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Durham University News

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High-tech instrument to answer Universe’s key questions

(9 October 2012)

IFU Assembly

A high-tech instrument led by Durham University could soon answer some of the key questions about the beginnings of the Universe and the formation of its first stars and galaxies.

The KMOS (K-Band Multi Object Spectrometer) has been partly manufactured by the Centre for Advanced Instrumentation at the Netpark Research Institute, near Sedgefield, County Durham.

After final assembly and testing at the UK Astronomy Technology Centre in Edinburgh, KMOS – which has 24 robotic arms to allow simultaneous observations of multiple objects - has been provisionally accepted by the European Southern Observatory (ESO).

It has travelled to South America where it will be fitted to one of the four telescopes which make up the European Southern Observatory’s Very Large Telescope (ESO-VLT) at Paranal, in Chile, providing astronomers with a far quicker solution to uncover details about galaxies and their properties.

Durham University hosts the project Principal Investigator Professor Ray Sharples, of the Department of Physics, who is also the Director of the Centre for Advanced Instrumentation.

Professor Sharples said: “One of the unique features of KMOS is the system of diamond-machined image slicers, produced by Durham Precision Optics, which consists of over a thousand gold-coated optical surfaces each manufactured with a precision of a few billionths of a metre.

“The optical system is one of the most complex ever assembled and builds upon our previous development of an image slicer for the James Webb Space Telescope.

“The University is proud to be participating in this cutting edge technology international project together with our UK and German partners, which will be the first UK-led common user instrument for the ESO-VLT.

“The instrument will provide a uniquely powerful tool for studying the formation and evolution of galaxies like our own Milky Way and is eagerly anticipated by observational cosmologists working both in Durham and Europe.”

What makes KMOS unique is its ability to image many galaxies simultaneously, but via the use of image slicers still see the individual properties of each single galaxy. Until now, each galaxy has had to be identified individually to obtain that information, a process that takes years. KMOS will be able to see the same amount of detail in just two months.

Each of its 24 cryogenic robotic arms is moved into position to pinpoint, with extreme accuracy, the light coming from distant galaxies. This is then fed to the image slicer system for detailed spectral analysis.

Dr Michele Cirasuolo is the lead instrument scientist for KMOS at UK ATC. He said: “KMOS represents a pivotal step in our quest to scrutinise the distant Universe. The ability to observe in the near-infrared 24 galaxies simultaneously is an enormous leap forward compared to any other current instrument. KMOS will allow a much faster survey speed. Most of the observations done by similar near-infrared spectrographs over the last 10 years could be done in just two months with KMOS.”

This novel capability means astronomers will be able to make a detailed study of the mass assembly and star formation in the very earliest galaxies addressing fundamental questions about when these first formed and how they evolve. This ability to observe multiple galaxies at once enables scientists to build up large statistical samples of galaxies at different cosmic epochs necessary to unveil the physical mechanisms that shape their formation and evolution.

The specialised mechanisms inside KMOS have been designed to work in cryogenic conditions below minus two hundred degrees centigrade, which has been a major challenge, but which is necessary to observe distant galaxies at near-infrared wavelengths. This is because, unless cooled, the thermal emission from the instrument itself will swamp the faint signal from the astronomical sources.

Minister for Universities and Science David Willetts said: "It’s excellent to see the UK playing a leading role in the development of such a sophisticated piece of technology and overcoming some very complex engineering challenges on the way. This instrument will now take its place on a world leading telescope to help improve our knowledge and understanding of the universe around us."

The instrument is a collaboration of six institutions in Germany and the UK, including STFC’s UK Astronomy Technology Centre (UK ATC), Durham University, Oxford University and RAL Space at STFC’s Rutherford Appleton Laboratory. The team of internationally respected scientists and engineers at UK ATC played a major role in the KMOS project, being responsible, amongst others, for the construction of the cryostat, the 24 robotic pick-off arms, the cable co-rotator and the final assembly and test of the complete instrument.

RAL Space applied their cryogenic lens mounting technology in the three camera barrels they provided for spectrographs in KMOS. Durham University has the PI of the entire project and produced the complex system of more than 1,000 mirrors in the integral field unit. Oxford University provided the design and assembly of the three spectrographs in KMOS.

Each incredibly powerful unit telescope on the VLT contains a mirror eight metres in diameter. It is onto the VLT Unit 1 telescope, Antu that the new KMOS equipment will be fitted.

For more information about the Centre for Advanced Instrumentation go to: http://www.dur.ac.uk/cfai

For more information about Durham Precision Optics visit: http://www.durhamprecisionoptics.co.uk

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