Bayesian inference of the Hubble constant

The discovery, just under a century ago, that the Universe is expanding introduced the idea of the Hubble constant, H0, which characterises both the current rate of the cosmological expansion and the overall timescale since the Big Bang.

In the last decade there have been several different methods which have yielded measurements of H0 to a precision of a few per cent; however, these measurements are in conflict with each other, a phenomenon known as the Hubble tension.

Resolving the Hubble tension is one of the main problems in cosmology at present, and a particular challenge comes from the (claimed) precision of the various measurements as it means great care must be taken with modelling assumptions, statistical methodology, and other technical aspects of the data analysis methods.

This project is centred around the use of Bayesian methods to provide a coherent approach to characterising the uncertainties in all these data-sets, with a particular focus on gravitational wave measurements of compact binary mergers (which will be independent of other current methods) and the tip of the red giant branch (TRGB) methods which have recently become competitive.

The project will involve a combination of data-wrangling, modelling and computational/numerical work with the aim of making the most robust statements possible just how fast the Unverise is actually expanding.