23 September 2015 – UK researchers have played a key role in an international experiment, designed to find the ripples in the fabric of space-time, which has just undergone a major upgrade and is operational once more.
Laboratories in the USA operating the Advanced LIGO (aLIGO) systems have started searching for the gravitational waves that are predicted to reach the Earth when violent events occur in distant space. The upgrade should give them the enhanced sensitivity needed to pick up the very subtle signals these waves are expected to produce.
Advanced LIGO detector
The UK researchers are funded by the Science and Technology Facilities Council (STFC) and have played a vital role in developing these key aLIGO systems in the British-German part of this upgrade.
The UK team, from the Institute for Gravitational Research (IGR) at the University of Glasgow, the University of Birmingham, the Science and Technology Facilities Council (STFC) Rutherford Appleton Laboratory and collaborators from the University of Strathclyde, supplied the suspension technology which holds the aLIGO interferometer’s mirrors in place. Passing gravitational waves should cause motion of these ultra-quiet mirrors signalling the arrival of the waves. In addition researchers at Cardiff University’s School of Physics and Astronomy, together with colleagues from Birmingham and Glasgow Universities, will use a powerful supercomputer to comb through data from aLIGO’s gravitational wave detectors to find the gravitational wave signal.
The upgraded silica suspensions were developed from those used in the GEO600, an interferometric gravitational-wave detector with 600 meter long laser beam tubes, located near Hannover, Germany. Novel technology essential to the Advanced LIGO programme was pioneered on this German-British detector.
Professor Sheila Rowan, Director of the IGR, said: “I am delighted that the precision fused-silica suspensions, developed from those in the GEO600 detector and upgraded to carry 40-kg mirrors, have been successfully integrated into the Advanced LIGO detectors. This opens the way for observing to start in the near future.”
Professor Kenneth Strain, Deputy Director of the IGR at the University of Glasgow and principal investigator of the Advanced LIGO project team in the UK said: "The aLIGO project is immensely important in developing our understanding of the universe, and we’re pleased and proud to have been involved from the start following our close involvement with the original LIGO initiative.”
Gravitational waves were predicted by Albert Einstein in 1916 as a consequence of his general theory of relativity, and are emitted by violent events in the universe such as exploding stars and colliding black holes. These waves carry information not only about the objects that produce them, but also about the nature of gravity in extreme conditions that cannot be obtained by other astronomical tools.
Professor Alberto Vecchio, from the University of Birmingham's School of Physics and Astronomy, said: 'Advanced LIGO is set to open a new era in astronomy for studies of some of the Universe's most extreme environments. I am delighted that the University of Birmingham has been involved in this pioneering project since the beginning. We have successfully provided sensors for the instrument's new suspensions and highly sophisticated analysis algorithms that will be used to tease out unprecedented information about merging compact objects from Advanced LIGO data.'
Professor Andreas Freise, from the University of Birmingham's School of Physics and Astronomy, said: 'The Advanced LIGO detectors are the most sensitive gravitational wave detectors ever built. It is very exciting to see the new technologies developed over the last years now coming together to create these extremely sensitive listening devices for gravity signals from the universe.'
Professor B S Sathyaprakash, from Cardiff University’s School of Physics and Astronomy, said: “Advanced LIGO will open a new window for us to observe violent processes in the Universe, such as black holes colliding at near the speed of light. We will make use of the Cardiff University supercomputer to search through aLIGO’s detector data to identify the tell-tale signs of a gravitational wave signal. We hope to use these observations to understand the nature of space-time and matter under extreme conditions, and to test Einstein's theory of gravity when gravitational fields become super strong.”
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LIGO was designed and is operated by Caltech and MIT, with funding from the National Science Foundation (NSF). Advanced LIGO is funded by the NSF with important contributions from the UK Science and Technology Facilities Council (STFC), the Max Planck Society of Germany, and the Australian Research Council (ARC).