Research that can reshape our perception of the cosmos has corroborated the predictions of the modified theory of gravity as an alternative to the presence of dark matter.
Scientists at Case Western Reserve University have discovered that the rotation curves of galaxies remain flat for millions of light years with no end in sight. It was previously believed that the rotation curves of galaxies must decline the further out into space you look.
Postdoctoral researcher Tobias Mistele pioneered a revolutionary technique that uses “gravitational lensing” to delve into the enigmatic realm of dark matter.
Traditionally, the behavior of stars within galaxies has baffled astronomers. According to Newtonian gravity, stars at the outer edges should be slower due to decreased gravitational pull. This was not observed, leading to the inference of dark matter. But even dark matter halos should end, so the rotation curves should not remain flat indefinitely.
Mistele’s analysis challenges this expectation, providing a surprising 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.
Such a far-reaching effect may indicate that dark matter, as we understand it, might not exist at all.
“This finding challenges existing models,” he said, “suggesting that either enormously widespread dark matter halos exist or that we need to fundamentally reevaluate our understanding of gravitational theory.”
Stacy McGaugh, professor and chair of the Department of Astronomy in the College of Arts and Sciences, said Mistele’s findings, scheduled to be published in the Astrophysical Journal Letters, push traditional boundaries.
“The implications of this discovery are profound,” McGaugh said in a statement. “Not only could it 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 UP
The main technique Mistele used in his research, gravitational lensing, is a phenomenon predicted by Einstein’s theory of general relativity. Basically, it occurs 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 mass of the object warps the structure of space-time around it. This bending of light by galaxies persists on much larger scales than expected.
As part of the research, Mistele plotted what is called the Tully-Fisher relation on a graph to highlight the empirical relationship between a galaxy’s visible mass and its rotation speed.
“We knew this relationship existed,” Mistele said. “But it wasn’t obvious that the relationship would persist the further away you go. How far does this behavior persist? That’s the question, because it can’t persist forever.”
Mistele said their discovery underscores the need for further exploration and collaboration within the scientific community, and possible analysis of other data.
McGaugh highlighted the Herculean, though so far unsuccessful, efforts of the international particle physics community to detect and identify dark matter particles.
“Either the dark matter halos are much larger than we expected, or the whole paradigm is wrong,” McGaugh said. “The theory that predicted this behavior in advance is the modified MOND theory of gravity, hypothesized by Moti Milgrom as an alternative to dark matter in 1983. Therefore, the obvious and inevitably controversial interpretation of this result is that dark matter “It’s a chimera; perhaps the evidence for it is pointing to some new theory of gravity beyond what Einstein taught us.”
