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The birth of galaxies in the Universe: “galaxy hunters” meet in Heidelberg

Two hundred astronomers from across the world gathered last week in Heidelberg to brainstorm about one of the most important puzzles in astrophysics: how, and when, did galaxies like our own Milky Way form in the Universe?

Using the most powerful telescopes in the world and out of this world — in space, astronomers hunt for the progenitors of today's giant galaxies which formed during the first two billion years of our 13.7 billion year-old Universe.  Astronomers believe this is the epoch during which galaxies build up from a very small number of stars. As time went on, more and more stars and gas were pulled together by the force of gravity to form the large galaxies we see today.

"The first 900 million years after the Big Bang, when the Universe was in its infancy, is the frontier for exploration, and is where we are searching for the first signs of galaxies in formation", said Prof. Garth Illingworth from the University of California at Santa Cruz, member of an international team of astronomers led by Dr. Richard Bouwens. The team conducted an extensive search for galaxies in the early Universe and discovered more than 500 baby galaxies from the time when the Universe was just seven percent of its present age. "We are now hunting further back in cosmic time and have 10 new good candidates from the time when the Universe was only 700 million years old", Prof. Illingworth added.

Another crucial question addressed at the conference was: how do galaxies evolve over time? Astronomers believe that a key piece of the puzzle is the so-called "merging process": galaxies grow larger by devouring smaller galaxies. Merging is the reason why some galaxies have very peculiar shapes. Although they appear like one single odd-looking object they are in fact the aftermath of the merging between two parent galaxies. Mergers trigger the formation of new stars, make galaxies larger and transform their shapes.

Amongst the big list of challenges astronomers face are how giant black holes — the cosmic monsters that swallow everything that ventures near them — grow at the centre of galaxies and finding out the nature of the Universe's hidden constituents — dark matter and dark energy — which play a significant role in the formation of galaxies.

The latest findings in the field of galaxy formation and evolution presented by experts from around the world in a conference titled "Galaxy growth in a Dark Universe" held in Heidelberg's Kongresshaus last week portend an exciting future of "galaxy hunting".
Ana Lopes

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Dr. Michael Schwarz
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University of Heidelberg
phone: 06221/542310, fax: 542317

Ana Margarida Lopes
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