Australia expands its role in the hunt for gravitational waves

Physicists from around Australia today met at the Australian International Gravitational Research Centre (AIGCRC), in Gingin, WA, to launch a nationwide project that expands our participation in the hunt for elusive gravitational waves.

Gravitational waves are ripples in the curvature of space-time, thought to mark the beginning of time at the big bang and the end of time as black holes are born. They are generated by extreme cosmic events such as colliding stars and supernova explosions. Theory predicts that they carry vast amounts of energy at the speed of light. But while their power can exceed the power of all the stars in the universe, their effects are miniscule and difficult to detect.

The AIGRC’s director, Winthrop Professor David Blair of The University of Western Australia (UWA), said 1000 physicists around the world are currently involved in the search for gravitational waves, which is focused on the commissioning of three enormous super-sensitive detectors that will start operating within the next few years in the USA and Europe, with another under construction in Japan. According to Professor Peter Veitch, Chair of the Australian Consortium for Gravitational Astronomy, these detectors provide scientists with “firm predictions: both the strength and the number of signals”.

“No longer are we hoping for rare and unknown events,” he said. “We will be monitoring a significant volume of the universe and for the first time we can be confident that we will ‘listen’ to the coalescence of binary neutron star systems and the formation of black holes. Once these detectors reach full sensitivity, we should hear signals almost once a week.”

Australia has been engaged in the international search for gravitational waves for more than 20 years. The new project has two components: one involving experiments at the AIGCRC, and one involving signal detection using the iVEC supercomputer being installed at WA’s Pawsey Centre. Valued at over $2 million, the project has received funding from the Australian Research Council, UWA, Australian National University (ANU), the Universities of Adelaide and Melbourne, CSIRO, iVEC and AARNet, and the Albert Einstein Institute in Hannover, Germany.

The experimental team will be installing high-purity fused silica mirrors developed by CSIRO, along with state-of-of-the-art optical sensors developed in Adelaide and control technology developed at ANU. All this equipment will be used to develop control technology needed by the big detectors in the USA and Europe to prevent possible instabilities, and ensure that the detectors can operate for long periods of time as they listen to the sounds of the universe.

The new detectors are the Advanced LIGO (laser interferometer gravitational observatory) detectors at Hanford and Livingston in the USA, and the Advanced Virgo detector in Cascina, Italy. Data from the detectors will be used in conjunction with optical telescopes that will search the sky for visible signs of the catastrophic events signalled by the gravitational waves. Australia is contributing two telescopes to the search: the Zadko telescope at Gingin and the Skymapper telescope at Coonabarrabran in NSW.

The data from the detectors will be distributed to data analysis teams in many countries. The Australian data analysis team has developed techniques for digging signals out of the unavoidable noise in the detectors, plus techniques that use graphics processing units for detecting signals the instant they occur (instead of traditional techniques which can take minutes or hours to identify signals). This fast detection method is especially important if optical telescopes are going to be able to locate distant explosions the moment they occur, such as the coalescence of pairs of neutron stars to form a black hole.

Pawsey Centre supercomputers will be equipped with ‘search pipelines’ developed at ANU, Melbourne and UWA. These are massive computer codes designed to separate signals from the noise. Each pipeline is optimised for a specific type of signal, such as the chirps expected as neutron stars spiral together and black holes form. Using these codes, Australian students will be able to play a major role in the first discovery of gravitational waves.

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