Dark energy is a mysterious form of matter that makes up 70% of the mass of the Universe and shouldn’t be confused with dark matter. Unlike the latter, it doesn’t even manifest itself by gravitational influence, only through the expansion of the Universe. However, scientists have recently suggested that this mysterious thing may be related to black holes.
Dark energy and black holes
Nearly 14 billion years ago, at the very beginning of the Big Bang, a mysterious energy caused the young Universe to expand exponentially and created all the matter we know, according to the prevailing theory of an inflationary Universe.
This long ago energy possessed key features of the dark energy of the modern Universe, which is the biggest mystery of our time, at least by one objective standard: it makes up to 70% of its mass, but scientists don’t know exactly what it is.
“If you ask yourself the question, ‘Where in the later universe do we see gravity as strong as it was at the beginning of the universe?’ the answer is at the center of black holes,” said Gregory Tarlé, a University of Michigan physics professor and co-author of a new study on the mystery.
It is quite possible that what happened during inflation occurs in the opposite direction: the matter of a massive star becomes dark energy again during gravitational collapse – like a small Big Bang played in reverse.
In a new study published in the Journal of Cosmology and Astroparticle Physics, Tarlé and his colleagues from five institutions support the case for this scenario with recent data from the Dark Energy Spectroscopic Instrument (DESI). DESI consists of 5,000 robotic eyes mounted on the Mayall Telescope at Kitt Peak National Observatory.
Data from the first year of DESI’s planned five-year study indicate that the density of dark energy is increasing with time. According to the researchers, this provides strong evidence in favor of what dark energy is because this increase over time is consistent with how the number and mass of black holes have increased over time.
Research of black holes with the DESI instrument
To find evidence for the existence of dark energy from black holes, the team used tens of millions of distant galaxies measured by DESI. The instrument looks billions of years into the past and collects data that can be used to determine the rate of expansion of the Universe with extreme accuracy. In turn, this data can be used to conclude how the amount of dark energy varies with time.
The team compared this data to how many black holes have been formed by the deaths of large stars throughout the history of the Universe.
“The two phenomena were consistent with each other—as new black holes were made in the deaths of massive stars, the amount of dark energy in the universe increased in the right way,” said Duncan Farrah, associate professor of physics at the University of Hawaii and co-author of the study. “This makes it more plausible that black holes are the source of dark energy.”
This study complements a growing body of literature investigating the possibility of cosmological coupling in black holes. The 2023 study, which included many of the authors of this paper, reported cosmological coupling in supermassive black holes at galactic centers. The 2023 report encouraged other teams to look for this effect in black holes in all the different places they can be found in the Universe.
“Those papers investigate the link between dark energy to black holes by their rate of growth. Our new paper links black holes to dark energy by when they are born,” said Brian Cartwright, astrophysicist, co-author and former general counsel of the U.S. Securities and Exchange Commission.
Differences of the new study
A key difference in the new work is that most of the relevant black holes are younger than those studied previously. These black holes were born in an era when star formation – tracing the formation of black holes – was in full swing, not just beginning.
“This occurs much later in the universe and is informed by recent measurements of black hole production and growth as observed with the Hubble and Webb space telescopes,” said co-author Rogier Windhorst, a JWST interdisciplinary scientist and professor of Earth and space exploration at Arizona State University.
Science requires more ways to explore and observe, and now with DESI online, this exploration of dark energy is just beginning.
New insights into dark energy
“This will only bring more depth and clarity to our understanding of dark energy, whether that continues to support the black hole hypothesis or not,” Ahlen said. “I think as an experimental endeavor, it’s wonderful. You can have preconceived notions or not, but we’re driven by data and observations.”
No matter what these future observations bring, the work going on now represents a change in dark energy research. “Fundamentally, whether black holes are dark energy, coupled to the universe they inhabit, has ceased to be just a theoretical question,” Tarlé said. “This is an experimental question now.”
Provided by phys.org
