ISO unveils a violent early universe
28 October 1998In astronomy, looking far into space means also looking back in time. This is what ISO has been doing during its so-called 'deep surveys':observation programmes to detect the faintest and farthest objects ever seen at infrared wavelengths.
The results reveal an early universe much more violent than expected: "We have definitively found a population of luminous starbursting galaxies, with two to three times more stars being formed than the rate inferred originally from the optical surveys," said astronomer Michael Rowan-Robinson (Imperial College, London, UK).
The last session of the international meeting "The Universe as seen by ISO", held last week in Paris and attended by about 400 astronomers, was almost entirely devoted to the deep surveys. Throughout its lifetime ISO has performed about ten of these programmes, at several infrared wavelengths. They required a strong collaborative effort from different groups and usually took many hours of observation.
In most cases the huge amount of data gathered has not been fully analyzed yet, for example the ELAIS programme, aimed at identifying for the first time thousands of new far infrared sources. Other programmes, such as the search for infrared-bright gravitational arcs, led by Leo Metcalfe (ISO Science Operation Centre, Villafranca del Castillo, Spain), have already produced amazingly beautiful results.
However, all data from the deep surveys point to the same conclusion: it is now clear that our view of the early universe has to date been hampered by the dust. ISO's unique ability to peer into these opaque regions is unveiling a young universe much more vigorous than it was thought to be, with many more stars being formed.
"There's real consensus now that the first estimates regarding star-formation rates in the early universe were definitively low. The assumptions based on optical observations were wrong due to the effect of the dust, and they will now have to be corrected," Rowan-Robinson stated.
A look to the future, especially to the infrared space telescopes that it will bring, closed the Conference. After a non-stop week of work, hundreds of astronomers remained glued to their seats hearing presentations about projects such as ESA's FIRST (Far Infrared and Submillimetre Telescope) - due to launch in 2007 - or the huge space interferometers planned for the second decade of the next millenium. They nodded in agreement when ESA's Director of Science , Roger Bonnet, said in his talk: "We need future projects to continue the wonderful work you are doing here, unveiling the infrared Universe."