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Unveiling the Universe

05 July 2010

Image credit: ESA / LFI and HFI ConsortiaImage credit: ESA / LFI and HFI Consortia

University astronomers have helped reveal unique images of the entire sky which could help provide new insights into the way stars and galaxies form and reveal how the Universe itself came to life after the Big Bang

The Planck space observatory – the European Space Agency’s mission to study the early Universe – has beamed back its first all-sky image.

University astronomers have been involved in the design and construction of the satellite. Members of the University’s School of Physics and Astronomy are also working alongside colleagues from around the world to operate the satellite and analyse the data.

Professor Peter Ade, School of Physics and Astronomy, who led the University’s involvement in the design, construction and operation of the High Frequency Instrument said: "It is a fantastic result for this unique satellite, and demonstrates once again that you can only do pioneering science by using advanced and therefore high-risk technologies.

"At last we can see the realisation of the full potential of Planck, showing in exquisite detail our own Milky Way galaxy superimposed on the relic fireball background."

From the closest portions of the Milky Way to the furthest reaches of space and time, the new all-sky image offers an extraordinary treasure chest of new data for astronomers.

The main disc of our Galaxy runs across the centre of the image. Immediately striking are the streamers of cold dust reaching above and below the Milky Way. This galactic web is where new stars are being formed, and Planck has found many locations where individual stars are edging toward birth or just beginning their cycle of development.

Less spectacular but perhaps more intriguing is the mottled backdrop at the top and bottom. This is the cosmic microwave background (CMB) radiation. It is the oldest light in the Universe, the remains of the fireball out of which our Universe sprang into existence 13.7 billion years ago.

While the Milky Way shows us what our local neighbourhood looks like now, those microwaves show us what the Universe looked like close to its time of creation, before there were stars or galaxies. The CMB radiation was released as the first atoms were forming, about 400,000 years after the Big Bang, and is at the heart of Planck’s mission to decode what happened in the primordial Universe.

The microwave pattern is the cosmic blueprint from which today’s clusters of galaxies were built. The different colours represent minute differences in the temperature and density of matter across the sky. Through the action of gravity, these small irregularities evolved into denser regions that became the galaxies of today.

The CMB covers the entire sky but most of it is hidden in this image by the Milky Way’s emission, which must be digitally removed from the final data in order to see the microwave background in its entirety. Planck looks at the sky in nine different bands, or colours, of microwave light, which have wavelengths thousands of times that of optical light. These nine different bands, ranging from frequencies of 30 to 850 GHz, are crucial for understanding which parts of the Planck data are from the early Universe, and which are from our own Galaxy.

Dr Chris North, School of Physics and Astronomy, said "It’s wonderful to be able to share the amazing results from Planck. It has already taught us much about our own galaxy, and the work of further understanding the CMB is well underway.

"The final results should be staggering."

When this work is completed, Planck will show the most precise picture of the cosmic microwave background ever obtained. The big question will be whether the data will reveal the cosmic signature of the primordial period called inflation.

This era is postulated to have taken place just after the Big Bang and resulted in the Universe expanding enormously in size over an extremely short period. It is a cornerstone of the standard cosmological model, but results from sensitive experiments such as Planck are required to increase our understanding.

The image shown here is constructed from data taken from the first ten months of Planck’s main mission, with observations beginning in August 2009. Planck continues to map the Universe, and by the end of its mission in 2012 it will have imaged the whole sky four times.

The first full data release of the CMB is planned for 2012.

Before then, a catalogue containing individual objects, both regions in our Galaxy and entire distant galaxies, will be released in January 2011.

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