ATLAS of the Universe: Galaxies Galore

A recent highlight for all astronomers working on Herschel data was the first ever meeting of results presented to the scientific community at the Herschel First Results Symposium, which took place in May 2010, one year after the launch of Herschel.   Professor Steve Eales from the Herschel-ATLAS was one of a few lead astronomers invited to present their results to the media and the public (you can watch the presentation online here).  Professor Eales was describing the exciting work of Herschel ATLAS which is measuring the infrared light from thousands of galaxies, spread across billions of light-years.  Describing the first Herschel ATLAS image, each galaxy appears as just a pinprick but its brightness allows astronomers to determine how quickly it is forming stars.  Roughly speaking, the brighter the galaxy the more stars it is forming.  Dr Loretta Dunne from Nottingham University said, "There are literally thousands of galaxies in this image. We've gone from detecting a couple of objects in twenty nights of data to tens of thousands of galaxies in sixteen hours! It's an incredible leap in discovery power.”

Until now, astronomers believed that galaxies have been forming stars at about the same rate for the last three billion years. Herschel shows this is not true, finding that galaxies have been changing over cosmic time much faster than previously thought.

These images show that in the past there were many more galaxies forming stars much faster than our own Galaxy.  But what triggered this frantic activity is not completely understood. But investigating the evolution of galaxies is just one of the science projects that the Herschel ATLAS will carry out. This survey will cover one eightieth of the sky, four times larger than all the other Herschel surveys combined.  “The Herschel ATLAS is able to see the infrared light from newly forming stars in our own Galaxy, and even dusty disks from which planets will form”, said Dr Mark Thompson of the University of Hertfordshire. 

Professor Asantha Cooray, of University of California Irvine, said “All this, combined with finding the hidden action in galaxies over the past 10 billion years of cosmic history, makes Herschel ATLAS a truly diverse project. Every time astronomers have observed the universe in a new waveband, they have discovered something new.  So as well as our regular science programmes, I am hoping for the unexpected.”

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