An international team of astronomers, undertaking a survey with a new submillimetre camera, have discovered more than a hundred dusty galaxies in the early Universe, each of which is in the throes of an intense burst of star formation. One of these galaxies is an example of a rare class of starburst, seen just one billion years after the Big Bang.
In her presentation on Wednesday 22nd April at the European Week of Astronomy and Space Science conference, team leader Dr. Kristen Coppin of Durham University will discuss the new results and how they may present a direct challenge to our current ideas of how galaxies formed.
The team (known as the LESS collaboration) used the new Large Apex Bolometer Camera (LABOCA) camera on the Atacama Pathfinder Experiment (APEX) telescope sited in the Atacama Desert in Chile to make a map of the distant galaxies in a region of the sky called the Extended Chandra Deep Field South. These galaxies are so far away that we see them as they appeared billions of years ago. LABOCA is sensitive to light at wavelengths just below 1mm (submillimetre radiation), and is able to find very dusty and very luminous galaxies at very early times in the history of the Universe. These submillimetre galaxies represent massive bursts of star formation associated with the early formation of some of the most massive galaxies in the present-day Universe: giant elliptical galaxies.
For many years it has been thought that these giant elliptical galaxies formed most of their stars at very early times in the Universe, within the first billion years after the Big Bang. However, very few examples of these very distant and very bright dusty sources have been found in submillimetre surveys, until the LESS collaboration completed their survey of a Full Moon-sized patch of sky in the southern hemisphere constellation of Fornax. Their survey is the largest and deepest of its kind in submillimetre radiation and reveals over a hundred galaxies that are forming stars at a prodigious rate.
Working with their new map, the team identified one of the submillimetre sources as being associated with a star forming galaxy which is seen just 1 billion years after the Big Bang. This remarkable galaxy shows the signatures of both intense star formation and obscured black hole growth when the Universe was only 10 percent of its current age. Dr. Coppin and the LESS team suggest that there could be far more submillimetre galaxies lurking at these early times than had previously been thought. Dr Coppin comments, “The discovery of a larger number of such active galaxies at such an early time would be at odds with current galaxy formation models”.
The team's results will appear in a forthcoming edition of Monthly Notices of the Royal Astronomical Society.
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