A groundbreaking new study reveals that the rotation curve of galaxies is flat all the way out to Earth, supporting the predictions of a modified theory of gravity that replaces dark matter.
This discovery calls into question existing cosmological models, suggesting that either the dark matter halo is significantly extended or that our understanding of gravity theory needs to be fundamentally reevaluated.
A Breakthrough in Cosmology
In a groundbreaking discovery that calls into question conventional understanding of cosmology, scientists from Case Western Reserve University have uncovered new evidence that could completely change our perception of the universe.
Tobias Mistere, a postdoctoral researcher in the Department of Astronomy at Case Western Reserve University’s School of Humanities and Sciences, has developed a groundbreaking technique called “gravitational lensing” to explore the mysterious realm of dark matter. He discovered that the rotation curve of galaxies is flat for millions of light years, with no end in sight.
Scientists have previously believed that the rotation curves of galaxies should decrease the further into the universe we look.
Challenging traditional cosmological models
Traditionally, the behavior of stars within the galaxy has puzzled astronomers. According to Newtonian gravity, stars at the outer edges of the galaxy should The reduction in gravity would cause the rotation to slow down. This was not observed, so the presence of dark matter was inferred. However, the dark matter halo would also disappear, so the rotation curve would not remain flat forever.
The Mistel analysis overturned this expectation and revealed a surprising fact: the influence of so-called dark matter extends at least a million light-years from the galactic center, far beyond previous estimates.
Such long-distance effects could indicate that dark matter as we understand it may not exist at all.
“This discovery calls into question existing models and suggests either that very widespread dark matter halos exist or that we need to fundamentally reassess our understanding of gravity theory,” he said.
Revolutionary impact on astrophysics
Stacey McGaugh, professor and chair of the Department of Astronomy in the College of Arts and Sciences, said Mistel’s research findings: Astrophysical Journal Letterspushing traditional boundaries.
“The implications of this discovery are profound,” McGough said, “not only will it redefine our understanding of dark matter, it will also inspire the search for alternative theories of gravity and challenge the very fabric of modern astrophysics.”
Overturning Einstein’s theory
Gravitational lensing, the main technique Mistere used in his study, is a phenomenon predicted by Einstein’s general theory of relativity. Essentially, gravitational lensing occurs when a massive object, such as a cluster of galaxies or a single massive star, bends the path of light coming from a distant source. This bending of light occurs because the object’s mass distorts the fabric of space-time around it. The bending of light by galaxies persists on much larger scales than expected.
As part of his research, Mistel plotted what’s called the Tully-Fisher relationship on a graph, highlighting the empirical relationship between a galaxy’s visible mass and its rotation speed.
“We knew this relationship existed,” Mistele said, “but it wasn’t clear that it would continue the further away it went. How far will this behavior go? That’s the question, because it can’t go on forever.”
Mistel said the discovery highlights the need for further exploration and collaboration within the scientific community, as well as analysis of other data.
Reassessing dark matter theory
McGaugh pointed to the monumental efforts, so far unsuccessful, by the international particle physics community to detect and identify dark matter particles.
“Either the dark matter halo is much larger than expected, or the whole paradigm is wrong,” McGough says. “The theory that predicted this behavior beforehand is MOND, a modified theory of gravity hypothesized by Moti Milgrom in 1983 as an alternative to dark matter. So the obvious and necessarily controversial interpretation of this result is that dark matter is a chimera, and the evidence for it probably points to a new theory of gravity beyond what Einstein taught us.”
Reference: “Indefinitely Flat Circular Velocities and the Baryonic Tully-Fisher Relation from Weak Lensing,” by Tobias Mistele, Stacy McGaugh, Federico Lelli, James Schombert, and Pengfei Li, accepted. Astrophysical Journal Letters.
arXiv:2406.09685