A f(z)CDM approach for determining the Hubble constant

• Grant number: 22/14565-9
• Support Opportunities: Scholarships abroad - Research Internship - Master's degree
• Start date: January 30, 2023
• End date: July 29, 2023
• Field of knowledge: Physical Sciences and Mathematics - Physics
• Principal Investigator: Edivaldo Moura Santos
• Grantee: Alexandra Turmina Petreca
• Supervisor: Micol Benetti
• Host Institution: Instituto de Física (IF). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Institution abroad: Scuola Superiore Meridionale (SSM), Italy
• Associated to the scholarship: 21/13752-7 - A Bayesian method for determination of the Hubble constant, BP.MS

Abstract

With the advent of precision cosmology some tensions were detected in the cosmological parameters, between them, the one on the value of the current rate of the expansion of the universe. Motivated by such a tension on the Hubble parameter, we propose to investigate the Hubble constant value using a cosmographic approach, inferring from the data possible features that the cosmological model should take into account. The model to be used in this study is called f(z)CDM, in which the f(z) function is a cosmographic series used to describe the evolution of the recent universe. To build the f(z), a Padè approximation was chosen, that have shown a better convergence at high redshifts than the standard Taylor series expansion of the luminosity distance. In this model, cosmography and standard cosmological model are combined, considering a cosmographic approximation up to an appropriate redshift and from it a evolution of standard type. The theoretical predictions will be performed with the Boltzmann solver code CAMB and posterior distributions of cosmological and cosmographic parameters obtained with the help of the CosmoMC package, a Monte Carlo Markov Chains algorithm. The dataset to be used is composed of measurements of the temperature of the cosmic microwave background and measurements of type Ia supernovae.