Science & Technology, UK (Commonwealth Union) – A novel approach for gauging dark energy, the enigmatic force constituting over two-thirds of the universe and driving its rapid expansion, has been uncovered by researchers within our own cosmic vicinity, specifically focusing on the Andromeda galaxy.
The team, hailing from the University of Cambridge, has proposed the prospect of detecting and quantifying dark energy by scrutinizing Andromeda, our galactic neighbor, as it gradually converges with the Milky Way in a slow-motion collision.
Historically, the study of distant galaxies has been the avenue to explore dark energy since its identification in the late 1990s. However, direct detection has remained elusive. The Cambridge researchers, however, have introduced a novel method: by dissecting the movement of Andromeda and the Milky Way as they mutually approach due to their combined mass, they were able to establish an upper boundary for the cosmological constant—the simplest form of dark energy. This recently determined elevated limit is 5 times higher than the cosmological constant’s value that can be deduced from observations of the early universe.
Though in its preliminary stages, this technique could potentially offer a means to unearth dark energy by focusing on our own cosmic neighborhood. The findings of this study are presented in The Astrophysical Journal Letters.
In the vast expanse of our world and celestial domain, encompassing everything from minuscule insects to immense galaxies, a mere five percent represents the observable realm. The remaining portion remains cloaked in darkness: roughly 27% is constituted of dark matter, responsible for gravitational cohesion, while a staggering 68% is occupied by dark energy, exerting the force to propel objects away from each other.
“Dark energy is a general name for a family of models you could add to Einstein’s theory of gravity,” explained 1st author Dr David Benisty from the Department of Applied Mathematics and Theoretical Physics. “The simplest version of this is known as the cosmological constant: a constant energy density that pushes galaxies away from each other.”
Initially, Einstein made a temporary addition of the cosmological constant to his general theory of relativity. From the 1930s until the 1990s, this constant was held at zero, until the revelation that an elusive force, known as dark energy, was driving the universe’s expansion to accelerate. However, grappling with dark energy presents two formidable challenges: its precise nature remains elusive, and direct detection continues to elude us.
Over time, astronomers have devised a range of techniques to detect dark energy, most involving the examination of ancient cosmic objects and quantifying their rate of recession. Yet, unraveling the influence of dark energy from eons past is intricate. Its impact, being a feeble force between galaxies, is readily overshadowed by the significantly more potent forces within galaxies.
Curiously, a specific realm within the universe displays remarkable sensitivity to dark energy – right within our cosmic vicinity. The Andromeda galaxy, situated closest to our Milky Way, is poised for a forthcoming collision. As the two galaxies converge, their interaction will initiate an exceedingly gradual orbital dance. A single orbit’s completion will span a staggering 20 billion years. Nevertheless, due to the immense gravitational forces at play, well in advance of a full orbit – around five billion years from now – the galaxies will commence a merger, embarking on a trajectory of mutual attraction and eventual convergence.
“Andromeda is the only galaxy that isn’t running away from us, so by studying its mass and movement, we may be able to make some determinations about the cosmological constant and dark energy,” added Dr Benisty, who is a Research Associate at Queens’ College as well.
The new findings in regards to Dark energy, are likely to make a significant contribution to astronomy in general, possible pointing to a new way of assessing outer space.
