[1]An international team of astronomers has produced the first map of the universe as it was 11 billion years ago, filling a gap between the Big Bang and the rapid expansion that followed.
The study, published in the journal Astronomy & Astrophysics, shows the universe went through a phase roughly three billion years after the Big Bang when expansion actually started to slow, before the force of so-called “dark energy” kicked in and sent galaxies accelerating away from each other.
The map, the work of 63 scientists from nine countries, was compiled using a novel technique for studying the intense light from 50,000 distant qua-sars as it passes through clouds of hydrogen in space on its way to earth.
They produce a picture of the ancient universe in same way thousands of flashlight beams would light up a bank of fog.
“The quasars are back-lights,” said Mat Pieri at the University of Ports-mouth in Britain, one of the authors of the study. He added that the way the gas in front of them absorbs some of the light allows astronomers to get a detailed picture of these distant clouds of gas known as the intergalactic medium.
The study is the first fruit from a five-year project started in 2009. The team, from the third Sloan Digital Sky Survey, expect to expand the survey with light from about 160,000 quasars by the end of the project. Much is known about the immediate aftermath of the Big Bang from studies of its afterglow in the cosmic background radiation, and its accelerating expansion over several billion years can be seen with a look at the way distant galaxies are moving.
“Only now are we finally seeing its adolescence, just before it underwent a growth spurt,” said Pieri.
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