26th Australian Institute of Physics Congress and the Australian and New Zealand Conference on Optics and Photonics

The Lucky Country: The science case for an Australian gravitational wave detector

Not scheduled

20m

Belinda Hutchinson Building (The University of Sydney )

Contributed Oral AIP | Astronomy (ASTRO)

Description

Since the first detection of gravitational wave (GW) emission from coalescences between black holes and neutron stars, we have only observed one confirmed multi-messenger detection: GW170817. This single event showed the promise GWs and multi-messenger astrophysics have to reveal new information about the physics of matter at densities unachievable in terrestrial laboratories. GW170817 also showed that GWs offer new opportunities to resolve the Hubble tension, an outstanding problem in cosmology in which different methods of measuring the expansion rate of the Universe cannot be reconciled. Every decision we make about the design and location of gravitational wave detectors constructed over the next decade must prioritise capturing more events like GW170817 if we are to realise the potential of GWs as a messenger.

Two factors limit the discovery potential of a detector network: sensitivity and sky localisation. Detector sensitivity is primarily dictated by the experimental equipment and governs how far into the Universe our detector can observe. Sky localisation, the ability to pinpoint GW sources on the sky, is most affected by the number of non-redundant inter-detector baselines in a global GW detector network.

We discuss the development of a series of figures of merit motivated by multi-messenger astrophysics. These that allow detector designs and global network configurations to be benchmarked in cost-benefit analyses. We will show that maximising the scientific potential of gravitational waves as a messenger requires a detector in Australia, and discuss the current efforts underway to make an Australian detector a reality. In particular, we demonstrate how a detector network consisting of a Cosmic Explorer design detector in the US, Einstein Telescope in Europe, and a detector with comparable sensitivity to the LIGO O5 detectors in Australia can enable groundbreaking insights into cosmology - measuring the Hubble constant to <10% - and the physics of extreme matter.