Forward modelling of peculiar velocities and large-scale structure

by Richard Stiskalek (Oxford University)

Thursday Nov 20, 2025, 3:00 PM → 4:00 PM Europe/Paris

Salle des séminaires (IAP)

I will present recent advances in Bayesian forward modelling of peculiar-velocity samples (Tully–Fisher, Fundamental Plane, and Type Ia supernovae) to reassess what they reveal about the local Universe. I will first discuss linear-theory modelling based on galaxy clustering and show what it implies, when combined with peculiar-velocity data, for f sigma8 and S8, finding good agreement with LCDM across independent probes. I will then revisit claims of anisotropy in the local expansion rate, showing that, despite apparent evidence for it, the overall bulk flow remains consistent with LCDM, contradicting results claiming an increasing bulk flow. Finally, I will highlight new forward-modelling results from the BORG framework and the Manticore-Local suite, which provide a state-of-the-art velocity-field model of the local Universe and enable a supernova-free measurement of the Hubble constant using only 35 Cepheid-host galaxies.