Observational Constraints and Cosmic Growth Index of Realistic f(G) Gravity Frameworks using MCMC Analysis
Abstract
We present a comprehensive observational analysis of modified Gauss--Bonnet, or f(G), gravity by investigating both the background cosmological expansion and sub-horizon linear matter perturbations. We consider two viable functional forms: an arctangent parameterization (Model~I) and a generalized polynomial power-law model (Model~II). Using a Markov Chain Monte Carlo (MCMC) ensemble sampler, we constrain their parameter spaces through background and structure-growth observations. Our analysis employs cumulative combinations of Cosmic Chronometers (CC), the Pantheon+ Type Ia Supernovae compilation (PP), Redshift-Space Distortions (RSD), and the Year-1 Baryon Acoustic Oscillation measurements from the Dark Energy Spectroscopic Instrument (DESI BAO). The inclusion of DESI BAO data produces a noticeable downward shift in the preferred values of the Hubble constant, H0, and present matter density parameter, Ωm0. For Model~II, the full analysis yields H0=64.02+4.13*−3.08,km,s−1,Mpc−1 and Ω*m0=0.249+0.047−0.038. We further assess the statistical performance of the models relative to ΛCDM using ΔAICc, ΔBIC, and ΔDIC. For Model~II, the full dataset gives ΔAICc=4.233 and ΔDIC=5.971, favoring the ΛCDM baseline. At the perturbation level, both models exhibit stable growth histories compatible with large-scale structure observations. The models predict transitions in the late-time expansion dynamics at z≈0.5005 and z≈0.6086 for Models~I and II, respectively, highlighting differences in their cosmological evolution.
Related
- Cosmic Expansion in f(Q,C) Gravity: Observational Constraints and Geometric Diagnostics
- Constraints on Rastall gravity from current observational data
- Observational constraints on a non-minimally coupled scalar field in non-metricity gravity with an extra degree of freedom
- Observational constraints on Diffusion Cosmologies in Unimodular Gravity from DESI DR2
- Modified Gravity Framework for the Woods-Saxon Inflation: Theoretical Foundations and Observational Constraints
BibTeX
@misc{dhankar2026observational,
title = {{Observational Constraints and Cosmic Growth Index of Realistic $f(G)$ Gravity Frameworks using MCMC Analysis}},
author = {Praveen Kumar Dhankar and Munyeshyaka Albert and Mohit Thakre and Joseph Ntahompagaze and Safiqul Islam and Farook Rahaman},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.16037},
eprint = {2609.16037},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.16037},
note = {CC BY-NC-SA 4.0},
}
RIS
TY - UNPB
TI - Observational Constraints and Cosmic Growth Index of Realistic f(G) Gravity Frameworks using MCMC Analysis
AU - Praveen Kumar Dhankar
AU - Munyeshyaka Albert
AU - Mohit Thakre
AU - Joseph Ntahompagaze
AU - Safiqul Islam
AU - Farook Rahaman
PY - 2026
DA - 2026/09/11
PB - arXiv
DO - 10.48550/arxiv.2609.16037
UR - https://arxiv.org/abs/2609.16037
AB - We present a comprehensive observational analysis of modified Gauss--Bonnet, or f(G), gravity by investigating both the background cosmological expansion and sub-horizon linear matter perturbations. We consider two viable functional forms: an arctangent parameterization (Model~I) and a generalized polynomial power-law model (Model~II). Using a Markov Chain Monte Carlo (MCMC) ensemble sampler, we constrain their parameter spaces through background and structure-growth observations. Our analysis employs cumulative combinations of Cosmic Chronometers (CC), the Pantheon+ Type Ia Supernovae compilation (PP), Redshift-Space Distortions (RSD), and the Year-1 Baryon Acoustic Oscillation measurements from the Dark Energy Spectroscopic Instrument (DESI BAO). The inclusion of DESI BAO data produces a noticeable downward shift in the preferred values of the Hubble constant, H_0, and present matter density parameter, Ω_m0. For Model~II, the full analysis yields H_0=64.02^+4.13*−3.08,km,s^−1,Mpc^−1 and Ω*m0=0.249^+0.047_−0.038. We further assess the statistical performance of the models relative to ΛCDM using ΔAIC_c, ΔBIC, and ΔDIC. For Model~II, the full dataset gives ΔAIC_c=4.233 and ΔDIC=5.971, favoring the ΛCDM baseline. At the perturbation level, both models exhibit stable growth histories compatible with large-scale structure observations. The models predict transitions in the late-time expansion dynamics at z≈0.5005 and z≈0.6086 for Models~I and II, respectively, highlighting differences in their cosmological evolution.
ER -