Izgleda da smo jos manji nego sto sam mislio da jesmo - kako li je tek virusima...
Far, far away and - bingo - another 14 galaxies
Chee Chee Leung
September 18, 2007
AN AUSTRALIAN astronomer is part of an international team that has discovered 14 galaxies halfway across the universe, opening up a new era of galaxy hunting.
The galaxies, which are about 7 billion light years from Earth
, have been difficult to detect, because they lie in front of bright, distant objects known as quasars.
The glare of the quasars hides the dim light from the galaxies, but a powerful infrared instrument in Chile helped the scientists uncover the galaxies.
"It effectively allows us to see through the glare of the quasar," said the researcher Dr Michael Murphy, of Swinburne University. "By chopping up the light into many finely dissected colours, we can essentially get rid of the quasar altogether, and see the galaxy coming through."
The research team, headed by Germany's Max Planck Institute for Extraterrestrial Physics, began its search by using quasars as "cosmic beacons" to reveal the presence of a galaxy.
Dr Murphy trawled through huge catalogues of quasars to find those with "dips" in their colour spectrum. This shows a galaxy is in front of the quasar, absorbing some of its light before it reaches the Earth. By studying the patches of sky around 20 of these quasars - using the European Southern Observatory's Very Large Telescope - the researchers detected the 14 galaxies, a success rate of 70 per cent.
There are estimated to be hundreds of billions of galaxies, but only about a dozen that sit in front of quasars have been detected at such a distance from Earth.
Light from these newly found galaxies comes from the time the universe was about 6 billion years old, less than half its current age. By studying the light, the researchers have determined they are "starburst galaxies" that are forming lots of new stars - the equivalent of 20 suns a year.
Dr Murphy, who began working on the project while a research fellow at the University of Cambridge, described the results as a "great leap forward" in the study of distant galaxies. The findings have been accepted for publication in The Astrophysical Journal.