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Science

This page summarises the key science aims of the QUOCKA survey project.

Key science aims

What is the intrinsic magnetoionic structure of radio galaxies and its evolution?

Linearly polarized synchrotron radiation is a sensitive tracer of magnetic fields in distant radio galaxies. That same radio emission is also a delicate probe of gas that is both ionised and magnetised, and either co-located with the emitting regions or found in the regions traversed in the direction of our radio telescopes. Details of polarized radiation as a function of radio frequency encode the properties and distribution of the gas and magnetic fields. One of the primary aims of the QUOCKA survey is to combine the wide ATCA bandwidth with detailed models of the emission and propagation of polarized radio emission. With these resources we will reveal the structure of radio galaxies on multiple scales and link those properties to the evolution of the galaxies themselves.

The picture developed by QUOCKA will also help us to interpret observations of radio galaxies detected with ASKAP’s POSSUM survey. ASKAP is soon to be the most efficient instrument in the world for detecting polarized radio galaxies, but provides limited bandwidth. ASKAP and ATCA are highly complementary for detecting and understanding magnetism in the cosmos.

A broadband circular polarisation survey

Radio galaxies also emit circular polarization, which is a powerful tracer of jet magnetic fields. To date, circular polarization has not been comprehensively studied. The ATCA provides exquisite polarization data, which is needed for new progress. QUOCKA will provide unique information about how many radio galaxies produce circular polarization. We will gain new understanding by establishing how often circular polarization is found in different source types. We will also model the radiation to understand the emission mechanism. Results from the QUOCKA survey will motivate detailed followup with the Square Kilometre Array.