Dark Energy Effect on Large-Scale Structures in the Universe

Sunday - September 17 2023, 10:32 UTC - 1 year ago

Research from the University of Michigan has found that large-scale structures in the universe are expanding slower than previously expected, due to the attenuating effect of dark energy that is counteracting the forces of gravity. By studying how these structures have been clustering and growing, researchers can better understand the nature of gravity and dark energy.

Large cosmic structures are predicted to expand at a certain rate as the universe expands, with galaxy clusters and other dense areas expanding faster than empty space. Contrary to earlier understandings based on Einstein's theory of general relativity, research from the University of Michigan has now found that the pace of growth of these substantial structures is slower than expected.

A look into the anatomy of these structures shows that our cosmos is woven with galaxies like a vast cosmic spider web. They are not distributed randomly. Instead, they assemble in groups. In reality, the early universe's cosmic web began as small aggregates of matter that later developed into individual galaxies, galactic clusters, and filaments. Their study has been published in the journal APS.

Dark energy effect .

An initially modest mass draws and gathers more and more matter from its local area during the course of the universe through gravitational interaction. The area gradually collapses under its own gravity as it gets denser and denser.

According to the team, these clumps become denser as they crumble, which is described as growth in this reference. "It’s like a fabric loom where one-, two- and three-dimensional collapses look like a sheet, a filament, and a node. The reality is a mixture of all three cases, and you have galaxies living along the filaments while galaxy clusters—groups of thousands of galaxies, the most massive objects in our universe bounded by gravity—sit at the nodes," said Minh Nguyen, lead author of the study and postdoctoral research fellow in the University's Department of Physics.

The researchers claim that growth suppression is supported by both the Planck data on the cosmic microwave background and the data on the large-scale structure of galaxies, clusters of galaxies, and cosmic velocities.

Scientists highlight the relevance of dark energy in the universe's expansion. This mystery component aids in the expansion of the cosmos. However, dark energy has the opposite impact on big structures than it has on the universe's expansion. Dark energy works as an attenuator, dampening these perturbations and limiting the formation of structure. In contrast, gravity acts as an amplifier enabling matter disturbances to build into large-scale structures. "By examining how cosmic structure has been clustering and growing, we can try to understand the nature of gravity and dark energy, said Nguyen.

Cosmological probes .

The team utilized various probes to analyze the temporal growth of large-scale structures, starting with what’s termed as cosmic microwave background (CMB). This process is based on photons emitted just after the Big Bang, which provide a snapshot of the very early universe. Large-scale structures in their route may bend or gravitate the photons' course as they approach our telescopes. The distribution of structure and substance between our planet and the cosmic microwave background may be deduced by the researchers by looking at them.

"Crucially, as the CMB and background galaxies are located at different distances from us and our telescopes, galaxy lensing provides an integrated measure of the growth of structure along the line of sight over cosmic time," said co-author Jacob Hayden.