UH Manoa: Evidence of dark energy from black holes is growing: Maui now

Astronomy researchers have found new evidence that may help answer one of the biggest mysteries in the cosmos: where dark energy comes from. Data from their new experiment points to black holes.

Scientists believe that about 14 billion years ago, during the Big Bang, an unidentified energy caused the universe to rapidly expand and created everything we know. Today, a similar mysterious energy called “dark energy” still exists, which makes up about 70% of the Universe. But no one knows exactly what dark energy is or where it comes from.

The Big Bang began when ancient dark energy “decayed” into hot matter. Black holes appear to convert hot matter back into dark energy as if squeezing it together, almost like a mini Big Bang in reverse.

Scientists from five institutions, including the University of Hawaii at Manoa, revealed these results in a new study published in the journal Journal of Cosmology and Astroparticle Physics.

The findings are consistent with recent research that identifies dark energy with black holes based on their growth rate, while this study takes into account the timing of black hole formation.

According to the prevailing theory of the Inflationary Universe, nearly 14 billion years ago, at the very beginning of the Big Bang, mysterious energy caused the exponential expansion of the young Universe and produced all known matter.

This ancient energy shared key characteristics with the dark energy of the current Universe, which is the greatest mystery of our time by at least one objective standard: It makes up a large part—roughly 70%—of the Universe, but scientists don’t know exactly what. This.

“If you ask yourself the question, ‘Where in the later Universe will we see gravity as strong as it was at the beginning of the Universe?’ the answer lies at the center of black holes,” said Tarle, a professor at the University of Michigan and co-author of the study. “Perhaps what happened during inflation happens in reverse: the matter of a massive star becomes dark energy again during gravitational collapse—like a small Big Bang played out in reverse.”

A new study claims to strengthen the case for this scenario with recent data from the Dark Energy Spectroscopic Instrument (DESI): 5,000 robotic eyes mounted on the Mayall Telescope at Kitt Peak National Observatory on Tohono O’odham Nation land.

“If black holes contain dark energy, they could connect with and grow with the expanding Universe, causing its growth to accelerate,” said Kevin Crocker, lead author of the team’s new study, who is both a UH faculty member and research assistant. scientist at Arizona State University. “We can’t get the details of how this happens, but we can see the evidence. What this is happening.”

Data from the first year of the planned five-year DESI study show strong evidence that dark energy density is increasing over time. This provides a strong clue to support the idea of ​​what dark energy is, the researchers say, since the increase in time is consistent with how the number and mass of black holes increase over time.

“When I first started this project, I was very skeptical,” said Steve Allen, a Boston University professor and co-author. “But I kept an open mind throughout the process, and when we started doing cosmological calculations, I said, ‘Well, this is a really good mechanism for generating dark energy.’

The difference DESI makes

To find evidence of black hole dark energy, the team used tens of millions of distant galaxies measured by DESI. Looking back billions of years, this data can be used to determine the expansion rate of the universe with exceptional precision. In turn, this data can be used to infer how the amount of dark energy changes over time.

The team compared this data with how many black holes have formed as a result of the death of large stars throughout the history of the Universe. “The two phenomena were consistent with each other—as new black holes were formed by the death of massive stars, the amount of dark energy in the universe increased in the right way,” said Duncan Farrah, assistant professor of physics at the University of Hawaii and co-author of the study. “This makes it more likely that black holes are the source of dark energy.”

This research adds to the growing body of literature on the possibility of cosmological interactions in black holes. A 2023 study reporting the cosmological interaction of supermassive black holes in galactic centers, in which many of the authors of this paper contributed, has prompted other teams to look for the effect in black holes in all the different places where they can be found in the Universe.

“These papers explore the connection between dark energy and black holes through their growth rates. Our new paper links black holes to dark energy based on the time of their birth.” said Brian Cartwright, astrophysicist, co-author and former general counsel of the U.S. Securities and Exchange Commission.

The key difference in the new paper is that most of the corresponding black holes are younger than those previously studied. These black holes were born in an era when star formation, which tracks the formation of black holes, was already well underway, not just beginning.

“This occurs much later in the universe and is supported by recent measurements of black hole formation and growth observed with the Hubble and Webb Space Telescopes,” said Rogier Windhorst, co-author, James Webb Space Telescope interdisciplinary scientist and board member. and professor at Arizona State University.

Science demands more research and observation capabilities, and now that DESI is available online, dark energy research is just beginning. “The next question is where these black holes are and how they have moved over the last eight billion years. Scientists are working to limit this right now,” Crocker said.

“This will only bring more depth and clarity to our understanding of dark energy, whether it continues to support the black hole hypothesis or not,” Allen said. “I think as an experimental effort it’s great. You may or may not have preconceived notions, but we are guided by data and observation.”

Regardless of what these future observations bring, the work happening now represents a fundamental change in dark energy research, the team said.

“Essentially, the question of whether black holes are dark energy associated with the universe they inhabit is no longer just a theoretical question,” Tarle said. “This is an experimental issue right now.”