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The Feeding Habits of Teenage Galaxies

New observations made with ESO's Very Large Telescope are making a major contribution to understanding the growth of adolescent galaxies. In the biggest survey of its kind astronomers have found that galaxies changed their eating habits during their teenage years - the period from about 3 to 5 billion years after the Big Bang. At the start of this phase smooth gas flow was the preferred snack, but later, galaxies mostly grew by cannibalising other smaller galaxies.
Astronomers have known for some time that the earliest galaxies were much smaller than the impressive spiral and elliptical galaxies that now fill the Universe. Over the lifetime of the cosmos galaxies have put on a great deal of weight but their food, and eating habits, are still mysterious. A new survey of carefully selected galaxies has focussed on their teenage years - roughly the period from about 3 to 5 billion years after the Big Bang.

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New observations from ESO's Very Large Telescope have, for the first time, provided direct evidence that young galaxies can grow by sucking in the cool gas around them and using it as fuel for the formation of many new stars. In the first few billion years after the Big Bang the mass of a typical galaxy increased dramatically and understanding why this happened is one of the hottest problems in modern astrophysics. The results appear in the 14 October issue of the journal Nature.
The first galaxies formed well before the Universe was one billion years old and were much smaller than the giant systems - including the Milky Way - that we see today. So somehow the average galaxy size has increased as the Universe has evolved. Galaxies often collide and then merge to form larger systems and this process is certainly an important growth mechanism. However, an additional, gentler way has been proposed.

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Intense heat killed the Universe's would-be galaxies
Millions of would-be galaxies failed to develop after being exposed to intense heat from the first stars and black holes formed in the early Universe, according to new research.
Our Milky Way galaxy only survived because it was already immersed in a large clump of dark matter which trapped gases inside it, scientists led by Durham University"s Institute for Computational Cosmology (ICC) found.
The research, to be presented at an international conference today (Wednesday, July 1), also forms a core part of a new ICC movie charting the evolution of the Milky Way to be shown at the Royal Society.
The researchers said that the early Milky Way, which had begun forming stars, held on to the raw gaseous material from which further stars would be made. This material would otherwise have been evaporated by the high temperatures generated by the "ignition" of the Universe about half-a-billion years after the Big Bang.

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Young Spiral Galaxies
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Newfound spiral galaxies oddly young
Astronomers have discovered an unexpected cache of spiral galaxies that appear to have formed recently, long after the period early in the history of the universe that most galaxies were thought to have been created.

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A team led by an Indiana University astronomer has found a sample of massive galaxies with properties that suggest they may have formed relatively recently. This would run counter to the widely-held belief that massive, luminous galaxies (like our own Milky Way Galaxy) began their formation and evolution shortly after the Big Bang, some 13 billion years ago. Further research into the nature of these objects could open new windows into the study of the origin and early evolution of galaxies.

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Slurping up cold streams of star fuel, some of the Universe's first galaxies got fat quickly, new observations suggest. The findings could overturn existing models for the formation and evolution of galaxies that predict their slow and steady growth through mergers.
Researchers using the Subaru telescope in Hawaii have identified five distant galaxy clusters that formed five billion years after the Big Bang. They calculated the mass of the biggest galaxy in each of the clusters and found, to their surprise, that the ancient galaxies were roughly as big as the biggest galaxies in equivalent clusters in today's Universe. The ancient galaxies should have been much smaller, at only a fifth of today's mass, based on galaxy-formation models that predict slow, protracted growth.

"That was the reason for the surprise - that it disagrees so radically with what the predictions told us we should be seeing" - Chris Collins of Liverpool John Moores University in Birkenhead, UK. Collins and his colleagues publish the work today in Nature.

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Scientists have used a supercomputer to simulate what the Universe was like as the first galaxies were forming.
The model maps how matter is thought to have been distributed a few hundred million years after the Big Bang.

_45472532_cosmicdawnz=8.5large.jpg

The work should help astronomers hunt down ancient galaxies using the latest telescope technologies - they will know what to look for.
The simulation has been produced by scientists at Durham University's Institute of Computational Cosmology.

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A Pool of Distant Galaxies Credit: ESO/ Mario Nonino, Piero Rosati and the ESO GOODS Team.

The Chandra Deep Field South, observed in the U-, B-, and R-bands with ESO's VIMOS and WFI instruments. The U-band VIMOS observations were made over a period of 40 hours and constitute the deepest image ever taken from the ground in the U-band. The image covers a region of 14.1 x 21.6 arcmin on the sky and shows galaxies that are 1 billion times fainter than can be seen by the unaided eye. The VIMOS R-band image was assembled by the ESO/GOODS team from archival data, while the WFI B-band image was produced by the GABODS team. 

Source ESO



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A bit of serendipity has given astronomers a surprise view of a never-before-observed event in the birth of a galaxy.
University of Florida and University of California-Santa Cruz astronomers are the first to discover the onset of a huge flow of gas from a quasar, or the super-bright core of an extremely remote young galaxy still being formed. The gas was expelled from the quasar and its enormous black hole sometime in the space of four years around 10 billion years ago an extremely brief and ancient blip noticed only by a sharp-eyed undergraduate and the unlikely convergence of two separate observational efforts.

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A Cosmic Eye has given scientists a unique insight into galaxy formation in the very early Universe.
Using gravity from a foreground galaxy as a zoom lens the team was able to see a young star-forming galaxy in the distant Universe as it appeared only two billion years after the Big Bang.
Scientists at the California Institute of Technology (Caltech), USA, and Durham University and Cardiff University, UK, are behind the research published today (Thursday, October 9) in the prestigious scientific journal Nature.

 
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