Joint Astrophysical Colloquium
Cosmological reconstruction: BAO and the cosmic web
Ravi Sheth (University of Pennsylvania)
Tuesday 07/10/2025 @ 14:00, Sala Antonio Sollima (IV piano Battiferro)
The Baryon Acoustic Oscillation signal provides a rather robust ruler for cosmological constraints. The ruler must be 'standardized' and the process of doing so is known as 'reconstruction'. I'll describe two methods: one, called the Linear Point, reconstructs the statistical ruler directly, and the other reconstructs the entire fluctuation field in which the ruler is measured. The second uses Optimal Transport, a framework for addressing a large range of problems in machine learning, statistics and physics. I'll contrast OT with the more standard approach, highlighting how it provides a natural extension that potentially provides accuracy to smaller scales. I'll also outline other places in which OT might provide a useful framework: delensing of the CMB and studies of strongly lensed systems which constrain the Hubble constant from measurement of time-delays between images.