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A conceptual model centered on black holes transforming matter into dark energy provides a solution to gaps in our comprehension of the universe, including the mass of ethereal particles known as neutrinos
These are thrilling times to delve into the most significant unanswered queries in physics, aided by advanced experiments and highly accurate data. This is especially true regarding dark energy, the term given to the enigmatic force fueling the universe’s accelerating expansion.
In a publication in the Physical Review Letters, a coalition of researchers has unveiled fresh data bolstering the argument that the impact of dark energy on the cosmos—previously thought to be constant—is, in fact, evolving across cosmic timescales. The group and external partners illustrate how the data can be interpreted as an indication of matter transitioning into dark energy.
The new results originate from a remote mountain in southern Arizona known as Iolkam Du’ag. Here, the Tohono O’odham Nation oversees Kitt Peak National Observatory, where the Dark Energy Spectroscopic Instrument, or DESI, examines the universe’s history through 5,000 robotic eyes—each concentrating on a distinct galaxy every 15 minutes.
Operating nearly every hour of the night, DESI has already charted millions of galaxies and various types of ancient, radiant objects, many from a time when the universe was under half its current size.
In this latest study, the scientists concentrated on interpreting black holes as minuscule bubbles of dark energy. As black holes form when massive stars deplete their nuclear fuel and collapse, this cosmologically linked black hole, or CCBH, theory necessitates the conversion of stellar matter into dark energy.
This conveniently associates the rate of dark energy production, and matter consumption, with something that has been assessed for decades by the Hubble Space Telescope and now the James Webb Space Telescope: the rate of star formation.
“This study fits the data to a specific physical model for the first time, and it does so effectively,” stated DESI collaboration member Gregory Tarlé, professor emeritus of physics at the University of Michigan and the lead author of the latest report.
A primary emphasis of the research is the mass of ghost-like particles known as neutrinos, which are the second most prevalent particle in the universe. Scientists are aware that these particles possess masses greater than zero, thereby contributing to the overall matter composition in the universe, but their precise values remain unmeasured.
Interpreting the new DESI data through the lens of the CCBH model yields a measurement greater than zero, consistent with the current understanding of these ghost particles and an advancement over other interpretations that propose masses of zero, or even negative values.
“At the very least, it’s fascinating,” Tarlé remarked. “I would say engaging is a more precise term, although we typically reserve that in our discipline.”
Uendert Andrade, a Leinweber research fellow at U-M and co-director of DESI’s Year 3 Baryon Acoustic Oscillations analysis team, supplied data products and direction utilized in the latest report. The U-M authors of the study also featured Dragan Huterer, a physics professor, and Michael Schubnell, a research scientist.
DESI represents a global venture that unites over 900 scholars from more than 70 organizations. The initiative is directed by the Lawrence Berkeley National Laboratory, and the instrument was developed and is managed with backing from the U.S. Department of Energy Office of Science. DESI is positioned on the U.S. National Science Foundation’s Nicholas U. Mayall 4-meter Telescope at Kitt Peak National Observatory—a program from NSF NOIRLab—in Arizona.
Exorcising the Phantoms
The CCBH theory was proposed approximately five years ago by co-authors Kevin Croker, an assistant research scientist at Arizona State University, and Duncan Farrah, a professor at the University of Hawaii. For more than fifty years, mathematical representations of black holes as minuscule droplets of dark energy, instead of monstrous entities wrapped in impenetrable layers, have drawn the attention of researchers.
Nevertheless, the notion that the dark energy within such black holes might affect the universe as a whole was unconventional. Mathematically, however, it made sufficient sense to draw a small group of inquisitive researchers who began exploring how well the hypothesis aligned with observations and cosmological data.
“Traditionally, this is how physics is conducted. You propose as many concepts as you can and dismiss them as quickly as possible,” stated DESI researcher Steve Ahlen, an emeritus professor of physics at Boston University and an early contributor to the CCBH development.
“You shouldn’t shy away from innovative and distinct ideas, which is clearly what’s essential these days given the numerous mysteries we face.”
The initial data supporting the CCBH theory arose from the unforeseen growth of supermassive black holes at the centers of dormant elliptical galaxies in comparison to the growth of those galaxies’ stellar populations. However, it was the data from the initial year of DESI, which demonstrated that the density of dark energy tracked the rate of star formation, that led Croker and Farrah to collaborate with the DESI Collaboration.
“Working with DESI on the three-year data has been a transformative experience,” Croker remarked regarding his role as a DESI external collaborator on this project. “You have some of the most intelligent and innovative researchers in the field contributing their efforts. It’s a tremendous privilege.”
Aside from light packets known as photons, neutrinos are the most prevalent particles within the universe. During the time it takes to read this sentence, countless trillions of neutrinos will traverse your body. Yet, neutrinos rarely interact with their environment, meaning they move through other matter undetected, which is why they are often called ghost particles.
Researchers are aware that neutrinos possess mass, yet determining their exact amount remains challenging due to their elusive nature. While massive experiments currently underway on Earth strive to clarify these numbers, the night sky provides a potent and complementary pathway for solutions.
DESI’s galactic maps offer insights into how quickly the universe has expanded over the past 10 billion years, consequently furnishing a cosmic ledger of matter and dark energy. However, matter exists in three varieties: cold dark matter, baryons, and neutrinos. Early universe measurements taken from the aftermath of the Big Bang indicate the quantities of dark matter and baryons from eons ago. Still, according to DESI, it appears that there is less matter today compared to the distant past. This leaves minimal space for the neutrinos.
“The data implies that the neutrino mass is negative, which is undoubtedly unphysical,” commented Rogier Windhorst, Regents’ Professor at ASU’s School of Earth and Space Exploration and co-author of the recent study.
However, viewed through the lens of the CCBH theory, that unphysical problem vanishes. Since stars consist of baryons and black holes convert deceased stellar matter into dark energy, the current quantity of baryons has diminished relative to the Big Bang measures. This enables neutrinos to play a role in the matter budget as expected from other measurements.
“The probability distribution for neutrino mass indicates not just a positive value, but a figure that aligns perfectly with experimental findings on the ground,” Windhorst said. “I find this extremely exciting.”
CCBH: More Value for the Effort
While this finding takes center stage, it also emphasizes other beneficial attributes of the CCBH model.
“The CCBH theory quantitatively connects phenomena that one wouldn’t initially presume to be related,” Farrah stated. “It is the integration of scales, both large and small, which runs contrary to our inherently linear intuition.”
Matter slows down
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The expansion of the cosmos, while dark energy accelerates it. As matter transforms into dark energy in the CCBH theory, the accelerated expansion occurs sooner, leading to a somewhat higher expansion rate today, known as the Hubble constant. This additional boost aligns the cosmological estimate of the Hubble constant closer to other assessments, such as those derived from distant stellar explosions known as supernovae.
The CCBH theory further accounts for the detected quantity of dark energy: It’s not merely an arbitrary figure established at the universe’s inception. Dark energy originates from deceased stars; thus, it is nonexistent until stars exist, and stars only form when the universe has expanded to a significant size and temperature. Once stars emerge, the volume of dark energy produced is directly correlated with the number of stars formed.
“Engaging in this project has been both demanding and immensely enjoyable,” remarked study co-author Gustavo Niz, a researcher at the University of Guanajuato, Mexico. “This represents yet another step forward in validating CCBH as a plausible theory. More data, thorough analysis, and wider examination will be necessary to ascertain whether it can evolve into a new framework for elucidating our universe. Naturally, it could also be dismissed as fresh evidence arises.”
Croker mentioned that the hypothesis excels when assessing the universe in broad strokes, “but data from alternative experiments focusing on individual black holes isn’t as persuasive. This is what makes the hypothesis intriguing. Numerous observers can actively test it and refine it in real-time.”
According to Ahlen, that’s the nature of scientific inquiry. However, for researchers who have been involved with DESI since its inception, it’s exhilarating to observe that incoming data empowers scientists to evaluate new and varied hypotheses.
“This is truly amazing, to reach this stage after dedicating so much time to an experiment, to be generating thrilling results,” said Tarlé, who spearheaded the team that constructed DESI’s robotic observational system. “It’s simply fantastic.”
Alongside its primary backing from the DOE Office of Science, DESI also receives support from the National Energy Research Scientific Computing Center, a DOE Office of Science user facility. Additional assistance for DESI comes from the NSF; the Science and Technology Facilities Council of the United Kingdom; the Gordon and Betty Moore Foundation; the Heising-Simons Foundation; the French Alternative Energies and Atomic Energy Commission; the National Council of Humanities, Sciences, and Technologies of Mexico; the Ministry of Science and Innovation of Spain; and by the DESI partner institutions.
The DESI collaboration is privileged to be allowed to conduct scientific research on Iolkam Du’ag (Kitt Peak), a mountain of notable significance to the Tohono O’odham Nation.
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