PhD Studentship: Hidden black holes and the search for self-lensing binaries

We know of only 20 or so black holes in our galaxy yet predict there should be 10s of millions! Where are they hiding? It turns out that binary systems containing high mass stars (and so those which go on to produce black holes), evolve through a number of stages; in one such stage there is a black hole or neutron star orbiting at a large distance from a 'normal' companion star. This is a very long-lived state which accounts for the vast majority of the millions of binary systems harbouring neutron stars and black holes in our Galaxy. Self-lensing occurs when the binary system is viewed edge-on such that optical light from the companion star is bent towards us and magnified. In the case of microlensing this is a one-off event, whilst self-lensing repeats on the orbital period of the binary allowing it to be distinguished. New citizen science projects are being led by Prof Middleton's group (black-hole-hunters.org) which permit the vast amount of optical survey data taken by
instruments such as TESS to be studied, and self-lensing events searched for. The student will have an opportunity to explore these projects and the results coming from them, the latter involving the modelling and follow-up of any high probability events. The student will also explore the most promising methods for constraining the spin of the compact object being lensed which will involve both theoretical and computational modelling.
If you wish to discuss any details of the project informally, please contact:
Prof Middleton, Astronomy Research Group, Email: .

A very good undergraduate degree (at least a UK 2:1 honours degree, or its international equivalent).
Closing date: 31 August 2025.
Applications will be considered in the order that they are received, the position will be considered filled when a suitable candidate has been identified.