Miércoles 5 de Junio de 2002, Ip nº 16

Dwarf galaxy swarms boost dark matter theory
Por Richard Stenger

(CNN) --Scientists have discovered evidence that hordes of dark, miniature galaxies surround ordinary galaxies, lending credence to the theory that the universe is comprised mostly of cold, dark matter.

The astronomers, who describe their work in an upcoming issue of the Astrophysical Journal, based their finding on an in-depth study of light from distant galaxies.

The team took advantage of a phenomenon known as gravitational lensing, whereby galaxies closer to our cosmic neighborhood distort the light of galaxies farther away, much like a glass lens as it bends light.

To account for light variations, the researchers concluded that hundreds of invisible dwarf galaxies must ring the background galaxies.

An increasingly popular cosmological model holds that the universe contains large amounts of hidden dark matter because normal matter could not account for the mass needed to hold galaxies together.

The theory lost momentum when a search for dark dwarf galaxies around galaxies like our own Milky Way proved fruitless, but the latest find could give it a boost.

"The lack of observed satellite galaxies around large galaxies has been major point in the prosecution of the case against cold dark matter," said one of the researchers, Neal Dalal of the University of California, San Diego. "Our research can be regarded as a major vindication of the model."

Dalal conducted his study, partly funded by NASA and the U.S. Energy Department, with Christopher Kochanek of the Harvard Smithsonian Center for Astrophysics.

  22/05/2002. CNN.