New findings imply that dark energy, the enigmatic force propelling the cosmos, is uniformly distributed throughout space and time.
The study team stated the findings also restrict dark energy’s share of the universe’s energy and stuff.
After reviewing eROSITA X-ray instrument data of galaxy clusters, which explore the whole sky over Earth for these rare galaxies, they came to their findings. Spektr-RG, a 2019 Russian-German space telescope, carries eROSITA.
Galaxy clusters help explain dark energy since this strange “anti-gravity” force should prevent massive cosmic structures from forming. Dark energy controls galaxy cluster formation.
“We can learn a great deal about the nature of dark energy by counting the number of galaxy clusters formed in the universe as a function of time,” study co-author Matthias Klein, an astrophysicist at Ludwig-Maximillians-Universitat Munchen in Germany (LMU), said in a statement(opens in new tab).
eROSITA Final Equatorial-Depth Survey (eFEDS) revealed 500 low-mass galaxy clusters. Clusters span around 10 billion years of the 13.8 billion-year-old universe’s history.
The study team merged the eROSITA observations with optical data from the Hyper Suprime-Cam Subaru Strategic Program. The first cosmology investigation used eROSITA galaxy clusters.
After comparing the study’s findings to theoretical projections, dark energy made up 76% of the universe’s energy density. This energy density seems to be constant and homogeneous in space and time.
Previous galaxy cluster investigations and weak gravitational lensing studies align with the team’s dark energy findings. While the latest results illuminate dark energy, physicists still want to understand it.
Why is dark energy so problematic?
In the 1920s, American astronomer Edwin Hubble made observations of distant galaxies that showed they are receding from us. Scientists discovered that the universe is expanding because distant galaxies move faster.
This upended the then-prevailing belief that the cosmos was stable. In 1998, distant supernovas revealed that the cosmos is expanding and speeding.
“To explain this acceleration, we need a source, and we refer to this source as ‘dark energy,’ which provides a sort of ‘anti-gravity’ to speed up cosmic expansion,” said research co-author Joe Mohr, an LMU astronomer.
Despite knowing what dark energy does and calculating that it makes up 76% of the universe’s energy and matter, scientists don’t know what it is or why it started acting on the universe in later epochs.
After the Big Bang ended, dark energy caused the cosmos to accelerate, like pushing a child on a swing. Without any force, the swing speeds up as the youngster slows down. Not only that, but it accelerates quicker and faster and reaches even higher heights.
Like the swing analogy, the accelerating expansion of the universe indicates that scientists are missing something.
“Although the current errors on dark energy constraints are still larger than we would wish, this research employs a sample from eFEDS that, after all, occupies an area less than 1% of the full sky,” said Mohr. “The nature of dark energy has become the next Nobel Prize-winning problem.”