Using gravitational lensing, scientists have revealed that dark matter can extend more than a million light-years from the galactic centers, offering significant corrections to our gravitational theories, or the concept of dark matter itself. Credit: SciTechDaily.com
Groundbreaking new research reveals that the rotation curves of galaxies remain flat indefinitely far away, confirming the predictions of the modified theory of gravity as an alternative to dark matter.
This discovery challenges existing models of cosmology and suggests that either dark matter halos are significantly extended or our understanding of gravitational theory needs a fundamental reassessment.
A breakthrough in cosmology
In a breakthrough discovery that challenges the conventional understanding of cosmology, Case Western Reserve University scientists have discovered new evidence that could change our perception of the cosmos.
Tobias Mistele, a postdoctoral fellow in the Department of Astronomy at Case Western Reserve’s College of Arts and Sciences, is pioneering a revolutionary technique that uses “gravitational lensing” to delve into the enigmatic realm of dark matter. He discovered that the rotation curves of galaxies remain flat for millions of light-years with no end in sight.
Scientists previously believed that the rotation curves of galaxies should decrease the further you peer into space.
Modeling the weak rotation curve of lenses. Credit: Case Western Reserve University
A challenge to traditional space models
Traditionally, the behavior of stars in galaxies has puzzled astronomers. According to Newtonian gravity, stars on the outer edges Must to be slower due to the reduced gravitational pull. This was not observed, leading to the inference of dark matter. But even dark matter halos must disappear, so rotation curves must not remain flat indefinitely.
Mistele’s analysis defies this expectation, providing a startling revelation: the influence of what we call dark matter extends far beyond previous estimates, extending at least a million light-years from the galactic center.
Tobias Mistele. Credit: Case Western Reserve University
Such a long-range effect could indicate that dark matter – as we understand it – may not exist at all.
“This discovery challenges existing models,” he said, “suggesting that either significantly extended dark matter halos exist or that we need to fundamentally reevaluate our understanding of gravitational theory.”
Revolutionary implications for astrophysics
Stacy McGaw, professor and director of the Department of Astronomy in the College of Arts and Sciences, said Mistele’s findings, scheduled for publication in Astrophysical Journal Lettersexpand traditional boundaries.
“The implications of this finding are profound,” McGaw said. “Not only could this redefine our understanding of dark matter, but it also invites us to explore alternative theories of gravity, challenging the very fabric of modern astrophysics.”
Turning Einstein’s theory upside down
The main technique Mistele used in his research, gravitational lensing, is a phenomenon predicted by Einstein’s theory of general relativity. Essentially, this happens when a massive object, such as a galaxy cluster or even 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 spacetime around it. This bending of light by galaxies continues on much larger scales than expected.
Stacey McGough. Credit: Case Western Reserve University
As part of the study, Mistele plotted what is called the Tully-Fisher relation on a diagram to highlight the empirical relationship between a galaxy’s apparent mass and its rotation rate.
“We knew that connection existed,” Mistele said. “But it wasn’t obvious that the relationship would last the more you dated. How far does this behavior go? That’s the point, because it can’t go on forever.”
Mistele said his discovery underscores the need for further research and collaboration within the scientific community — and the possible analysis of other data.
A reappraisal of dark matter theories
McGaw noted the herculean — but so far unsuccessful — efforts in the international particle physics community to detect and identify dark matter particles.
“Either dark matter halos are much larger than we expected, or the whole paradigm is wrong,” McGaw said. “The theory that predicted this behavior beforehand was the modified MOND theory of gravity, hypothesized by Moti Milgrom as an alternative to dark matter in 1983. So, the obvious and inevitably controversial interpretation of this result is that dark matter is a chimera; perhaps the evidence for this points to some new theory of gravity beyond what Einstein taught us.
Reference: “Indefinitely flat circular velocities and the Tully-Fisher baryon connection from weak lensing” by Tobias Mistele, Stacey McGaw, Federico Lelli, James Shombert, and Pengfei Li, Accepted, Astrophysical Journal Letters.
arXiv: 2406.09685
