PhD in physics (M/F) – Measurement of the Hubble constant with gravitational waves

The detection of gravitational waves produced during the merger of compact objects such as black holes or neutron stars allows us to study the universe with a completely new kind of probe. In particular, it becomes possible to measure cosmological parameters independently of electromagnetic observations. Currently, estimates of the Hubble constant H0 obtained from light emitted by nearby objects (Cepheids, Type Ia supernovae) or distant objects (cosmic microwave background) are only marginally compatible, with a discrepancy around 4–5 sigma. Measuring H0 with gravitational waves could help understand the origin of this disagreement. The PhD work will involve refining this measurement using new data from the LIGO-Virgo-KAGRA (LVK) interferometers, particularly by leveraging galaxy catalogs to make the best use of the available information. The project will include mastering data analysis, improving existing codes (in Python), and developing analyses for the upcoming gravitational wave catalog from the O4b and O4c runs. The thesis will also address studying systematic effects related to the modeling choices used in the analysis. The person will be a full member of the LVK collaboration and will have access to the computing resources necessary to carry out the analyses.