Article Posted on : - Oct 18, 2010

PARIS (BNS): Galaxies in the early Universe grew by absorbing the cool gas surrounding them and also using it as fuel for stellar formation, a team of European astronomers has found.

While the common theory is that smaller galaxies took the shape of giant systems by colliding and merging with each other as the Universe evolved, the new theory suggests that galaxies can also grow by sucking in the cool gas around them.

A group of scientists using data provided by ESO's Very Large Telescope (VLT) has found direct evidence that young galaxies can grow by feeding on their surrounding gas. This cool stream of hydrogen and helium gas, that filled the early Universe, is also the source of new star-formation.

“The new results from the VLT are the first direct evidence that the accretion of pristine gas really happened and was enough to fuel vigorous star formation and the growth of massive galaxies in the young Universe,” the research team leader, Giovanni Cresci, said.

The team probed three distant galaxies seen about two billion years after the Universe was formed.

While the galaxies of present-day Universe have heavy materials like oxygen, nitrogen and carbon closer to their centre, the three galaxies selected by the researchers had fewer such elements at the centre, but were hosting vigorously forming stars, suggesting that the material to fuel the star formation was coming from the surrounding pristine gas that is low in heavy elements.

This was the smoking gun that provided the best evidence yet of young galaxies accreting primitive gas and using it to form new generations of stars.

The new discovery, which is expected to give a new insight into our understanding of the evolution of Universe and that of the galaxies, appears in the latest issue of the journal Nature.