4 minute read
The software developers catching gravitational waves
from Contact 14
BY SEBASTIAN NEUWEILER (SKAO)
As several SKA pathfinder telescopes detected the strongest evidence yet for low-frequency gravitational waves (see Let's talk about piece in this edition of Contact), in the inner east of Melbourne, Australia, a software company also had reason to celebrate.
Fourier Space company is behind pulsar timing array software and instrumentation used by radio astronomy observatories globally, including Parkes’ multibeam pulsar signal processor and MeerKAT’s pulsar timing processor.
Born from a desire to enable astronomy and space entities to solve their signal acquisition and processing challenges rapidly and effectively, Fourier Space CEO and co-founder Andrew Jameson said the skills and software libraries of the team had been honed over decades of instrumentation development for radio astronomy.
“Not only do we want to work on the technical aspect, but we also care deeply on the scientific outcome, with everyone in the company having a very strong background in pulsar astronomy,” he said.
“A lot of the data that was recorded and collected as evidence of low-frequency gravitational waves was done with software our team had designed and contributed to. There’s a great sense of collective accomplishment, that you’re part of the engineering right up to discovery in science.
“That’s exactly what we want to do in our involvement in the SKA endeavour: be able to build over the next several years the instrumentation that will lead to the next generation of breakthroughs and cutting-edge science.”
The team has also designed the SKAO’s pulsar timing processor, which will be deployed at the Australian and South African sites to observe multiple pulsars in parallel. This will be accomplished by processing multiple phased-array beams, each pointing to a different spot on the sky, from the correlator beamformer of the central signal processor.
Fourier Space co-founder Willem van Straten, who led the pulsar timing pre-construction team for the SKA telescopes, said the team’s approach utilised “coherent de-dispersion” to completely correct the dispersive effects of the interstellar medium.
“The usual way we think of dispersion is through a rainbow, different wavelengths travelling at different speeds when they’re not travelling through a vacuum,” he said. “It’s what causes red and purple to refract at different angles when they go through glass and radio waves to travel at different speeds through the interstellar medium. De-dispersion allows you to fully correct that in a way that other techniques can’t, as it reveals the high time resolution in the pulsar signal. It’s that high time resolution structure that allows you to achieve the highest timing precision.”
The pulsar processors designed by Fourier Space will be capable of coherently de-dispersing over 1 GHz of bandwidth in real time for timing and searching applications. Jameson said this would allow the SKA telescopes to have significantly more instantaneous bandwidth and observational power than other instruments.
“The software scales on that computing power, but there’s a lot of things that enable that right through the whole design of the telescopes,” he said.
“From the receivers, which sample a large bandwidth, to the stages of signal processing that occur which accommodate those large bandwidths, to then forming multiple beams and looking at different pulsars simultaneously to increase your efficiency.
“The SKA telescopes are really going to represent a big step forward in gravitational wave astronomy, particularly with the number of pulsars that they will observe.”
