Constraining f(R) models with cosmic chronometers and the HII galaxy Hubble diagram

TL;DR

This paper constrains f(R) gravity models using cosmic chronometers and HII galaxy data, deriving analytical expressions for H(z) and d_L(z), and performs a combined observational analysis to test model viability.

Contribution

It provides analytical approximations for f(R) models' Hubble rate and luminosity distance, and applies a combined observational approach with Gaussian Processes for model constraints.

Findings

Constraints on deviation parameter b and cosmological parameters _m and h.

Analytical expressions for H(z) and d_L(z) in f(R) models.

Joint analysis improves model parameter constraints.

Abstract

We consider several well-known f(R) cosmological models and constrain their parameters, namely the deviation parameter b and the cosmological parameters \Omega_m and h. We first obtain analytical approximations for the Hubble rate H(z) and the luminosity distance d_L(z) in terms of these parameters, and then test these against the observational expansion rate derived from cosmic chronometers and the distance modulus in the HII galaxy Hubble diagram, obtained in a model-independent way using Gaussian Processes (GP). We first optimize the models based solely on the cosmic chronometers and then repeat this process with a joint analysis using both the cosmic chronometers and HII galaxies.