If you thought the Hubble Deep Field galaxy photo was the most incredible thing you’ve ever seen, wait until you lay eyes on the most sensitive infrared map of the distant Universe ever taken. Over the last three years, UK astronomers have compiled data from the United Kingdom Infrared Telescope (UKIRT) in Hawaii and their results are nothing less than astounding.
Today, Dr. Sebastien Foucaud from the University of Nottingham presented his first results to the April 4 National Astronomy Meeting of the Royal Astronomical Society. These results only form part of the Ultra-Deep Survey (UDS) – an image containing over 100,000 galaxies over an area four times the size of the full Moon – and a look into the formation of the most distant galaxies yet witnessed.
The 3.8-metre (12.5-foot) UK Infrared Telescope (UKIRT) became a time machine as the world’s largest telescope dedicated solely to infrared astronomy began its Deep Sky Survey in 2005. Even now, the UDS image is but only one element of a five-part project. Due to the constraints of the speed of light, these observations allow astronomers to literally look back 10 billion years in time. The images that UKIRT produces see our Universe in its distant infancy, and the formation galaxies which date to back where we believe expansion began. The image is so large and so deep that thousands of galaxies can be studied at these early epochs for the very first time. Through the technological advance of infrared imaging, astronomers can now peer even further back in time, since light from the most distant galaxies is shifted towards redder wavelengths as it travels through the expanding Universe.
“I would compare these observations to the ice cores drilled deep into the Antarctic,” said Dr. Foucaud. “Just as they allow us to peer back in time, our ultra-deep image allows us to look back and observe galaxies evolving at different stages in cosmic history, all the way back to just 1 billion years after the Big Bang”.
One of the goals of the project is to further scientific understanding about the time frame in which rare, massive galaxies formed in the distant Universe. It is a puzzle that has simply remained unsolved. Says Dr. Foucaud: “We see galaxies 10 times the mass of the Milky Way already in place at very early epochs. Now, for the first time, we are sampling a large enough volume of the distant Universe to be able to see them in sufficient numbers and really pin down when they were formed.”
The UKIDSS Ultra-Deep Survey will, in time, give us a complete census of galaxy formation in the infrared. So far over one hundred thousand galaxies have been detected and the final image will be 100 times larger than any equivalent survey to date. Determining precise distances to faint galaxies is very difficult, requiring long hours of spectroscopy. For the faintest objects in the UDS survey this is often impossible. Instead, by using optical and infrared colors, astronomers are very effectively able separate distant galaxies from those which are nearby, and further separate them into those which are forming stars and those which are not. UKIDSS aims to discover the nearest object to the Sun (outside the solar system) as well as some of the farthest known objects in the Universe.
Does the Ultra-Deep Sky Survey images shed light on the great cosmological mystery? Only time – and distance – will tell. Professor Andy Lawrence, Principle Investigator of UKIDSS from the University of Edinburgh, said “As we keep taking images over the next few years, we will see ever more distant galaxies.”