condensing towards centre of halo would speed up under the increasing gravity, and recoil under higher pressure, because they were unable to transfer their energy to other particles.
Self-interacting dark-matter-particles, however, would be ready to transfer energy to other particles, introducing friction to the rotating-dark-matter fluid. This is able to cause the particles to slow, reducing angular-momentum & shrinking the central halo in order that , eventually, it might collapse under its own mass to make the seed of a black-hole.
From now , the seed could grow by accreting baryonic matter, the researchers said. And, while the dark-matter ‘seed’ can have a high enough mass to permit black-hole to grow quickly, both sorts of matter are required.
“In many galaxies, stars and gas dominate their central regions,” Yu explained.
“Thus, it’s natural to ask how the presence of this baryonic matter affects the collapse process. We show it’ll speed up the onset of the collapse. This feature is strictly what we’d like to elucidate the origin of supermassive black holes within the early universe. The self-interactions also cause viscosity which will dissipate momentum of the central halo and further help the collapse process.”
The team hopes that future instruments, even more sensitive, are going to be ready to locate early Universe galaxies with range of brightnesses outside the capabilities of our current telescopes.
This should be ready to help validate their model, a result that wouldn’t just help us solve the matter of early Universe supermassive black holes, but the mysterious nature of dark-matter.
The research has been published in The Astrophysical Journal Letters.