The afterlife of black-hole jets: modelling remnant radio bubbles and AGN feedback

About the research project

Jets launched by supermassive black holes inflate enormous bubbles of relativistic plasma within the hot atmospheres surrounding galaxies and galaxy clusters. When the jets switch off, these bubbles rise, deform and mix with the surrounding gas, transporting energy far from the central black hole. Capturing this evolution is important for understanding active galactic nucleus (AGN) feedback, but resolving the associated fluid dynamics with hydrodynamic simulations is computationally expensive, particularly when exploring large parameter spaces or repeated episodes of jet activity.

This PhD project will develop a computationally efficient mathematical framework for modelling the evolution of black-hole jet bubbles after their jets switch off. The RAiSE (Radio AGN in Semi-analytic Environments) model, developed at the University of Tasmania, will provide the physical conditions at the end of the active jet phase, forming the initial conditions for a new model of the subsequent remnant evolution. Spectral methods will be used to model the interaction between the low-density remnant radio bubble and its surrounding atmosphere, allowing the accuracy and computational cost of the solution to be balanced. The project will investigate how buoyancy and fluid instabilities drive the deformation and mixing of the bubble with the ambient medium, and characterise regions of parameter space associated with rapid change or long-term stability. This will replace the existing assumption that a coherent bubble simply begins to rise after jet switch-off with a mathematical description of how energy is transported and dissipated during the remnant phase.

The framework will be applied across a broad parameter space of jet powers, lifetimes and environments, and extended to consider repeated AGN outbursts analytically. This will make it possible to determine how successive generations of bubbles interact with an atmosphere modified by previous activity and how repeated outbursts redistribute energy over multiple cycles of AGN activity. Working with collaborators specialising in cosmological simulations of galaxy formation, the resulting models will be used to develop efficient, physically motivated prescriptions for unresolved AGN heating and energy transport. The framework may also be coupled to radio-emission models to make observational predictions for remnant sources, providing an independent test of the underlying physics.

Primary supervisor

Meet Doctor Ross Turner

Funding

Applicants will be considered for a Research Training Program (RTP) scholarship or Tasmania Graduate Research Scholarship (TGRS) which, if successful, provides:

• a living allowance stipend funded by University of Tasmania of $34,315 per annum for 3.5 years
• a relocation allowance of up to $2,000
• a tuition fees offset covering the cost of tuition fees for up to four years (domestic applicants only)

A tuition fee offset may be offered to eligible international applicants following competitive assessment 

As part of the application process you may indicate if you do not wish to be considered for scholarship funding.

Other funding opportunities and fees

For further information regarding other scholarships on offer, and the various fees for undertaking a research degree, please visit our Scholarships and fees on research degrees page.

Eligibility

Applicants should review the Higher Degree by Research minimum entry requirements.

Ensure your eligibility for the scholarship round by referring to our Key Dates.

Additional eligibility criteria specific to this project/scholarship:

• Applications are open to applicants with an Honours or Masters degree in physics, applied mathematics or a closely related area.

Selection criteria

The project is competitively assessed and awarded. Selection is based on academic merit and suitability to the project as determined by the College.

Additional essential selection criteria specific to this project:

• Honours or Masters degree in physics, applied mathematics, or a closely related area.
• Capacity for critical thinking and quantitative problem solving.
• Ability to work both independently and as part of a team.

Additional desirable selection criteria specific to this project:

• Experience in any of: Python or C coding, dynamical systems, fluid dynamics, theoretical astrophysics.

Application process

1. Select your project, and check that you meet the eligibility and selection criteria, including citizenship;
2. Contact Doctor Ross Turner to discuss your suitability and the project's requirements; and
3. In your application:
   • Copy and paste the title of the project from this advertisement into your application. If you don’t correctly do this your application may be rejected.
   • Submit a signed supervisory support form, a CV including contact details of 2 referees and your project research proposal.
4. Apply prior to 1 October 2026.

Full details of the application process can be found under the ' How to apply ' section of the Research Degrees website.

Following the closing date applications will be assessed within the College. Applicants should expect to receive notification of the outcome by email by the advertised outcome date.

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