This talk was part of the UH Centre for Astrophysics Research (CAR) 2023-2024 seminar series. For the ongoing programme, please see: https://www.herts.ac.uk/research/cent...

Date: 1 Nov 2023
Speaker: Prof Alan Heavens – Imperial College London
Title: Perfect Cosmology with Imperfect Data

Abstract: Light paths from distant galaxies are distorted by passage through the clumpy Universe, meaning that we do not see those galaxies as they really are, or rather, were. Those imperfections, known as Cosmic Shear, contain information about the matter distribution and the properties of Dark Energy, as well as being able to probe whether Einstein gravity is correct. Extracting this information is challenging and every ounce has to be extracted to distinguish between different scenarios. I will review the field and discuss Bayesian ways to use the data without losing information. As an illustration of one such technique, Simulation Based Inference (AKA Likelihood-free inference), which is applicable to many areas of science, I’ll also show how Pantheon+ Supernova Cosmology can be done just as well with 3 numbers (1304.68, 23857.17, −1341.94), as with the 1590 fluxes from the original sample.