New Findings Challenge Galaxy Formation Ideas

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An international team of astronomers have undertaken a survey with a new submillimeter 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. These submillimeter galaxies are associated with the early formation of some of the most massive galaxies in the present-day Universe: giant elliptical galaxies. One of these galaxies is an example of a rare class of starburst, seen just 1 billion years after the Big Bang, and may present a direct challenge to 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, when giant elliptical galaxies formed

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 submillimeter 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 submillimeter 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 submillimeter 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. Kristin Coppin of Durham University and the LESS team suggest that there could be far more submillimeter galaxies lurking at these early times than had previously been thought. “The discovery of a larger number of such active galaxies at such an early time would be at odds with current galaxy formation models,” said Coppin.

Coppin presented the team’s findings at the European Week of Astronomy and Space Science conference.

Source: RAS