On model independent cosmic determinations of $H_0$
Year: 2021
Type: preprint
Abstract: Motivated by Hubble tension, we have recently witnessed a number of $H_0$ determinations at cosmological scales. Here we compare two techniques, Taylor expansion and Gaussian Processes (GP). While Taylor expansion is truly model independent in a limited range, we show that one can reduce the $H_0$ errors by increasing the range of the expansion, but the approximation suffers. For GP, we confirm for the Mat\'ern class kernels that the errors on $H_0$ decrease as the parameter $\nu \rightarrow \infty$, where we recover the Gaussian kernel. The errors from GP are typically smaller than Taylor and by mapping the GP analysis back into the Taylor expansion, we show that GP explores a smaller portion of the parameter space. In a direct comparison of GP with the CPL model, the simplest model of dynamical dark energy, we see that correlations are suppressed by GP relative to CPL. Therefore, GP cannot be model independent. We emphasise that if a truly model independent statement of Hubble tension exists, then it will have serious consequences for the FLRW framework.
Source: arXiv (Cornell University)
Authors: Eoin Ó Colgáin, M. M. Sheikh-Jabbari
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W3121692052