Astronomers map the hidden Universe

Astronomers from Cardiff University are completing the first survey ever for cosmic hydrogen, the primeval gas which emerged from the Big Bang to form all the stars and galaxies we can see today.

Since 1997 the astronomers, with their Australian colleagues, have been using two giant radio telescopes, the 64-metre diameter dish at Parkes in New South Wales, Australia, and the 76-metre dish at Jodrell Bank in Cheshire, England to build up an atlas of the heavens as mapped by cosmic hydrogen.

The survey is fundamental for two entirely different reasons. First of all the night sky, in cosmic terms, is quite bright so that structures dimmer than the sky will be invisible to optical telescopes – but not to the radio. Thus parts of the ’Invisible Universe’ should come to light for the first time – and they do.

Secondly, finding the gas left behind when the galaxies formed should help decode the evolution of the Universe as it expands. For instance the team finds, for the very first time, infantile galaxies still apparently commingling out of pristine gas.

So many exciting and surprising discoveries are emerging from the survey that Professor Mike Disney and his team find themselves constantly dashing around the globe to follow them up with other telescopes in Australia, New Mexico, Holland, Chile, the Canaries and South Africa, to say nothing of the Hubble Space Telescope.

“We are racing against time, against man-made radio-interference which will soon blind us to much of the cosmos for ever,” said Professor Disney.

“We feel very privileged,” he added. “We are like the early navigators glimpsing new continents for the first time. There are surprises and inevitably we only understand a fraction of what we encounter. The real challenge is to distinguish what is actually there from what we wanted to find. But none amongst us would wish to be anywhere else.”

Members of Professor Disney’s team include Hugh Lang (engineer), Dr Robert Minchin and Dr Erwin de Blok, Diege Garcia and Marco Grossi (PhD students) and Thomas Targett (undergraduate student).