International research by more than 100 astrophysicists shows how space has been expanding over the past 11 billion years.
The Sloan Digital Sky Survey (SDSS) released on Monday (20) an analysis of the largest three-dimensional map of space ever created, filling some of the most significant gaps in the history of our universe.
The new results come from the Baryon Oscillation Spectroscopic Survey (eBOSS), an international collaboration of more than 100 astrophysicists that is part of the SDSS.
“Taken together, detailed analyses of the eBOSS map and the earlier SDSS experiments have now provided the most accurate expansion history measurements over the widest-ever range of cosmic time,” eBOSS researcher Will Percival said in a statement. “These studies allow us to connect all these measurements into a complete story of the expansion of the universe.”
According to scientists, the map reveals the filaments and voids that define the structure of space since it was only 300,000 years old.
The method also allowed researchers to measure patterns in the distribution of galaxies, providing several key parameters of our universe with accuracy greater than 1%.
Expansion of the universe
The cosmic history revealed on the map shows that, about six billion years ago, the expansion of the universe began to accelerate, getting faster and faster since then.
The responsible for this is an invisible component known as dark energy.
However, the new measurement reveals that the current rate of expansion of the universe (the Hubble constant) is about 10% lower than the value calculated from the distance of nearby galaxies.
There is no widely accepted explanation, but a hypothesis indicates that a form of matter or energy from the early universe is responsible for this difference.
To create the map, scientists divided into different groups and each focused on a type of object, from red and blue galaxies to quasars.
More than two decades of research have resulted in 20 articles published so far.
“By combining SDSS data with additional data from the Cosmic Microwave Background, supernovae, and other programs, we can simultaneously measure many fundamental properties of the universe,” explained Eva-Maria Mueller, a senior researcher at the University of Oxford who led the SDSS analysis. “The SDSS data cover such a large swath of cosmic time that they provide the biggest advances of any probe to measure the geometrical curvature of the universe, finding it to be flat. They also allow measurements of the local expansion rate to better than one percent.”