Growth factor in teleparallel Gauss-Bonnet gravity

Abstract

Teleparallel gravity offers a competing geometric framework on which to build cosmological models. The Gauss-Bonnet invariant captures key aspects of the underlying geometry that has been shown to be an interesting way to form cosmological models beyond $Λ$CDM cosmology. In this work, we explore three competing cosmological models in $F(T,T_G)$ cosmology in the context of their evolution of the growth of structure in the Universe. This is a core test of the viability of any cosmological model. In our work, we show how these models are qualitatively competitive with $Λ$CDM cosmology for certain ranges of model parameters. Interestingly, the models can arrive at the same level of growth as $Λ$CDM while producing possible deviations at intermediate scales.

Figures (3)

• Figure 1: Growth factor evolution for model A. The bold line represents the growth factor for $\Lambda CDM$. The dotted-dashed, dashed, and thick dashed lines represent the growth factor for model A at parameter values $p_1=0.001$, $p_1=0.01$, and $p_1=0.0003$, respectively. We see that the model deviates from $\Lambda CDM$ for all values of $p_1$.
• Figure 2: Growth factor evolution for model B. The solid curve corresponds to the $\Lambda$CDM growth factor, while the dashed-dotted curve denotes the growth factor for model B evaluated at $c_{22}=1.7$. The results indicate that the model closely tracks $\Lambda$CDM.
• Figure 3: Growth factor evolution for model C. The solid curve represents the $\Lambda$CDM growth factor, while the dashed-dotted curve corresponds to the growth factor for model C evaluated at $p_3=0.05$. The results show that the model exhibits only minimal deviations from the $\Lambda$CDM prediction.