New Evidence Suggests Black Holes Might Be the Source of Dark Energy through ‘Cosmological Coupling’

A research team led by a University of Michigan physicist has found the first evidence for ‘cosmological coupling’ – a recently predicted phenomenon in Einstein’s theory of General Relativity that can only manifest itself if black holes are introduced into an expanding universe – within data obtained from cosmological surveys taken over the last 9 billion years. Supermassive black holes were studied at the core of old and inactive galaxies, using astronomy data observed in recent years, by constructing a description based on research conducted by Gregory Tarlé, a physics professor at the University of Michigan, with colleagues from the University of Hawaii and other universities in nine countries.

Their findings have been published in two scientific articles: The Astrophysical scientific and The Astrophysical Journal Letters. The first research revealed that these black holes grow mass over billions of years in a manner that cannot be fully explainable through the more common actions in galaxies and black holes such as mergers and gas accretion. As the second paper pointed out, these black holes have the mass growth rate that is precisely expected for black holes which cosmologically couple and are able to enclose vacuum energy – a substance created when matter is squeezed to the utmost limit without reaching singularity according to Einstein’s relativity.

As with singularities, therefore, the article shows that with the total vacuum energy in the black holes formed after the deaths of the first generation stars being equal to the amount of dark energy in the present universe. “We’re really saying two things at once: There is actually proof that most of black hole solutions are not suitable for you in an ultra-dictionary, and were the first astrophysical source of dark energy identified, commented Duncan Farrah the lead author of both papers and an astronomer at University of Hawaii. “What that means, though, is not that other people haven’t proposed sources for dark energy, but this is the first observational paper where we’re not adding anything new to the universe as a source for dark energy: Black holes are the dark energy in the Einstein’s theory of gravity.

If the above measurements are supported by more data, these measurements will alter our perception of what a black hole is.

Nine billion years ago

First, the researchers examined how the currently existing observations of black holes can be employed to look for cosmic entanglement. “This provided my interest on this project more like a general inclination in lieu of trying to find what observational evidence supports any model for black holes that holds water no matter how long you observe them,” Said Farrah. “This is a very, very difficult thing to do in general,” explains Kulkarni, “because black holes are very small, very difficult to see directly, and very far away”.

They are just as challenging to observe in space over such durations as well as are black holes . Moreover, observations can take an instant or can span tens of years, which is not enough time to understand how a black hole may evolve throughout the existence of the universe. While it is relatively easy to comprehend that black holes exist and how they may behave in the immediate future, it is far harder to ascertain how they change across the billions of years. “You would first need to find out how many black holes there were billions of years ago and determine their mass” Then, one has to find that same population or a related population today and measure their mass once again,” said Tarlé.

“It must be so hard to get to that point. ”Since galaxies are known to live billions of years and the majority of them contain a quasar, the researchers came to understand that to get the answer, one had to select the right sort of galaxies.

Originally, scientists did not have a clear idea of what black holes in galaxies could do: “There were many points of black hole behaviors in galaxies reported in the literature, but there was really no standard,” as commented by the co-author of the paper, Sara Petty who is a galaxy expert at NorthWest Research Associates.

It was on this premise that we proposed that if we were to study only the black holes most galaxies which are black holes are in; passively evolving elliptical galaxies, then we could possibly contribute to sorting out this issue.

Elliptical galaxies are massive and formed early. They resemble remains of galaxy construction. Astronomers believe they are the end consequence of galaxy mergers, behemoths composed of billions of ancient stars.

“These galaxies are old, don’t produce many new stars, and have very little gas remaining between them. Tarlé replied, “There is no food for black holes.”

By focusing primarily on elliptical galaxies with no recent activity, the researchers could argue that any variations in the galaxies’ black hole masses could not be easily explained by other known processes. Using these populations, the scientists investigated how the mass of their center black holes has evolved over the last 9 billion years.

If black hole mass development happened only through accretion or merging, the masses of these black holes would be anticipated to remain relatively constant. However, if black holes gain mass by interacting with the expanding cosmos, these passively developing elliptical galaxies might disclose this process.

The researchers discovered that the further back in time they examined, the smaller the black holes were in mass compared to their masses today. These changes were significant: black holes were 7 to 20 times bigger now than they were 9 billion years ago, leading the researchers to hypothesize cosmic coupling.

Unlocking black holes

in the second exploration, the team investigated if the increase in the number of black holes identified in the first survey could be caused solely by cosmic coupling. ‘This is a toy analogy. ’Kevin Croker, a theoretical astrophysicist at the University of Hawaii and a co-author of the study, compared a connected black hole to a rubber band that is stretched as the universe expands. “It also increases its energy as it expands.

Continuing the formula of Einstein E=mc2 where mass and energy are proportional, the mass of the black hole also increases. The extent by which the mass rises depends on the coupling strength that the researchers denote by k. “The firmer the rubber band, the more resistant it will be and the more energy it will take to pull it and stretch it; In a word that is okay,” Croker opined. Since the mass production of black holes due to cosmic coupling is directly proportional to the size of the universe and was less in size in the past, to make the cosmological coupling theory fit, the black holes in the first study must be less in mass by the required amount.

The researchers examined five distinct black hole samples in three categories of elliptical galaxies from the time when the universe was fifty to thirty percent of the current age. In each comparison, they noticed that k was nearly equal to 3. Croker, at the time a doctoral student, and Joel Weiner, a mathematics professor at the University of Hawaii, expected this number for black holes with vacuum energy instead of a singularity four years ago.

The result is profound: Croker and Weiner had shown before that if k is equal to 3, then all black holes in the universe produce a reasonably constant density of dark energy at the moment as global measurements suggest.

“Is it enough?” Tarlé asked. “Is the formation of black holes over time significant enough for them to provide 70 % of energy of today’s universe?”Black holes are born from dying huge stars, so if you know how many big stars you are churning out, you can deduce how many black holes you are synthesizing and how much they are growing thanks to the cosmic coupling. By substituting the current measurements of the rate of early star formation provided by the James Webb Space Telescope into the formula, the team found that the numbers add up.

In the words of the researchers, it provides a framework for theoretical physicists and astronomers to further explore it and also empowers the current generation of the dark energy experiments including DES and DESI to elucidate the notion.

“If cosmological coupling is real, then black holes remain linked with the universe, and thus form a powerful force shaping the future evolution of the universe” Tarlé said. Apparently, there is no explanation in today’s physics for what dark energy is: “It is probably the biggest mystery of the universe – it is 70% of all of energy out there – and now we know where it comes from, why it is 70% and why it is here right now!”

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