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Geneva (AFP)
Astrophysicists released the largest 3D map of the Universe on Monday, the result of an analysis of more than four million ultra-bright and energetic quasars and galaxies.
The efforts of hundreds of scientists from around 30 institutions worldwide have produced a “complete history of the expansion of the universe,” said Will Percival of the University of Waterloo in Ontario, Canada.
In the project launched more than two decades ago, the researchers made “the most accurate measurements of the expansion history in the widest range of cosmic time,” it said in a statement.
The map is based on the latest observations from the Sloan Digital Sky Survey (SDSS), titled “Extended Baryon Oscillation Spectroscopic Study” (eBOSS), with data collected from an optical telescope in New Mexico over six years.
The infant universe that follows the Big Bang is relatively well known through extensive theoretical models and observation of the cosmic microwave background – electromagnetic radiation from the rising cosmos.
Galaxy studies and distance measurements also contributed to a better understanding of the expansion of the Universe over billions of years.
– ‘Problematic gap’ –
But Kyle Dawson of the University of Utah, who released the map on Monday, said the researchers addressed a “problematic gap in the middle of 11 billion years.”
Through “five years of continuous observations, we have worked to fill that gap, and we are using that information to provide some of the most important advances in cosmology in the past decade,” he said.
Astrophysicist Jean-Paul Kneib of the Swiss Federal Institute of Technology (EPFL) in Lausanne, who started eBOSS in 2012, said the goal was to produce “the most comprehensive 3D map of the Universe throughout the life of the Universe.”
For the first time, the researchers turned to “celestial objects that indicate the distribution of matter in the distant Universe, galaxies that actively form stars and quasars.”
The map shows strands of matter and voids that more precisely define the structure of the Universe since its inception, when it was only 380,000 years old.
For the part of the map related to the Universe six billion years ago, researchers looked at the oldest and reddest galaxies.
For more distant times, they concentrated on the youngest galaxies: the blue ones. To back out further, they used quasars, galaxies whose supermassive black hole is extremely bright.
The map reveals that the expansion of the Universe began to accelerate at some point and has continued to do so ever since.
The researchers said this appears to be due to the presence of dark energy, an invisible element that fits into Albert Einstein’s general theory of relativity, but whose origin is not yet understood.
Astrophysicists have known for years that the Universe is expanding, but they have not been able to accurately measure the rate of expansion.
Comparisons of the eBOSS observations with previous studies of the early universe have revealed discrepancies in the estimates of the rate of expansion.
The currently accepted rate, called the “Hubble constant,” is 10 percent slower than the value calculated from the distances between the galaxies closest to us.
© 2020 AFP
