STUDY FINDINGS DEEPEN MYSTERY OF DARK MATTER IN SPACE
COLUMBUS, Ohio -- The mystery surrounding the contents of the universe's dark matter remains unsolved, according to findings by an astronomer at Ohio State University.
Andrew Gould, an assistant professor of astronomy, has proved false the widely held theory that dark matter -- which may make up about 90 percent of the universe's mass -- is comprised primarily of tiny red dwarf stars.
Gould and John Bahcall, with the Institute for Advanced Study in Princeton, N.J., led a team of scientists who used images obtained from the Hubble Space Telescope to reach their conclusions. Their research was published in a recent issue of Astrophysical Journal .
"If you asked most astronomers in the last 20 to 40 years what dark matter was made of, they'd say red dwarf stars," Gould said.
Scientists thought red dwarf stars might account for most of dark matter. But Gould's team found the stars accounted for no more than 6 percent of dark matter. While the revelation is good news to astronomers who are searching for the missing ingredient
in the matter, it also creates new questions for scientists to ponder.
"We don't know the shape of the dark matter -- whether it's flat or spherical -- and we don't know what it's made of," Gould said. "The questions of the dark matter are interconnected with other questions about the universe."
Discovering the contents of dark matter would give scientists an idea of the age of the universe and whether or not it will eventually collapse in a "big crush," Gould said.
Gould developed a software program designed to translate information from the Hubble Space Telescope images into data needed to count the red dwarf stars.
"These stars are so faint on many of these images that you can't trust the naked eye and you have to write a program that will go over the images and make sure that there aren't any stars that you missed," he said.
The results now point astronomers in different directions to continue the search for what makes up dark matter. One answer, Gould said, could be even smaller stars called brown dwarfs and other lumps of matter generically called MACHOs (Massive Compact Halo Objects). Another possibility is WIMPs (Weakly Interacting Massive Particles). All of these would be too dim to be detected by the Hubble telescope.
Experiments designed to detect MACHOs, currently being conducted in Australia and Chile, are recording events at a rapid rate. Gould is designing methods to determine whether these events are due to the MACHOs or to stars that are already accounted for.
Gould said that although the Hubble telescope images don't solve the mystery of dark matter, the findings shouldn't be perceived negatively.
"I think it's an important step in clarifying the question of the dark matter."
Other members of the research team were Chris Flynn and Sofia Kirhakos, both with the Institute for Advanced Study.
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Contact: Andrew Gould, (614) 292-1892
Written by Kelli Whitlock, (614) 292-9475