From its first day of operation in July 2019, the Gravitational Wave Data Centre (GWDC) has been the premier Australian facility for the burgeoning field of gravitational wave science. With data streaming in from observatories around the world, the Centre continues to provide support for Australian researchers – allowing them to take centre stage in the ongoing hunt for new gravitational wave events.
Based at Swinburne University of Technology, the GWDC is the first internationally-recognised gravitational wave data centre in Australia. Created to provide infrastructure, training and support to gravitational wave researchers across the country, the GWDC enables Australian researchers to lead the discovery of events from the latest data on an international scale and to maximise the scientific impact of their discoveries. This has primarily been achieved via GWDC’s support of existing pipelines, originally created to instantly process and analyse data from gravitational wave observatories located in the United States and Europe. Currently Australia’s only real-time gravitational wave detection pipeline, the Summed Parallel Infinite Impulse Response (SPIIR) pipeline has now been further developed by a collaboration between the University of Western Australia and the GWDC. Using Swinburne’s OzSTAR supercomputer extensively, researchers (including those from the ARC Centre of Excellence for Gravitational Wave Discovery – OzGrav) have been able to make several remarkable discoveries, including the first detected merger of a neutron star and black hole.
In July 2021, the Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo collaborations presented the first gravitational wave observations of a neutron star merging with a black hole. Gravitational wave researchers were able to identify the progenitor systems of this merger by using two software programs run on the OzSTAR supercomputer based at Swinburne University of Techonology. The Bilby software and its parallel implementation, pBilby, were used by LIGO and Virgo to determine the parameters of the two merging systems. Once the mass of each system had been determined, it became clear to researchers that they had discovered a new class of sources for the gravitational wave events. The GWDC contributed to the software development and optimisation of both Bilby and pBilby. In the process, the GWDC helped to uncover further properties of the NSBH systems, including the spins of the progenitor black holes and the distance to the mergers – information that helped uncover the origin of these enigmatic events. The computing capacity of OzSTAR, including both the latest nodes and the repurposed sstar nodes, was also crucial to this work. See the published paper here, in The Astrophysical Journal Letters.
Along with its work on the NSBH merger, the GWDC has also been overseeing the creation of an online portal for all pulsar data collected from the MeerKAT interferometer. MeerKAT is an SKA precursor instrument – located in South Africa – that will ultimately contribute 33% of the radio dishes required for the SKA-mid telescope. The MeerTime collaboration is currently using this portal for radio pulsar science – in particular, to facilitate the detection of gravitational waves generated by supermassive black holes lurking in the cosmos. Recently, the portal was used to conduct a census of millisecond pulsars, with 189 candidates monitored and 80 selected to form the MeerKAT pulsar timing array. MeerKAT is set to surpass NANOGrav, Parkes and the European pulsar timing array for gravitational wave sensitivity by 2025. This means MeerKAT will soon be the most dominant contributor to the International Pulsar Timing Array, thanks to contributions from the GWDC.
The OzSTAR supercomputer was also on hand to perform a deep exploration for continuous GWs in existing, publicly accessible LIGO data. With the superior sensitivity available from OzSTAR’s graphics processing units, researchers were able to hear more than ever before in a narrow, optimally chosen parameter space. While there were no gravitational waves to be heard this time, it was an encouraging exercise due to the excellent sensitivity achieved by the OzSTAR supercomputer. See the popular science article published online for more on this search.
In December 2020, the GWDC received a $1M grant from the Australian Government, via the NCRIS program, allowing it to extend operations into 2022. This funding boost has enabled Australian astronomers to continue receiving vital data from the LIGO and Virgo detectors as well as pulsar timing data from the Square Kilometre Array (SKA) and precursor facilities. These facilities currently capture gravitational waves from the collisions of stellar-mass black holes and neutron stars and hope to capture the final death throes of supermassive black holes in the near future. Data from these events is then able to be live-streamed to optimised supercomputing facilities in Australia to enable real-time detections. For more, see AAL’s news story here.
The GWDC currently supports research from six major Australian institutions – The Australian National University, Monash University, Swinburne University of Technology (host institution for the GWDC), The University of Melbourne, The University of Western Australia and The University of Adelaide. The GWDC operates alongside the existing Astronomy Data and Computing Services (ADACS) team at Swinburne, which has been providing a generalised data and computing service to the national astronomy community from early 2017.