PhD Studentship: Understanding the Co-Evolution of Galaxies and Black Holes with PRIMA

Star formation and black hole growth are two of the most important processes in galaxy evolution. Although galaxies and their central black holes operate on very different physical scales, observations reveal a strong relationship between galaxy stellar mass and black hole mass in the present-day Universe. A key question is how this connection emerged: did galaxies and black holes grow together, or through alternating phases in which one process dominated the other?

The Probe far-infrared Mission for Astrophysics (PRIMA) will provide the first comprehensive census of both star formation and black hole growth during the peak epoch of galaxy evolution, 3-9 billion years after the Big Bang. Using far-infrared spectrophotometry, PRIMA will simultaneously measure star formation rates, black hole accretion, and galactic outflows, allowing us to determine how these processes are connected.

This is only possible in the mid- and far-infrared. Dust obscures the ultraviolet and optical light commonly used to trace star formation, while gas can block the X-rays used to identify black hole activity. PRIMA therefore offers a unique view of these hidden processes.

PRIMA is being proposed as NASA’s first $1 billion Probe-class astrophysics mission, with a planned launch in 2032. Prof. Seb Oliver is one of 27 co-investigators and leads the UK contribution. A key element of the mission will be the application of XID+, a world-leading modelling framework developed at Sussex, which can disentangle emission from multiple galaxies that appear blended together in observations.

The PhD project will focus on advancing XID+ to exploit the hyperspectral imaging and spectroscopy that PRIMA will provide. You will develop methodologies to separate blended galaxy emission, test them using state-of-the-art galaxy evolution simulations, and design your own PRIMA observational programmes.

The project will also make use of current world-leading facilities including JWST, Euclid, ALMA, Herschel, and SCUBA-2. By combining these with improved XID+ techniques, you will investigate the current limits of our understanding, demonstrate the power of new analysis methods, and help define priorities for future PRIMA observations.

The PhD programme will be shaped collaboratively with your supervisor and is expected to produce multiple refereed journal papers. It consists of three main sub-projects:

1. A New Determination of the Cosmic Star Formation History
   Apply hierarchical XID+ methods to JWST and Herschel survey data to derive far-infrared luminosity functions and measure the evolution of star formation across cosmic time.
2. Separating AGN and Star Formation in Blended Images
   Develop new XID+SED techniques that apply spectral energy distribution modelling directly to images rather than catalogues, enabling the separation of star formation and AGN contributions. The method will be tested on simulations and real survey data.
3. Hierarchical Measurement of AGN and Star Formation Histories
   Combine developments from the first two projects to determine both AGN activity and star formation directly from survey imaging data, bypassing traditional catalogue-based analyses.

The project is funded by the Science and Technology Facilities Council (STFC), providing access to all UKRI postgraduate researcher benefits.

For more information on this project, please contact Prof. Seb Oliver.

To apply for this role please click on the 'Apply' button above.

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