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Radio contours overlaid on X-ray emission from the radio galaxy 3C 432 at z=1.785 when the Universe was just 4 billion years old (Erlund et al. 2006). X-ray emission is seen from the radio lobes thought to be due to up-scattering of the CMB.

Radio contours overlaid on X-ray emission from the radio galaxy 3C 432 at z=1.785 when the Universe was just 4 billion years old (Erlund et al. 2006). X-ray emission is seen from the radio lobes thought to be due to up-scattering of the CMB.

Supermassive black holes at the centres of galaxies produce powerful relativistic jets of electrons which can be observed at radio wavelengths across cosmic time due to their high luminosity. Current studies have not found luminous radio sources earlier than 1.6 billion years after the Big Bang although there is evidence for fully formed super-massive black holes at 1.2 billion years after the Big Bang. Where are all the radio sources in the early Universe?
A current popular theory is that the relativistic electrons interact with the Cosmic Microwave Background (CMB) and lose energy (thus suppressing radio emission). The energy is not lost though with the CMB photons being up-scattered to very high energies, typically in the X-ray regime but possibly lower frequencies too.
This project will investigate this effect by modelling it on current known high redshift radio galaxies and making predictions about how to best detect the up-scattered photons. The student will then use the wide range of observational facilities available to Australian astronomers to observe this emission. The model will be further tested on large area radio surveys such with the Murchison Widefield Array and the Australian Square Kilometre Array Pathfinder and with the next generation all-sky X-ray survey with eROSITA. This project may also include predictions on the up-scattering of CMB photons for the very first super-massive black holes.

Co-Supervisor

Dr Guillaume Drouart

Research Associate

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