Under the direction of Theme leader Professor Tamara Davis, OzGrav’s Physics Theme will use gravitational waves and transient cosmological signals as a tool for exploring many realms of fundamental physics with high precision. We will explore the nature of spacetime by using gravitational wave observations to probe gravity in the ultra-strong-field regime near the event horizons of black holes. We will probe the nature of neutron stars, exploring the behaviour of matter at densities comparable to those in the atomic nucleus, and connect astronomy to physics in ways inaccessible by any Earth-based laboratories. We will reveal the nature of the Universe itself, using merging binaries and fast radio bursts to measure the age, mass, expansion rate, and composition of the Universe.
Key Programs
GRAVITY
Chairs: Prof Paul Lasky (Monash) & Ling (Lilli) Sun (ANU)
The goal of this project is to perform stringent tests of fundamental physics using both the strongest gravitational fields in the universe and relativistic binary radio pulsars. Advances in LIGO technology have meant we are now routinely witnessing the merging of stellar-mass black holes, where the gravitational field at their horizons is ten billion times stronger than in the solar system. Our team’s expertise in general relativity, Bayesian inference, and signal processing are allowing us to test Einstein’s theory in these ultra-strong-field regimes. We are measuring strong-field effects predicted by Einstein’s relativity and providing robust constraints on physics. We are gaining insights from the exquisitely precise timing measurements of relativistic binary pulsars using the MeerKAT, Parkes and ultimately SKA telescopes.
EXTREME MATTER
Chairs: Prof Andrew Melatos (Uni Melb) & Prof Ryan Shannon (Swinburne)
The goal of this project is to measure the properties of bulk matter at nuclear density. Neutron stars harbour the densest bulk matter and most intense electromagnetic fields in the Universe. Observing gravitational and electromagnetic radiation from neutron stars is the only way to study these extreme physical conditions. Studies of this kind probe a rich variety of fundamental physics, including the residual strong force between nucleons, which governs the equation of state of bulk nuclear matter, and phenomena such as nuclear superfluidity and superconductivity. Related astrophysics of fundamental interest includes the masses, spins, and moments of inertia of relativistic stars, and the structure and evolution of their magnetic fields.
COSMOS
Chairs: Prof Chris Blake (Swinburne) & Prof Ilya Mandel (Monash)
The goals of this project are to determine fundamental cosmological parameters, map the cosmic evolution of the Universe, and explore the astrophysics of massive binary stars. Gravitational waves provide a powerful new tool for mapping the cosmological properties of the Universe and the extreme events that produce them. We will use GW sources as standard sirens to produce an accurate measurement of the cosmic expansion rate, helping to unravel a key unsolved mystery in cosmology. The population of compact binary mergers these GW reveal will transform our understanding of the evolution of massive stars, their binary interactions and star cluster dynamics. Meanwhile we will make use of the dramatically increased sample of localised fast radio bursts over the Centre lifetime to develop a second and completely independent cosmological probe, one that can measure both the average properties of the baryonic content of the Universe and trace the structure of the cosmic web.