Towards Velocity Field Reconstructions with BORG
Date:
Accurate peculiar velocity field maps are critical for various cosmological analyses, including Hubble constant determinations and density field reconstructions. In this talk, I will discuss the challenges faced when reconstructing the peculiar velocity field from distance tracers, as well as the collective efforts of the Aquila Consortium in developing a physical, Bayesian hierarchical model for this task. We employ Bayesian hierarchical models, connecting the initial matter density with peculiar velocity data to reconstruct the final density and velocity fields. Utilising the BORG algorithm, this approach outperforms traditional methods, even in the face of model mis-specification. I will discuss the importance of the inhomogeneous Malmquist bias for obtaining an unbiased velocity field reconstructions and will present results from simulations and peculiar velocity datasets demonstrating our model’s accuracy. In the latter part of the presentation, I will introduce a novel unified pipeline, which facilitates cosmological parameter sampling. This integration allows for the inclusion of peculiar velocity data in initial condition reconstructions which produce accurate and self-consistent density and velocity fields. This advancement holds significant implications for cosmology and astrophysics and could provide valuable insights into the S8 tension.
- Given at:
- Euclid Additional GC Probes Telecon (Nov. 2023)