Researchers have bolstered the theory that matter transforms into dark energy as massive stars undergo collapse and turn into black holes.
Nearly 14 billion years ago, during the very early moments of the Big Bang, an unknown energy caused an explosive expansion of the young universe, leading to the formation of all known matter, as suggested by the widely accepted inflationary universe model.
This ancient energy shared essential characteristics with today’s dark energy, which currently stands as one of the greatest mysteries of our time by at least one measurable standard: it constitutes about 70% of the universe, yet scientists remain uncertain about its true nature.
“If you ponder the question, ‘Where in the later universe do we observe gravity as intense as it was at the universe’s inception?’ the answer is at the core of black holes,” stated Gregory Tarlé, a physics professor at the University of Michigan and one of the study’s co-authors. “It’s conceivable that what transpired during inflation operates in reverse, where the matter of a gigantic star reverts to dark energy during gravitational collapse—similar to a miniature Big Bang happening in reverse.”
A new study released in the Journal of Cosmology and Astroparticle Physics by Tarlé and a team from five different institutions supports this hypothesis by utilizing recent findings from the Dark Energy Spectroscopic Instrument (DESI). DESI is composed of 5,000 robotic sensors affixed to the Mayall telescope located at the Kitt Peak National Observatory, which is situated on the territory of the Tohono O’odham Nation.
“If black holes contain dark energy, they can interact with and grow alongside the expanding universe, resulting in its accelerated growth,” noted Kevin Croker, the lead author of the study and an assistant research scientist at Arizona State University. “While we can’t delve into the specifics of this interaction, we can observe evidence that it is indeed occurring.”
The initial year of data from DESI’s five-year survey presents intriguing evidence suggesting that the density of dark energy has grown over time. The researchers view this observation as significant since it aligns with the pattern of increasing quantities and masses of black holes throughout cosmic history.
“When I first joined the project, I was quite skeptical,” commented co-author Steve Ahlen, an emeritus professor of physics at Boston University. “However, I kept an open mind throughout the entire process, and when we began performing the cosmological calculations, I thought, ‘This is a really interesting way to explain dark energy.’
The impact of DESI
To find support for dark energy originating from black holes, the team analyzed data from tens of millions of distant galaxies measured by DESI. This instrument looks billions of years into the past to collect data that enables precise calculations of the universe’s expansion rate. In turn, these findings can help determine how dark energy levels change over time.
The researchers compared this information with the frequency of black holes formed from the deaths of massive stars throughout the universe’s history.
“The two phenomena matched up well—new black holes formed from the demise of massive stars corresponded with an increase in dark energy in the universe,” said Duncan Farrah, an associate professor of physics at the University of Hawai’i and a co-author of the study. “This makes it more plausible that black holes could be a source of dark energy.”
This investigation adds to a growing assortment of research exploring the possibility of a connection between black holes and dark energy. A 2023 study, which included several authors from the current paper, reported on the potential interrelation of dark energy with supermassive black holes located in the centers of galaxies. This earlier study spurred other teams to look for similar correlations in black holes situated throughout varied locations in the universe.
“Those studies examined the relationship between dark energy and black holes based on their growth rates. Our new paper connects them through the timing of their formation,” explained Brian Cartwright, an astrophysicist and co-author who previously served as the general counsel for the U.S. Securities and Exchange Commission.
A notable difference in the new paper is that it focuses predominantly on younger black holes compared to those previously studied. These black holes were created during a time when star formation—interconnected with black hole formation—was already in progress rather than just commencing.
“This analysis occurs much later in the universe’s timeline and is informed by fresh observations of black hole production and expansion made with the Hubble and Webb space telescopes,” said co-author Rogier Windhorst, an interdisciplinary scientist for the JWST and a professor at Arizona State University.
“The next step is to determine where these black holes are located and how they have moved throughout the past 8 billion years. Scientists are currently working to narrow this down,” Croker mentioned.
Scientific exploration calls for a range of investigative paths and observations, and with DESI now operational, the quest to understand dark energy is just beginning.
“This will enhance our comprehension of dark energy and whether it continues to support the black hole hypothesis or not,” Ahlen remarked. “As an experimental initiative, it’s remarkable. You can hold preconceived notions or not, but our discoveries stem from data and observations.”
Regardless of the outcomes of future observations, the current work signifies a significant shift in dark energy research, the team stated.
“Essentially, the question of whether black holes are dark energy, linked to the universe they occupy, has transitioned from being a theoretical question to an experimental one,” Tarlé concluded.
