Ghost Galaxies May Hold Dark Matter
A U S T I N, Texas, Dec. 6 -- Astronomers searching for mysterious missing matter in the universe are focusing on a new theory about “ghost galaxies” that contain few stars but are surrounded by dense halos of invisible dark matter.
An analysis of 43 galaxies shows that small, ghostly galaxies that appear to be little more than “fuzz balls” in powerful telescope images actually contain high densities of dark matter, with only a scattering of visible stars, John Kormendy of the University of Hawaii said today.
Speaking at the national meeting of the American Astronomical Society, Kormendy said there may be more of the small, dense galaxies than the bright, giant galaxies. They could, thus, contain “a significant portion” of the universe’s dark matter.
“There may be a large population of dark galaxies that contain too few stars to be discovered,” Kormendy said. “They may outnumber all of the luminous galaxies combined.”
Stars Within Galaxies Not Enough
The presence of invisible matter was determined years ago by astronomers who measured the motion of stars within galaxies. They determined that stars and clouds that shine and can be seen from Earth did not contain enough mass to hold the galaxies together.
Thus, there had to be other matter to provide the gravitational force that keeps the galaxies from flying apart.
In fact, some astronomers calculated that 90 percent of the matter in the universe cannot be seen and thus is “missing.”
Since this matter is invisible, it must be dark and cold, the astronomers reasoned. Thus, it is called “cold, dark matter.”
Holds Secrets About Our Destiny
Since then, astronomers have been scrambling to try to find and identify this missing matter because it has profound implications about the motion and ultimate destiny of the universe.
“We’re still groping,” said Vera Rubin, a Carnegie Institution of Washington astronomer and one of the original theorists about cold, dark matter. “It is as if we are in a black room working on a black puzzle.”
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