Researchers from the University of Melbourne and the United States detected the radiation of hydrogen from an unknown galaxy three billion light years away -- twice the cosmological distance anyone has been able to detect hydrogen before.

The detection of hydrogen at this distance will enable researchers to look back in time to a point where we can witness the evolution of the universe, see galaxies evolve and detect the rate of star formation in a much younger universe.

Dr. Martin Zwaan, a University of Melbourne postdoctoral researcher, and Peter van Dokkum and Marc Verheijen from the United States pointed the Westerbork Synthesis Radio Telescope (WSRT) in the Netherlands at the galaxy cluster Abell 2218 for 18 nights.

What they found was a new galaxy and proof that this technique could be used to detect hydrogen at these extreme distances in space.

"Until now, radiation from hydrogen has only been detected in galaxies closer than 1.5 billion light years away. Objects within this region are considered 'local' by astronomical standards," says Dr. Zwaan.

To confirm that their data was real, they double-checked it against images from the giant Keck optical telescope in Hawaii.

The research team got its data using a radio frequency of around 1200 Megahertz, a frequency outside the protected frequency bands for radio astronomy.

Normally, radiation from hydrogen is detected at 1420 megahertz -- a frequency within the protected bands. But the extraordinary distance of the galaxy found by Dr. Zwaan and his colleagues and the fact that the universe is expanding away from us at a large velocity means that the frequency at which the radiation of hydrogen is detected shifts to 1200 megahertz.

"We were getting interference from satellites and every taxi and truckie using their radio near the telescope, so we had to carefully inspect and edit every piece of our data," says Dr. Zwaan.

Stars form from hydrogen. Astrophysicists traditionally used the detection of hydrogen to study the rotation of galaxies. Detecting hydrogen also gives astrophysicists a better understanding of the rate of star formation and how much fuel for star formation there is in a galaxy.

"Now that we know we can detect radiation from hydrogen at these extreme distances we can use the new generation of radio telescopes currently being developed to peer back even further in time," says Dr. Zwaan.

"Our research looked back at only about 20 per cent of the age of the universe. New radio telescopes such as the Square Kilometre Array (SKA) that Australia is bidding to have built here will be able to look back at over 90 per cent of the age of the universe. That is more than ten billion light years -- almost to the beginning of time," he says.

Dr. Zwaan is from the Netherlands and is at the University of Melbourne doing postdoctoral research. His paper was published in the September 7 edition of Science. - By Jason Major

[Contact: Dr. Martin Zwaan, Jason Major ]

14-Sep-2001