‘Superclusters’ of Quasars Discovered : Astronomy: The finding by a German satellite could be more evidence against a popular theory on the evolution of the universe.
A German research satellite has discovered evidence of “superclusters” of quasars on the edge of the universe, a finding that could further complicate the lives of cosmologists who are struggling to explain how the universe evolved into its present state.
The giant communities of quasars, which are among the oldest and most luminous objects in the universe, measure 15 to 30 million light-years in diameter and are about 10 billion light-years from Earth, making them the most distant large-scale structures ever observed. A light-year is the distance light travels in a year, nearly 6 trillion miles.
If it turns out that such superclusters were common in the early universe, it could be the death knell for the “cold dark matter theory,” one of the most popular methods for explaining how the universe began with a Big Bang.
For years, scientists have maintained that the universe began with a massive explosion that sent matter in all directions. Theoretically, the matter should have been evenly distributed. Recent results show that the remnants of the Big Bang are quite homogeneous, thus supporting that theory. However, the Big Bang did not explain how some matter coalesced into giant galaxies of stars, and recent discoveries have shown that the universe is awash with large-scale structures.
The most common explanation for the huge structures is the cold dark matter theory, which holds that most of the universe is invisible and the distribution of that invisible matter caused gravitational fluctuations that created the giant structures.
“The cold dark matter theory is in trouble,” said Alan Dressler of the Carnegie Institute, because the structures that are now being discovered are so large that it is becoming increasingly difficult to explain their existence by the presence of unseen matter.
The Big Bang theory itself is still widely embraced, but some of its tenets, including cold dark matter, are being severely challenged.
Tuesday, scientists with the German X-ray satellite Rosat told the American Astronomical Society here that their instrument had found what appear to be superclusters of quasars.
Rosat has discovered hundreds of new quasars. And, said Guenther Hasinger of the Max Planck Institute for Extraterrestrial Physics, “The quasars are not distributed in a random way, but are in clusters.”
This finding “will pose a bigger problem” for cosmologists, he said, because if such clusters are common in the early universe they could not have been formed that quickly by the gravitational influence of cold dark matter. Dressler said a few superclusters would not be a problem, because some must have formed early. But if they are common, then cold dark matter is in deep trouble.
A number of other research projects are planned, including an intense study of the area found by Rosat by the Very Large Array of radio telescopes in New Mexico.
