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Stephen Fairhurst

Dr Stephen Fairhurst

Dr Stephen Fairhurst

Research Fellow

Interests and expertise (Subject groups)

Grants awarded

Gravitational waves from coalescing binaries: detection and astrophysics

Scheme: University Research Fellowship

Organisation: Cardiff University

Dates: Oct 2011-Sep 2014

Value: £299,768.94

Summary: The observation of gravitational waves will open up a new window on the universe. To date, virtually everything we have learned about the universe around us is based on observing light emitted by stars when it reaches the earth. Telescopes observing visible light, radio waves or X-ray have revealed dramatically different features of the universe. Looking at the sky through a gravitational wave window will reveal an entirely different view. I am a member of a worldwide collaboration of scientists is attempting to detect gravitational waves. A network of detectors has been built around the world, with instruments in Germany, Italy, US, Japan. My work focuses on searching for the telltale signal of two merging black holes or neutron stars (stars that have roughly the same mass as the sun but are only 20km across). Their observation will shed new light on the nature of these exotic objects and the astrophysical processes that lead to their formation. We are searching for a gravitational wave signal that would last a matter of seconds in a year’s worth of data taken by these detectors. Over the past decade, I have led the development of a sophisticated analysis capable of sifting through the vast amount of data and separating potential gravitational wave signals from the background of detector noise. The analysis we have developed uses advanced signal processing techniques to distinguish potential signals from the background noise, and requires a supercomputing cluster to run. The advanced mathematical, computational and statistical methods we use are increasingly applicable in an era where the internet enables the collection and exchange of ever larger amounts of data.

Gravitational waves from coalescing binaries: Detection and astrophysics

Scheme: University Research Fellowship

Organisation: Cardiff University

Dates: Jan 2007-Sep 2011

Value: £367,878.13

Summary: Gravitational waves, ripples in the fabric of space-time, were predicted by Albert Einstein shortly after his development of general relativity. Gravitational waves are formed by accelerating masses, and are typically produced in regions of the universe with strong gravitational fields. Thus, detection of gravitational waves would allow us to probe regions of strong gravity, such as black holes, cores of supernovae and gamma ray burst engines, which may not be visible to optical telescopes. No direct observation of gravitational waves has yet been made although, in 1993, Hulse and Taylor were awarded the Nobel Prize for their indirect observation of gravitational waves. They observed a binary star system which is slowly spiraling together, as it loses energy through gravitational radiation, at precisely the rate predicted by general relativity. A global network of gravitational wave detectors have been constructed in an attempt to directly detect gravitational waves. I lead the search for gravitational waves from the merger of black holes and/or neutron stars. Analysis of the most recent data from these detectors revealed evidence of the elusive signal from a neutron star spiraling into a black hole. Shortly after the collaboration approved a scientific paper reporting the ground-breaking "discovery",it was revealed that the signal was a "blind injection" --- a fake signal secretly added to the data to test the detector and analysis. While we were disappointed that the discovery was not real (we knew that it could be a blind injection), the success of the analysis was a compelling demonstration of the collaboration's readiness to detect gravitational waves. We are now looking forward to observations with the advanced detectors which are expected to contain many real signals from the distant reaches of the universe.

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