Application deadline: Wednesday, January 06, 2027
Funding: Self-Funded PhD Students Only
About the Project
Supervisors: Professor Poshak Gandhi
Does the Universe look the same in every direction? Distant quasars, powered by giant black holes, hint that it might not. Using public telescope surveys, this project will investigate whether that surprising signal reveals a problem with our understanding of the Universe or arises from how we observe the sky.
Is the Universe statistically isotropic on the largest scales? This assumption underpins our standard cosmological model, yet observations of distant quasars have revealed a possible challenge. Their sky distribution shows a dipole whose amplitude and direction may differ from expectations based on our motion relative to the cosmic microwave background. Whether this reflects new physics, cosmic structure or observational biases remains unresolved.
In this project, you will use supermassive black holes as beacons to test this assumption. You will analyse public WISE and Gaia quasar catalogues, supported by public spectroscopy and complementary SPHEREx and Euclid releases where available. Infrared spectra will help establish how quasar colours and spectral shapes influence the expected signal, while high resolution imaging will help identify blended sources and contaminants.
Key goals include:
- measuring dipole amplitudes and directions for quasar samples selected by brightness, colour and redshift
- modelling how Galactic dust, survey sensitivity, source confusion and incomplete sky coverage affect these measurements
- developing simulations and Bayesian methods that distinguish observer motion, cosmic clustering and additional anisotropy
- testing whether consistent results emerge across surveys while accounting for shared data and selection effects
The project combines observational astrophysics, cosmology and data science. You will develop analysis tools and publish constraints on cosmic isotropy, with valuable outcomes whether the anomaly persists or is explained by survey effects. Training will cover scientific computing, statistical inference, survey analysis and scientific communication. You will need to be comfortable with scientific computing in any language of your choice.
Entry requirements
A UK 2:1 honours degree, or its international equivalent.
You should be comfortable with scientific computing in any language of your choice.
Fees and funding
We offer a range of funding opportunities for both UK and international students. Horizon Europe fee waivers automatically cover the difference between overseas and UK fees for qualifying students.
Competition-based Presidential Bursaries from the University cover the difference between overseas and UK fees for top-ranked applicants.
Competition-based studentships offered by our schools typically cover UK-level tuition fees and a stipend for living costs for top-ranked applicants.
Funding will be awarded on a rolling basis, so apply early for the best opportunity to be considered.
For more information, please visit our postgraduate research funding pages.
How to apply
You need to:
- choose programme type (Research), 2027/28, Faculty of Engineering and Physical Sciences
- select Full time or Part time
- search for programme PhD Physics (7089)
- add name of the supervisor in section 2 of the application
Applications should include:
- your CV (resumé)
- 2 academic references
- degree transcripts and certificates to date
- English language qualification (if applicable)
Contact us
Faculty of Engineering and Physical Sciences
For questions about applying, doctoralcollege-admissions@soton.ac.uk.
Project leader
For an initial conversation, poshak.gandhi@soton.ac.uk.
The School of Physics and Astronomy is committed to promoting equality, diversity inclusivity as demonstrated by our Athena SWAN award. We welcome all applicants regardless of their gender, ethnicity, disability, sexual orientation or age, and will give full consideration to applicants seeking flexible working patterns and those who have taken a career break. The University has a generous maternity policy, onsite childcare facilities, and offers a range of benefits to help ensure employees’ well-being and work-life balance. The University of Southampton is committed to sustainability and has been awarded the Platinum EcoAward.