From MSc to postdoctoral researcher: Pritha Paul awarded PhD in theoretical cosmology
Dr Pritha Paul was awarded her PhD by Queen Mary’s School of Physical and Chemical Sciences in February 2026, after joining the school as a student on the MSc Astrophysics programme.
Pritha now holds a postdoctoral position before taking up a further postdoc at Ludwig-Maximilians-Universität Munich later this year. It is one of Europe's leading centres for cosmological research, with close ties to the Max Planck Institute for Astrophysics and the European Southern Observatory headquarters.
Pritha's doctoral research, supervised by Professor Chris Clarkson, focused on the theoretical modelling of relativistic effects in the large-scale distribution of galaxies. As survey programmes such as DESI, Euclid and the Square Kilometre Array push into new regimes of scale and precision, the standard Newtonian approximations used to model galaxy clustering become inadequate, and a proper general relativistic treatment is required both to extract unbiased cosmological constraints and to test gravity on the largest observable scales. Her work developed the analytical framework needed to handle these corrections consistently across a range of statistics, including the power spectrum and higher-order correlation functions.
The most prominent result of her doctorate was a paper published in Physical Review Letters in September 2024, co-authored with Chris Clarkson and Roy Maartens of the University of the Western Cape. Recent measurements of the galaxy four-point function had found an apparent parity asymmetry in the large-scale distribution of galaxies. It is a result that, if of primordial origin, would require fundamental modifications to the standard cosmological model and most models of inflation. Pritha and her co-authors demonstrated that relativistic effects already present within standard observational cosmology generate parity-violating contributions at the level of the bispectrum and trispectrum, and that these must be accounted for in any serious analysis of the observations. The paper was selected as an Editors' Suggestion by Physical Review Letters (PRL). Publishing a first-author paper in PRL during a PhD is a notable achievement by any standard.
Her broader publication record spans wide-angle corrections to multi-tracer power spectra, the detection significance of relativistic signals in next-generation surveys, and, in work completed after her thesis, visualisations of how relativistic redshift-space distortions deform large-scale structures beyond the standard ellipsoidal approximation.
"The MSc gave me both the technical foundation and the research environment to make the transition into a PhD in cosmology, even though I started from a mathematics degree,” said Dr Paul. "Working within the Cosmology Group here has been a fantastic experience, and I'm excited to continue this line of research in Munich."
Pritha's trajectory, from MSc entry to an international postdoctoral appointment via a first-author PRL, illustrates what Queen Mary’s MSc Astrophysics is designed to make possible for students with the ability and ambition to pursue research careers.